multiple launch rocket system

MM4806

MULTIPLE LAUNCH ROCKET SYSTEMAND DEEP ATTACK MISSILE SYSTEM

Subcourse Number MM4806

EDITION A

Missile and MunitionsUnited States Army Combined Arms Support Command

Fort Lee, Virginia 23801-1809

7 Credit Hours

Edition Date: October 1990

SUBCOURSE OVERVIEW

The Multiple Launch Rocket System (MLRS) is a free-flight rocket system that provides a high-volume fire supplement to tube artillery. The Deep Attack Missile System uses most of the same equipment as the MLRS, but substitutes Army Tactical Missile System (ATACMS) missiles for the MLRS rockets to achieve increased range and accuracy against the deep threat. Both systems have sophisticated hydraulic, mechanical, electrical, and electronics subsystems that must be maintained in order to keep them in operation on the battlefield. As a missile maintenance supervisor, MOS 27B40, you may have to supervise maintenance on the MLRS or the Deep Attack Missile System.

This seven-lesson subcourse has been developed for those who are new to the MLRS and the Deep Attack Missile System and for those who desire a refresher. Lesson 1 describes the general characteristics of the MLRS, its major components, and its communications net. Lesson 2 covers the fire control system menus; the hydraulic, mechanical, and electrical assemblies of the launcher loader module (LLM); and other MLRS components. Lesson 3 provides preventive maintenance checks and services for the system. Lesson 4 presents troubleshooting and repair background and procedures for the LLM. Lesson 5 presents troubleshooting and repair background and procedures for the fire control system (FCS). Lesson 6 identifies the major components of the MLRS carrier and describes maintenance. Lesson 7 identifies the major components, supporting equipment, and testing of the Deep Attack Missile System.

There are no prerequisites for this subcourse.

This subcourse reflects the doctrine that was current at the time the subcourse was prepared. In your own work situation, always refer to the latest publications.

The words “he,” “him,” “his,” and “men,” when used in this publication, represent both the masculine and feminine genders unless otherwise stated.

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TERMINAL LEARNING OBJECTIVE

Task: You will learn how to supervise maintenance on the MLRS and the Deep Attack Missile System.

Conditions: You will have this subcourse book and will work without supervision.

Standards: You must make a passing score of 70% on the end-of-subcourse examination to receive credit for this subcourse.

*** IMPORTANT NOTICE ***

THE PASSING SCORE FOR ALL ACCP MATERIAL IS NOW 70%.

PLEASE DISREGARD ALL REFERENCES TO THE 75% REQUIREMENT.

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TABLE OF CONTENTS

SUBCOURSE OVERVIEW, i

TERMINAL LEARNING OBJECTIVE, ii

LESSON 1: TACTICAL USE, MAJOR COMPONENTS, AND COMMUNICATIONS NET(Task 093-436-4086), 1

Tactical Use, 1SPLL Firing Limits, 2LLM Travel Limits, 3SPLL Reloading Balance Limits, 4Nearby Firing Area Limits, 4

Major Components, 6SPLL, 7Fire Control System, 13Primary Power System, 13Electronics Unit, 16

C3 System Net, 16TACFIRE, 17SPLL Communications Equipment, 17Platoon Leader's Digital Message Device, 19Fire Direction System, 20

REVIEW EXERCISES, 21

LESSON 2: FIRE CONTROL SYSTEM MENUS, ASSEMBLIES, AND SUBASSEMBLIES; TEST EQUIPMENT; AND THE TRAINER LP/C (Task 093-436-4086), 23

Fire Control System Menus, 23Firing Menus, 23Administrative and Maintenance Menus, 32

Hydraulic and Mechanical Assemblies of the LLM, 34Hydraulic Assembly, 34Mechanical Assembly, 34

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Primary Power Assemblies, 35

LLM Subassemblies, 35LP/C Hold-Down Latches, 35Travel Lock Actuator, 36Limit Switches, 36Boom and Hoist, 36

MLRS Rocket Subassemblies, 37Propulsion Section, 37Warhead Section, 37

Test Equipment, 38

Trainer LP/C, 39


LESSON 3: PREVENTIVE MAINTENANCE CHECKS AND SERVICES (Task 093-436-4086), 45

Crew Level, 45

Loading, 46

Organizational Level, 47Using the Extract from TM 9-1425-646-20, 47Checking Other Items, 47

Direct Support Level, 56

The 125-Percent Load Test, 56Pretest Inspection, 56Test, 57Post-Test Inspection, 58


LESSON 4: TROUBLESHOOTING AND REPAIR PROCEDURES FOR THE LLM (Task 093-436-4086), 60

Elevation and Azimuth Mechanical Drives, 60LDS Electrical and Hydraulic System Parts, 60LDS Electrical and Hydraulic System Operation, 61Troubleshooting and Repair of Drives, 64Use of Breakout Boxes, 65

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Boom and Hoist Mechanism, 66Boom Control, 66Hoist Control, 67Troubleshooting and Repair of Mechanism, 68


LESSON 5: TROUBLESHOOTING AND REPAIRING THE FIRE CONTROL SYSTEM(Task 093-436-4086), 71

Position Determining System, 71Multimeter, 71Oscilloscope, 72

Cables, 72

Line Replaceable Units, 73

Azimuth and Elevation Transducer, 73Elevation Transducer Assembly, 73Azimuth Transducer Assembly, 77Resolver Test, 78Rotary Limit Switch Adjustment, 81Switch Deck A Adjustment, 82Switch Deck B Adjustment, 84Switch Deck C Adjustment, 86Misoriented Switch Adjustment, 89Fault Isolation of Binding Gear, 96Fault Isolation of Resolver Test, 90


LESSON 6: MAINTENANCE OF THE MLRS CARRIER, M993 (Task 093-436-4086), 93

Simplified Test Equipment/Internal Combustion Engine, 93Maintenance Duties, 93Maintainability, 93

Mechanics of the Suspension System, 94

Circuitry, 94

Driver's Controls and Indicators Familiarization, 95

Preventive Maintenance Checks and Services, 113


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LESSON 7: THE DEEP ATTACK MISSILE SYSTEM: MAJOR COMPONENTS, SUPPORTING EQUIPMENT, AND TESTING, 152

Major Components, 152Missile and Missile Launch Pod/Container, 152M270 Launcher, 152

Supporting Equipment, 161Trainer Missile/Launch Pod Assembly 161Guided Missile System Test Set, 164

Surveillance and Verification Test, 170Pretest Operations, 170Test Procedures, 173Missile Maintenance, 175


EXERCISE SOLUTIONS, 184

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Lesson 1

TACTICAL USE, MAJOR COMPONENTS,AND COMMUNICATIONS NET

Task. This lesson is based on the following task from STP 9-27B14-SM-TG: 093-436-4086, Direct Support Maintenance on the Multiple Launch Rocket System (MLRS) and Associated Test Equipment.

Objective. When you have completed this lesson, you should be able to describe the major components of the MLRS, its general characteristics, and its communications net.

Conditions. You will have this subcourse book and work without supervision.

Standard. You must score at least 70 on the end-of-subcourse examination that covers this lesson and lessons 2, 3, 4, 5, 6, and 7.

TACTICAL USE

The MLRS is a highly mobile rocket launching system that can deliver a high volume of indirect fire against critical, time-sensitive targets in a short time. It is designed to supplement conventional artillery in the general support (GS) role by engaging medium-range targets. (Targets beyond the range of MLRS are to be engaged by tactical surface-to-surface missile systems; tactical aircraft; and, in some cases, off-shore conventional or missile fire.) One MLRS vehicle firing its on-board load of 12 rockets delivers 7,728 submunitions on the target. This is equivalent to three 8-inch guns in six batteries of a battalion firing three volleys.

When being used, the MLRS is in one of three areas of operation (figure 1-1), the firing area (or point), the reload area, and the hide area. The firing area is the location from which a mission will be fired. It can be a hasty position or one chosen in advance. The reload area is used to resupply the self-propelled launcher loader (SPLL) with ammunition. In figure 1-1, it is shown in the open. However, in use, it would be covered and concealed. The hide area is used for cover and concealment while the SPLL awaits a fire mission. It is generally close (50-100 meters) to a firing point.

When a fire mission is received over a digital radio link, the SPLL moves out of the hide area and travels to a firing site. The SPLL pulls into the firing site, parks, fires 1 to 12 rockets, and moves out within a matter of minutes. If all the rockets are used, the SPLL moves to a reload area for more ammunition. After reloading, the SPLL moves to a new hide area or to a second firing area, and the cycle is repeated. The SPLL is versatile and mobile, but it and the MLRS in general have certain operating limits that are discussed below.

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Figure 1-1. MLRS in Action, Showing Areas of Operation.

SPLL Firing Limits

The carrier cab, engine housing, and rocket blast all limit firing angles of the launcher loader module (LLM), and the fire control system (FCS) computes safe firing angles within these limits. Firing angles for the LLM make up a zone through which rockets can be fired safely (figure 1-2). Firing into a no-fire zone is prevented by a safety feature in the FCS.

Figure 1-2. SPLL Firing Limits.

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LLM Travel Limits

The carrier bed, the engine housing, and the interconnecting cables limit LLM moment for safety. The FCS has programmed limits to control the LLM movement. In addition, the system has mechanical limit switches to shut off the launcher drive system (LDS) if the FCS limits (figure 1-3) fail. Thus, if an FCS limit is reached when the boom controller (BC) is used, reversing the control will move the LLM out of the limit. However, if a mechanical limit is reached, the LLM must be moved out of the limit manually.

Figure 1-3. Travel Limits.

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SPLL Reloading Balance Limits

When loading or unloading full launch pod/containers (LP/C), SPLL balance is critical. There are particular LLM positions where the full LP/Cs must be loaded or unloaded one at a time (figure 1-4).

Figure 1-4. Balance Limits.

Nearby Firing Area Limits

When a rocket fires, it produces flying debris, loud noise, and toxic gas from rocket propellant. There are areas near the SPLL where unprotected personnel could be injured (figure 1-5). Personnel, in these areas must be aware of safety limits.

Figure 1-5 Firing Area Limits.

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The actual location of toxic propellant gas is determined by weather conditions at the firing site. Generally, unprotected personnel should be upwind of the SPLL. If downwind, personnel must wear nuclear, biological, and chemical (NBC) masks for maximum protection. In addition, the normal SPLL firing configuration is with two LP/Cs loaded in the LLM. The front of the LLM is designed so that the LP/C helps to keep rocket blast out of the LLM. For this reason, rockets can be fired only with two LP/Cs loaded in the LLM. If only one LP/C with live rounds is to be loaded and fired, a second, empty LP/C must be loaded in the opposite bay. See figure 1-6.

Figure 1-6. Loading LP/Cs To Fire.

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MAJOR COMPONENTS

The MLRS is made up of the SPLL, M270, which includes the LLM (M269) and the full-tracked carrier (M993) (figure 1-7); a command, control, and communications (C3) net that includes the fire direction system (FDS) in the SPLL and the battery and battalion fire direction centers (FDC); and the platoon leader's vehicle (PLV) with the platoon leader's digital message device (PLDMD) (AN/ PGS-4) (X0-1). This subcourse is concerned with systems and components in the SPLL and some of those in the FDC and the PLV.

The ammunition resupply vehicle (RS), which is the heavy expanded mobility tactical truck (HEMTT) and the heavy expanded mobility ammunition trailer (HEMAT), are associated with the system but are not really a part of it. RSVs will not be covered in this subcourse.

Figure 1-7. Major System Components.

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SPLL

The SPLL has two assemblies, an LLM and a carrier.

LLM. There are three parts to the LLM, the cage, the turret, and the base. Loaded in the LLM are the LP/Cs with rockets.

The cage (figure 1-8) is a welded aluminum assembly with 14-mm aluminum armor plate on the top and sides. The cage aligns, holds, and protects the LP/Cs during all operations. It also supports the boom and hoist assemblies that make the MLRS self-loading.

Figure 1-8. SPLL Cage.

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The turret (figure 1-9) is an aluminum weldment that supports the cage assembly and attaches to the azimuth-drive, geared-bearing outer race. The turret houses the components of the elevation drive system.

Figure 1-9. SPLL Turret.

The base (figure 1-10) is a welded aluminum structure with a rectangular lower flange that provides the structural interface with the carrier. An upper circular flange bolts to the azimuth-drive geared bearing providing the interface to the turret. The base houses the major components of the hydraulic system and the azimuth drive system.

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Figure 1-10. SPLL Base.

Launch Pod/Container. The LP/C (figure 1-11) is made of six, filament-wound E-glass fiber launch tubes supported and accurately aligned by four cast-aluminum bulkheads. The support framework is a combination of aluminum angles and channels. As a result of logistics supply studies, the LP/C was designed as a low-cost throw-away item.

Figure 1-11. LP/C, Tactical or Training.

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MLRS Rocket. The MLRS rocket (figure 1-12) is a tube-launched, fin stabilized, free-flight rocket. The rocket is 3.94 m (155 in) long, 227 mm (8.93 in) in diameter, and weighs 310 kg (682 lb). The complete rocket is assembled, checked out, and packaged in a dual-purpose launch/storage tube at the factory. This “wooden round” design provides for tactical load and fire of the rocket without troop assembly or check out.

Figure 1-12. Rocket.

MLRS Carrier. The carrier provides a highly mobile, fully tracked, lightly armored stable platform for the LLM. A pressurized cab is provided for a three-man crew (driver, gunner, and section chief). The cab design makes it possible for the crew safely and effectively to complete a fire mission from inside. The cab is protected by armor, has adjustable heating and ventilation, and attenuates noise. It hinges from the front, making maintenance easy.

There is a cab-mounted fire extinguisher with one interior and one exterior release handle.

The driver's controls, such as gauges and warning lights, are grouped according to function and importance. They include warning lights that indicate a fire anywhere in the engine compartment.

Windows. A MLRS carrier crew has excellent forward and side vision through shatterproof windows. For added safety during launches, the front windows are fitted with exterior louvered covers, and the side windows have fold-down covers. During rocket firing and for nuclear survivability, each set of louvers can be opened or closed individually by actuator levers inside the cab. During a nontactical situation, the louvers may be stowed so the crew can see better and can clean the windshield. The overhead hatch, above the commander's seat, can be opened and used as a window for added visibility and crew ventilation.

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Personnel Ventilation and Heating Systems. The personnel ventilation system is located in the left rear corner of the cab. It has a 5-micron dust filter, a 1-micron particulate filter, a charcoal filter, a bypass valve, and a fan. The bypass valve passes air through all three filters or through just the dust filter.

During normal operation the bypass valve is open, and the fan delivers 450 cfm of air through the dust filter. During rocket firing, the bypass valve is closed, and air passes through all three filters to remove toxic products from the rocket exhaust (except carbon monoxide, which is present at low concentrations). With the bypass valve closed, the system develops an overpressure of 1.2 inches of water and a flow of 150 cfm.

The cab also is equipped with M13A1 chemical, biological, and radiological (CBR) heater units and a dual-air personnel heater that recirculates cabin air.

Fire Control Unit. The FCU (figure 1-13) is at the aft end of the cage between the two LP/C bays. The area is covered by a hinged armor plate. The FCU is the main connecting link between the electronics of the FCS and the drive and monitoring equipment of the LLM. The FCU is the interface device that converts the information (such as switch position and resolver pick off) from the peripheral devices into information the electronics unit (EU) can use. Likewise, the EU computer words are converted by the FCU to information the peripheral devices can use.

Figure 1-13. Fire Control Unit.

Functions performed by the FCU are: synchronizing digital data transfer to and from the stabilization reference package (SRP); providing azimuth and elevation drive signals to the servo motors; monitoring hydraulic “fluid over temp,” low fluid level, pump pressure, “motor over temperature,” and filter status; controlling LDS power through launcher drive contactors; communicating with the remote settable fuze (RSF) during fuze setting; and communicating with the boom controller (BC) when the BC is enabled.

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Stabilization Reference Package/Position Determining System. The SRP/PDS (figure 1-14) is located at the rear of the cage between the LP/C bays, beneath the FCU. The SRP part of the system is an electrically driven device that orients itself on true North and makes a level platform for reference in computing fire mission data. The SRP is mounted on an accurately machined surface of the LLM cage that acts as the reference foundation for computing firing angles. To achieve SRP orientation, power is applied by the FCS during system start up procedures. During fire mission operations, signals from the SRP allow for launcher azimuth and elevation position corrections.

Figure 1-14. Stabilization Reference Package/Position Determining System.

Short/No-Voltage Tester. The SNVT (figure 1-15) is a built-in tester used during loading operations to test the umbilical cables to the LP/Cs. The test makes sure the cables are safe to connect to loaded LP/Cs. The SNVT is in the LLM and is protected by a cover that swings to one side when the SNVT is used.

Figure 1-15. Short/No-Voltage Tester.

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Boom Controller. The BC in the LLM permits remote control of loading and off-loading.

Fire Control System

The FCS is the heart of the MLRS operation. It is the interface between the crew, the fire direction center, and the on-board weapon system. It is the means by which the crew operates and controls the SPLL. The FCS enables the crew to execute fire missions accurately, easily, and safely. It is an electronic system of the SPLL, designed specifically to give the Army field commander easy access to, and control of, the SPLLs fire power.

The FCS is simple to operate under high-stress combat conditions. It accepts tactical fire mission assignments from the battery FDS, computes firing data, aims the launcher, and prompts the crew to fire the rocket, all automatically and in real time.

The fire control panel (FCP) (figure 1-16) in the carrier provides the crew with a visual display and push-button and switch control of the FCS; it also provides line replaceable unit (LRU) bit display and built-in test equipment (BITE) status via the plasma display.

Figure 1-16. Fire Control Panel.

Primary Power System

The primary power system (PPS) (figure 1-17) is the source of electrical power for SPLL equipment. The system consists of the battery box, electronics box, power distribution box (PDB), and connecting power cables.

The Battery Box. The battery box contains six military standard, lead-acid 12-V batteries. Four of the batteries are connected in series/parallel to provide 24 V power to the high-current launcher drive system (LDS) electric motor. The remaining two batteries, connected in series and electronically isolated from the four LDS batteries, provide power to the low-current electronic equipment.

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Figure 1-17. Primary Power System.

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Electronics Box. The electronics box (EB) is attached to the battery box. The carrier's batteries and generator are connected to the SPLL batteries in the EB. This interconnection permits the use of the carrier batteries to operate the SPLL and the use of the SPLL batteries to be charged by the vehicle's alternator. The interconnection is controlled by the carrier's launcher interconnect switch in the carrier cab. The carrier and SPLL electrical power systems are protected to prevent a fault in one system from affecting the other system. From the EB, the output of the two-battery hook-up is supplied to the FCS and to some of the communication equipment. The output of the four-battery hook-up is supplied to the PDB and the launcher drive system (LDS) contactor. The LDS contactor is a relay with contacts large enough to carry the high current needed to operate the hydraulic power supply motor. The contactor is actuated by a signal from the FCS.

Power Distribution Box. The power distribution box (PDB) (figure 1-18), mounted on the right rear of the LLM, is the main distribution point for electrical power to the SPLL systems. The PDB also distributes command signals to some of the SPLL systems.

Figure 1-8. Power Distribution Box.

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Electronics Unit

The EU is the forward end of the carrier bed and is mounted under the cage assembly (figure 1-19). It receives and processes mission data and performs the computer function of the FCS. Input to the EU is made by either the FDC through the communication equipment or by the crew using the FCP keyboard.

The EU performs all the mathematical operations required for the solution of the ballistic equations. It stores, processes, controls, and displays the coding format, and it transmits digital data on the data link.

The EU, along with the communications system, receives messages from the FDS digital RF communication link. Types of messages received include: tactical fire control data, rocket fuze setting data, meteorological data, firing point location, warhead type, number of rounds, time to fire, and target location data.

The EU has a 128 K memory. This memory is divided into three units. Memory 1 contains 96 K words of programmable read-only memory (PROM), memory 2 is made up of 16 K words of random access memory (RAM), and memory 3 contains 16 K words of nonvolatile RAM.

Figure 1-19. Electronics Unit.

C3 SYSTEM NET

The three principle elements of the MLRS communications net are the SPLL, the PLDMD in the PLV, and the battery FDC's computer. The MLRS C3 net interfaces with its higher command level C3 network through either a battalion-level tactical fire direction system (TACFIRE) or a battalion-level FDS. The system used depends upon the MLRS unit of assignment, which is either a composite artillery battalion or a pure MLRS battalion. Tactical fire control for an MLRS battalion is provided by the battalion fire direction center (FDC), which is equipped with an FDS and interfaces with a field artillery brigade.

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TACFIRE

Tactical fire control for an MLRS battery assigned to a composite artillery battalion is provided by the organic battalion-level TACFIRE, which interfaces with the division artillery TACFIRE. Technical fire control for all MLRS firing sections is provided by the SPLL onboard fire control system computer interfacing with the battery level FDS.

SPLL Communications Equipment

The SPLL uses a military standard AN/VRC-47 radio set. Three tactical vehicle intercom units are connected to the system through an AM-1780 audio amplifier. These are mounted in the vehicle crew compartment (figure 1-20). Digital messages are received by the RT-524 and sent to the FCS through a communications processor. The processor converts incoming frequency shift key (FSK) audio-pair signals to digital bit data and transmits them to the SPLL FCS; it receives data as well.

Figure 1-20. SPLL Communications Equipment.

Mission input information to the FCS can be both automatic and manual (figure 1-21). Automatic inputs are received over the SPLL radio. Manual inputs can be voice instructions received over the radio or written information on the FCP. The SPLL radio system is equipped with a communications processing unit (communications processor or CMP). The CMP electronically controls the transmitting and receiving of digital coded audio-tone radio messages (figure 1-22).

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Figure 1-21. Battalion Communications System.

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Figure 1-22. Communications Processor.

Platoon Leader's Digital Message Device

The PLDMD is a compact, portable, two-channel digital terminal (figure 1-23). When linked by standard radio or wire, this terminal receives, composes, displays, stores, and transmits digital messages. The PLDMD can act as a relay between FDC and SPLLs, can link with TACFIRE on a limited basis, and can act as a degraded FDC if the FDC fails. The PLDMD is used primarily by the MLRS platoon leader to monitor transmissions to and from the three SPLLs in the command. The PLDMD weighs less than 10 lbs and measures 11 x 8 x 4 in.

Figure 1-23. Platoon Leader's Digital Message Device.

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Fire Direction System

The MLRS uses a battery computer unit (BCU), which is called the FDS in the MLRS, for fire direction at the battery level and at the battalion level for the MLRS (27-launcher) battalion. The FDC is made up of FDS with MLRS-peculiar software, COMSEC equipment, and standard military radio equipment mounted in an M577 vehicle (figure 1-24).

The FDS provides tactical fire control and is linked with the SPLL on-board computer, TACFIRE, and the PLDMDs. The FDS accepts fire mission requests from higher headquarters, selects the battery/SPLL to fire (dependent upon battery or battalion FDC use), and transmits necessary data, such as meteorological data (MET) and target (TGT).

Figure 1-24. Fire Direction System.

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REVIEW EXERCISES

Circle the letter of the correct answer to each question.

1. Which assembly of the MLRS houses the major components of the hydraulic system?

a. Turret assembly.b. Base assembly.c. Cage assembly.d. Boom assembly.

2. Which box of the MLRS provides the interface between the carrier electrical system and the primary power system (PPS)?

a. Battery box.b. Power distribution box.c. Electronics box.d. LDS contactor box.

3. Which of the following positions is within tolerable limits for loading one full LPC at a time into the cage?

a. 1,600 mils.b. 3,200 mils.c. 90 mils.d. 400 mils.

4. Which radio set does the SPLL use?

a. AN/VRC-47.b. AN/VRC-46.c. AN/VRC-13.d. AN/VRC-22.

5. Which component of the MLRS receives and processes mission data?

a. Electronics box.b. Electronics unit.c. Fire control panel.d. Fire control unit.

6. The short/no-voltage tester (SNVT) is a built-in tester used during what operation?

a. Loading.b. Start-up.c. SRP/PDS alignment.d. Resolver alignment.

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Recheck your answers to the Review Exercises. When you are satisfied that you have answered every question to the best of your ability, check your answers against the Exercise Solutions. If you missed two or more questions, you should retake the entire lesson, paying particular attention to the areas in which your answers were incorrect.

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Lesson 2

FIRE CONTROL SYSTEM MENUS, ASSEMBLIES,AND SUBASSEMBLIES; TEST EQUIPMENT;

AND THE TRAINER LP/C


Objective. When you have completed this lesson, you should be able to describe the operation of the FCS and MLRS assemblies, subassemblies, trainer LP/C, and ancillary equipment.



FIRE CONTROL SYSTEM MENUS

You need to know the detailed operation of the system's menus because you and your repairers use them for calibration, repair, and verification of repair. Running these menus is the only self-test the system has.

Firing Menus

Starting Up. Ensure that communication equipment and arm and fire switches are off. Set master power switch on. Set launcher interconnect switch on. Turn on fire control panel system power. When ensure language prompt appears on the display screen, select appropriate language prompt, and press execute.

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Inputting Start-Up Data. The next prompt that will appear after execute is pressed will be the index menu. From this menu, select option zero (0), which is the start-up data menu. The start-up data selection field is displayed. Select the system start up, option number zero (0), and press store.

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The first field in the system start-up routine is the easting field (part of determining position). The location coordinates entered for this field are the present location of the SPLL at the time of start up. Enter the easting numbers written on your SPLL start-up data card (figure 2-1) and press store.

The northing, altitude and grid zone are all inputted the way the easting was. Once all the inputs are stored, the next prompts will appear. They are giving you the status of the rocket.

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Figure 2-1. Local Form, MLRS SPLL Start-Up Data Form, FS Form 1330 (Test), Available from Ft. Sill, OK.

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The last field requires time input. Once this is complete, the next prompt tells you the SRP is aligning and how long it will take. The displayed time counts down until the SRP is aligned. The maximum time you can have is 8 minutes.

During SRP alignment, press index and select start up data. When the start up data menu appears, select the communications start up option, which is 1, and press store. Once store has been pressed, the prompt on the display screen changes.

There are 32 fields in the communications start up. The only fields used are fields 1 through 25. All information to be inputted is taken off of the MLRS SPLL start-up data card. For each field, enter the appropriate number and press store. All fields are entered in the same manner. Upon completion of the communications start up, the next prompt will be either SRP aligning--time-to-go or SRP ready.

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Inputting PDS Data. In order to gain access to the PDS, start up from the last prompt with the index key. This displays the index menu again. Select start up data, option zero (0). On the new display, notice that PDS start up is option 2. Press number 2 and store keys.

The first field to be seen is the odometer scale factor. The numbers for input are found on the MLRS SPLL start-up data card. Entries for azimuth crab angle and elevation crab angle are inputted the same.

Inputting Fire Mission Data. Press the index key for the index menu to be displayed. From the index menu, select the auxiliary menu, option number 8. Press execute. The auxiliary menu will be displayed, and, from it, select the fire-mission routine, option number 4. Press execute key. The first field in the fire mission routine will be displayed. The target number is for editing only. There is no input for this field. To get the next prompt, press next field. (This also pertains to move easting, move northing, and move grid zone.) Once next field is pressed, the first prompt seen is warhead. All

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information needed for input of fire mission data is obtained from the SPLL tactical fire mission data card (figure 2-2). Each field is self explanatory and all information is inputted the same way.

Following Firing Sequence. The entries for manual fire mission have now all been inputted, and the first prompt in the fire mission routine is displayed.

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Figure 2-2. Local Form, SPLL Tactical Fire Mission Data, FS Form 1329 (Test), Available from Ft. Sill, OK.

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Press initiate when the crew has parked the vehicle at the appropriate heading. The next prompt appears at the same time the fire control system calculates all fire mission data.

When LCHR LAY (launcher lay) is pressed, the fire control system recalculates fire mission data, then unlocks the travel locks. The LLM elevates to 302 mils, then traverses left or right to the first firing point. When movement stops in azimuth, the LLM elevates or depresses to the first firing point. When the degrees of both azimuth and elevation are correct, after a few seconds, the display adds one line, arm rockets. The operator flips the toggle that arms the rocket. The system sets the fuze of the rocket, and the display adds another line, fire rockets. The operator now flips the toggle switch that fires the rocket.

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MM4806, Lesson 2

Closing Down. When the fire mission is complete, the next prompt tells the crew to stow LLM. When LLM stow is pressed, the LLM starts to move to the stow position. When the LLM is stowed, the LLM stowed prompt appears. The fire mission is complete, and the crew moves the system to the reload area.

Administrative and Maintenance Menus

Index. The index menu initially has five menus that are functional when power is first applied. After SRP has aligned, the index menu increases its memory to 10 functional menus (adds five).

Boom Control. With the boom control menu the crew tells the SPLL how to adjust itself for reload or repairs. It also allows for manual boom control.

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MM4806, Lesson 2

Rocket Status. When this menu is called up, it shows the status of all rockets.

D = Dud = Good

Blank Space = Fired H = Hangfire

Update PDS. This menu is called up when the PDS is to be updated or calibrated by the crew

Auxiliary. The auxiliary menu lists additional operating routines for normal SPLL operation.

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MM4806, Lesson 2

HYDRAULIC AND MECHANICAL ASSEMBLIES OF THE LLM

Hydraulic Assembly

The hydraulic system assembly is a power supply that is in three sections as follows (figure 2-3):

Reservoir. This is the container for the hydraulic fluid supply.

Hydraulic Pump. The MLRS system uses a Vickers radial piston pump with nine pistons. The pump also has two, 5-micron filters.

Electric Motor. The MLRS hydraulic motor is a constant displacement, seven-radial piston motor controlled by electrical servo motors.

Figure 2-3. Hydraulic Assembly.

Mechanical Assembly

Azimuth and Elevation Servomotors. The azimuth (AZ) and elevation (EL) servomotors are the same, but they are not interchangeable because they are bolted to their transmissions. The motor is a seven-piston, constant-displacement, electrical-valve-controlled motor. The servomotors provide the interface between the hydraulic and mechanical components.

Elevation Angle Drive. The elevation angle drive is a fixed-displacement, bidirectional, radial-piston motor. Incorporated in the motor are a series of relief and check valves to control internal hydraulic fluid flow during different cycles of motor operation.

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MM4806, Lesson 2

Azimuth Drive. The azimuth drive is the same as elevation angle drive except that it is not interchangeable.

Elevation Actuators. The elevation actuators are mechanical devices that raise or lower the cage. They are connected to the elevation angle drive by drive shafts.

Speed Reducer. The speed reducer is geared for a low traversing ratio. It can be operated hydraulically or manually by a flex cable. The speed reducer allows for smooth operation of the cage assembly when traversing left or right.

PRIMARY POWER ASSEMBLIES

Battery Box. The MLRS battery box (BB) houses six lead acid batteries. The fire control system uses two batteries connected in series to provide 24 V of low amperage. The launcher drive system uses four batteries connected in series and parallel combined to provide continuous -24 VDC high amperage. The batteries are charged by the vehicle charging system.

Electronics Box. The electronics box (EB) is attached to the BB. It relays voltage to the rest of the system.

Power Distribution Box. The power distribution box (PDB) distributes the high amperage to the left and right booms, the left and right hoists, and the hydraulic system.

LLM SUBASSEMBLIES

LP/C Hold-Down Latches

The two LP/C hold-down latches are hand-operated and hold the LP/Cs in place inside the LLM cage. The LP/C hold-down latches are operated from the rear of the LLM (figure 2-4). The MLRS repairer is responsible for adjusting the latches.

Figure 2-4. LP/C Hold-Down Latches.

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MM4806, Lesson 2

Travel Lock Actuator

The travel lock actuator (figure 2-5) is the mechanism that locks or unlocks the transport locking system. If there's an electrical failure, the actuator can be manually locked or unlocked. Its main purpose is to secure the cage while in transport so damage does not occur to the LLM and its assemblies.

Figure 2-5. Travel Lock Actuator.

Limit Switches

The limit switches (figure 2-6) prevent the system from overtravel, which could cause damage. The 1.25, 15, 27, 62.2, 73, 106, and 196 limit switches prevent damage to the SPLL while it is in elevation or azimuth movement. The boom-out limit switch keeps the booms from extending beyond their limits.

The boom-in limit switch keeps the boom from damaging other components in the cage when the boom is retracted. The hoist limit switches keep the hoist motor from winding the cable too tightly or from letting all the cable out of the hoist drum. The cage down limit switch sends a signal through the FCS to lock the cage.

Boom and Hoist

The boom-and-hoist assembly is a telescoping beam, hoist carriage, and a hoist. Each boom has two outer fixed beams and two telescoping beams. The booms are extended and retracted by a pair of ball screw actuators attached to the telescoping beams and driven by an electric motor. Note: Remember that the hoist carriage assembly moves twice as fast as the telescoping beam. The hoist carriage is made up of the hoist control box and the hoist motor/drum assembly. Manual drive inputs are provided for both the booms and hoists in case there's an electrical failure.

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MM4806, Lesson 2

Figure 2-6. Limit Switches.

MLRS ROCKET SUBASSEMBLIES

Propulsion Section

The MLRS rocket propulsion section is a solid-propellant rocket motor. The rocket motor uses hydroxyl terminated polybutadine (HTPB) solid propellant, which is molded to the inner wall of the motor skin. Two spin lugs and two rider buttons interface the aft end of the rocket motor with spin rails on the launch tube interior wall. The spin rails initiate a 10-12-revolutions-per-second, counterclockwise spin for the missile's flight stability.

Warhead Section

There are two warheads that can be used. One delivers M77 submunitions and the other delivers German-developed AT-2 mines (figure 2-7).

M77 Submunitions. Six hundred forty-four individual M77 munitions are packaged end-to-end in a honeycomb matrix around a centered, lead-lined, warhead burst charge. Four V-shaped grooves help split the warhead's aluminum shell. These grooves are cut along the entire length of the warhead's outer surface.

AT-2 Mines. The AT-2 mine warhead is the same as the M77 submunition warhead except for its payload, which is 28 mines.

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MM4806, Lesson 2

Figure 2-7. Contents of Warhead.

TEST EQUIPMENT

Breakout Boxes. The MLRS breakout boxes connect the cable assemblies with the electronic LRUs and bring individual data lines to test points for measurement of voltages, resistances, and continuity.

The MLRS has five breakout boxes: fire control panel, power distribution box, hoist, boom, and transducer. All of the breakout boxes are used on the system except the transducer breakout box, which is used as part of the bench setup in a GS shop.

Audio Oscillator. The audio oscillator is a power supply for the testing and repair of the elevation or azimuth transducers. It is connected to the transducer breakout box.

Synchro Angle Indicator. The synchro angle indicator is used strictly for the testing or repair of the elevation or azimuth transducers. It tells the repairer the degree at which the transducer is sitting (0 to 360). The indicator is connected to the transducer breakout box.

Multimeter. The multimeter used by the repairer is a Fluke digital multimeter that can measure AC and DC voltage, resistance, and milliamps.

Oscilloscope. The MLRS uses a Tektronix 212 oscilloscope. It checks square waves for the position determining system and sine waves for the transducers.

Test Cables. There are two test cables the repairer uses. The limit switch test cable checks continuity of the limit switch connected to the test cable. The other test cable connects the transducer breakout box to the synchro angle indicator.

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MM4806, Lesson 2

TRAINER LP/C

This is an MLRS-associated piece of training equipment. It is used to keep both the crew members and DS support personnel well trained. In your job, you have to know how to set up a training session for repairers.

Training is set up by the fault insertion panel (figure 2-8). The panel, in rocket tube number 4, allows the crew chief to insert a fault or faults into the LP/C for crew training during a simulated fire mission.

Figure 2-8. Trainer of LP/C.

The trainer can put six different faults into the fire control system through the LP/C simulator assembly. The position of switches on the fault insertion panel determines which fault is inserted. The following paragraphs explain how the switches cause the fault indications.

When the rocket-4 fuze switch is placed at dud, the fuze test circuit is opened. This causes the fire control system to sense a dud fuze. The FCP in the SPLL displays a D for rocket number 4 during a rocket status display.

When the rocket-4 status switch is placed in open, the rocket status signal is interrupted before it reaches the circuit card simulator. This simulates an empty rocket tube number 4.

Positioning the rocket-4 status switch to hangfire completes the number-4 igniter hi-circuit when the fire switch on the FCP is actuated. A path is complete through the normal side of the rocket-4 misfire switch, the hangfire side of the rocket-4 status switch, and back to the fire control system. This simulates a firing pulse sent to the rocket motor. At the same time, a signal

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MM4806, Lesson 2

is sent through the normal side 4. A circuit path is complete for digital return, simulating a rocket still in tube number 4. The fire control system in the SPLL interprets this as a hangfire by sensing that a firing pulse was sent to the rocket and that a rocket is still in the tube.

Positioning the rocket-4 misfire switch to misfire interrupts the igniter high-firing pulse for tube number 4 before it reaches the simulator circuit card, simulating a firing pulse sent by the fire control system but not received by the rocket motor.

The rocket-2 misfire switch interrupts the igniter highfiring pulse for tube number 2 before it reaches the simulator circuit card, simulating a firing pulse sent by the fire control system but not received by the rocket motor.

When the rocket pod identification switch is open, it interrupts the identification signal. The fire control system senses and registers an improper umbilical cable connection.

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MM4806, Lesson 2

REVIEW EXERCISES


1. From which menu is the start-up date selected?

a. Auxiliary menu.b. Test menu.c. Index menu.d. Message menu.

2. Which two switches must be off before you perform fire control start-up procedures?

a. Arm and fire.b. RFU and FCP.c. Master power and interconnect.d. Arm and RFU.

3. What is the first field you see when performing system start up?

a. Northing.b. Altitude.c. Grid.d. Easting.

4. During communications start up, which fields are not used?

a. 24-32.b. 26-32.c. 25-32.d. 23-32.

5. When you press the LCHR LAY key how many mils must the LLM elevate before traversing?

a. 302.b. 240.c. 360.d. 180.

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MM4806, Lesson 2

6. Which menu allows the crew to control manually the movement of the LLM?

a. Auxiliary menu.b. Boom control menu.c. Test menu.d. Index menu.

7. Which of the following provides the interface between hydraulics and mechanical components?

a. Servomotors.b. Speed reducer.c. Actuator.d. Angle drive.

8. The fire control system has how many batteries?

a. One.b. Three.c. Four.d. Two.

9. What is the purpose of the travel lock actuator?

a. Secures the LP/Cs.b. De-energizes the suspension lockout.c. Secures cage for transport.d. Keeps crew from moving SPLL.

10. Which limit switch sends a signal to lock the travel lock assembly?

a. 196.b. 27.c. Hoist up.d. Cage down.

11. The spin rails initiate a spin rate of how many revolutions per second?

a. 4-6.b. 10-12.c. 7-10.d. 15-18.

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MM4806, Lesson 2

12. How many breakout boxes are used with the MLRS?

a. Eight.b. Five.c. Three.d. Six.

13. The audio oscillator serves as a power supply for testing or repairs of what item below?

a. Breakout boxes.b. All MLRS cables.c. EL and AZ transducers.d. All MLRS test equipment.

14. The synchro angle indicator is used for testing what item?

a. AZ and EL transducers.b. Stabilization reference package.c. Positioning determining system.d. AZ and EL gyros.

15. How many MLRS test cables are there?

a. Three.b. Fourc. Two.d. Five.

16. The fault insertion panel is located in what tube of the LP/C?

a. Two.b. Fourc. Six.d. One.e. Three.f. Five.

17. If you received an improper umbilical cable connection prompt across the fire control panel, which switch on the fault insertion panel would cause this?

a. Fuze.b. Rkt Status.c. LP/C Ident.d. Temp.

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MM4806, Lesson 2

Recheck your answers to the Review Exercises. When you are satisfied that you have answered every question to the best of your ability, check your answers against the Exercise Solutions. If you missed five or more questions, you should retake the entire lesson, paying particular attention to the areas in which your answers were incorrect.

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MM4806, Lesson 3

Lesson 3

PREVENTIVE MAINTENANCE CHECKSAND SERVICES


Objective. When you have completed this lesson, you should be able to describe the proper preventive maintenance checks and services (PMCS) for the MLRS at the crew, organizational, and direct support levels.



CREW LEVEL

For each check or service, you will find what indicates the fire control system or launcher loader module is NOT ready to be used. The list is taken from TM 9-1425-646-10. Make sure all cautions, warnings, and other safety measures are followed.

Travel Lock Hooks. Travel lock hooks are not fully under rollers, and actuator is extended.

Load Test Date. Annual load test date for LP/C boom and hoist assemblies has expired.

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MM4806, Lesson 3

Hydraulic Lines and LDS Components. Any hydraulic line or component has a class III leak. For a definition of a class III leak, look ahead to Checking Other Items in this lesson. The definition is under the heading: Hoses and Fluid Lines.

System Start Up. SRP aligning, timing-to-go prompt, or start-up complete, SRP ready prompt is not displayed. Communications processor does not accept overhead message and inconsistent communications data error prompt is displayed.

Communications Check. Messages cannot be sent. Communications processor sends a communications processor message back to the FCS and causes a no response or an invalid serial number prompt to be displayed when you try to send a message.

Loading.

The LDS does not come on and move LLM to loading position selected.

Any fault prompt is displayed.

There are broken, bulging, or kinked strands (will foul hoist pulleys and interfere with hoist operation).

SPLL is not able to load or unload LP/Cs from either bay.

SNVT light or either the left or right umbilical test no go light comes on.

LP/C in either bay cannot be latched in place.

PDS Update. Any SPLL location data (easting, northing, or altitude) is in error by more than 85 meters after traveling 6-8 kilometers with loaded LP/Cs. PDS data bad prompt is displayed while SRP/PDS is turned on.

Radio Antennas. Antenna or antenna mounting base is damaged. Antennas have heavy rocket motor exhaust deposits that stop or interfere with the ability to send or receive messages.

Umbilical Cables. Cable connector adapter has broken or damaged pins. Cable connector adapter key or guides are badly worn and can keep cable from making proper connection.

Hoist Assembly. Neither hoist assembly is able to load or unload LP/Cs. Hoist pulley assembly cannot be positioned to M26 position.

Hydraulic Fluid Level. Fluid level indicator red band is at or below the refill mark.

Heat Exchanger. There is something stopping or interfering with the air flow, and it cannot be removed.

Azimuth Drive and Elevation Angle Drive. Any component has a class III leak. For a definition of a class III leak look ahead to Hoses and Fluid Lines.

Elevation Actuator Gear Housing. Actuator gear housing has a class III leak with a leak rate more than three drops per minute.

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MM4806, Lesson 3

Batteries. Batteries are cracked or broken, or terminals are loose.

Hoist Cables. A cable has a broken strand, bulge, or kink.

Limit Switches. The limit switch on the plunger does not operate properly.

ORGANIZATIONAL LEVEL

Using the Extract from TM 9-1425-646-20

The order of your repairers inspection and checks are numbered in the item column in the following extract, figure 3-1. Do them in the order shown. This is the same number that you will enter in the TM manual column of DA Form 2404.

Each item to be inspected includes instructions for correcting problems you may find. These instructions might refer you to the next higher maintenance level or refer you to a maintenance or troubleshooting paragraph in the TM. Sometimes the instructions are how you can correct the problem yourself. You must record on a DA Form 2404 all the deficiencies that you find during PMCS.

If you correct the deficiency, record your corrective action on DA Form 2404. Any deficiency that you cannot correct you must report to next higher maintenance level on a DA Form 2407. For complete instructions on filling out forms, refer to DA Pam 738-750 (not necessary for this subcourse).

Checking Other Items

The following are common items that are not shown on the PMCS table. They do need to be checked ahead of time, however, because they are basic and essential to the continuing operation of the MLRS.

Bolts, Nuts, Screws, Clamps. If any are loose, tighten them.

Welds. Look for chipped paint, rust, or gaps where parts were welded together. Touch up chipped paint. Clean rust and repaint. Notify next higher maintenance level of broken welds.

Electrical Cables and Connectors. Look for cracked or broken insulation, bare wires, and loose or broken connectors. Tighten loose connectors. Notify next higher maintenance level of damaged wiring or connectors.

47

Hoses and Fluid Lines. You can continue to operate equipment with class I or II leakage. When this happens, continue to check the hydraulic fluid level in the reservoir. You can expect some leakage from certain seals and weep holes in LDS components. The azimuth and elevation drive motors and the hydraulic power supply will have class III leaks at their seals, which drain into their scavenge reservoirs. No other class III leak is permitted. Check for leaks and bent or damaged lines. Tighten loose connectors. Notify next higher maintenance level of broken or damaged lines or of connectors that continue to leak after being tightened. The definitions of class I, II, and III leaks are as follows:

Class I - Seepage of hydraulic fluid (as indicated by wetness or discoloration) not great enough to form drops.

Class II - Leakage of hydraulic fluid great enough to form drops but not enough to cause drops to drip from item being checked or inspected.

Class III - Leakage of hydraulic fluid great enough to form drops that fall from the item being checked or inspected.

Paint. Check for chipped paint. Touch up paint where it's required.

In the following extract from TM 9-1425-646-20, figure 3-1, there may be other TMs or appendixes referred to. Since you do not need them to complete this subcourse, they have not been included.

Figure 3-1 Extract from TM 9-1425-646-20: Organizational Preventive Maintenance Checks and Services.

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MM4806, Lesson 3

Figure 3-1. Extract from TM 9-1425-646-20: Organizational Preventive Maintenance Checks andServices--continued.

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MM4806, Lesson 3

Figure 3-1. Extract from TM 9-1425-646-20: Organizational Preventive Maintenance Checks andServices—continued.

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MM4806, Lesson 3


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MM4806, Lesson 3


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MM4806, Lesson 3

Figure 3-1. Extract from TM 9- 1425-646-20: Organizational Preventive Maintenance Checks andServices--continued.

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MM4806, Lesson 3

Figure 3-1. Extract from TM 9-1425-646-20: Organizational Preventive Maintenance Checks andServices--continued

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MM4806, Lesson 3


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MM4806, Lesson 3

DIRECT SUPPORT LEVEL

At the DS level, the MLRS repairer uses both TM 9-1425-646-10 and -20 manuals to perform PMCS on operational readiness float equipment.

THE 125-PERCENT LOAD TEST

At organizational and DS levels, the repairer also performs an annual PMCS test that is particularly important, especially after repair of the hoist or boom assemblies: the 125-percent load test.

Pretest Inspection

Perform SPLL start-up procedures, and drive the SPLL to the place where the test loads have been prepositioned. Place the SPLL so the loads may be picked up from 1,600 mils (90 ) azimuth position. Using the fire control panel, position the LLM to 1,600 mils. Engage the suspension lockout and enable the boom controller. Go to the rear of the LLM, and remove the BC from the storage compartment at the left rear of LLM as follows:

Release both latches on BC storage compartment door, and swing door open. Unfasten strap holding BC in holder inside the door, and carefully remove BC from the holder on the door. Remove and uncoil the BC cable.

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MM4806, Lesson 3

On the BC, select “both position” on the boom/hoist selection switch, then extend both booms. Traverse the LLM until the hook-and-pulley assemblies, when lowered, will clear test loads. Lower both hook-and-pulley assemblies while making sure the cable is operating smoothly and without slack.

Inspect both cables by lifting the cable off the pulleys in the hoist carriage and the hook-and-pulley assemblies. Examine pulleys for rim nicks that might cut the cable and for other damage. Spin pulleys to verify that they turn freely. Examine the hook lock mechanism for damage and proper operation. Using the BC, raise both hook-and-pulley assemblies until they clear the test loads. Traverse the LLM until the hook-and-pulley assembly for one boom is directly above test-load lifting bar.

Test

Using the BC, lower one hook-and-pulley assembly and attach it to the test load.

After making sure all personnel are clear of the test load, raise the test load about 1 ft (1/3 m) off the ground. Hold the test load in this position for 30 sec while observing the cable for evidence of slippage. Using the BC,

lower the test load and disconnect the hook-and-pulley assembly. Raise the hook-and-pulley assembly, then retract the boom. Using the BC, traverse the LLM so the other hook-and-pulley assembly is directly over the test load lifting bar. Repeat the test procedure for the second boom and hoist. Replace the BC in its compartment and stow the LLM. Disengage the suspension lockout.

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MM4806, Lesson 3

Reposition the SPLL to a position to load the test loads from 3,200 mils (180) azimuth. Position LLM to 3,200 mils. Engage the suspension lockout.

Using the BC, extend both booms. Lower the hook-and-pulley assemblies, one at a time, while making sure the cable runs smoothly. Attach the hook-and-pulley assemblies to the test loads, and clear all personnel from the test area. Raise both test loads together until the hoist-up limit switch stops the operation. Hold both of the test loads in this position for 30 sec while observing the cables for any evidence of slippage and the cage-to-turret gap.

With one hand placed on the side of the cage, use the BC to rotate the cage in either direction about 36 mils (2 ), and make sure that the cage stops moving promptly when you release the BC switch.

Using the BC, lower the LLM to the horizontal position. Then lower the test loads and disconnect the hook-and-pulley assemblies from the test loads.

Post-Test Inspection

Using the BC, raise both hook-and-pulley assemblies enough to clear the test loads. Traverse the LLM until the hook-and-pulley assemblies clear the test loads, then lower the hook-and-pulley assemblies. Inspect the hoist cables and pulleys and the boom structures for warped or bent beams. Using the BC, raise the hook-and-pulley assemblies, retract both booms, and stow the cage. If the SPLL has passed, stencil the date of the test on the upper left forward side of the cage.

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MM4806, Lesson 3

REVIEW EXERCISES


1. What is the class and leakage of hydraulic fluid that is great enough to form drops but not great enough to drip from item being checked or inspected?

a. IV.b. II.c. I.d. III.

2. The order of the inspection and checks should be according to which of the following?

a. The DA Form 2404.b. What you first find wrong.c. The order in the TM.d. The first interval given in the TM.

3. Replace the EU if the azimuth resolver indication on the FCP is not between which figures in item V?

a. -1325 and -1334.b. -1335 and -1345.c. -1324 and -1334.d. -1334 and -1345.

4. The test load has been raised 1 foot off the ground. How many seconds must the test load be held in this position?

a. 15.b. 25.c. 20.d. 30.

5. Before starting travel limit switch checks, make sure that, with the LLM in stow, the elevation resolver indication on the FCP is how many mils?

a. -1 to +1.b. -3 to +3.c. -4 to +4.d. -2 to +2.


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MM4806, Lesson 4

Lesson 4

TROUBLESHOOTING AND REPAIRPROCEDURES FOR THE LLM


Objective. When you have completed this lesson, you should be able to describe the proper troubleshooting and repair procedures for the elevation and azimuth mechanical drives and for the boom and hoist mechanisms in the LLM.



ELEVATION AND AZIMUTH MECHANICAL DRIVES

The elevation and azimuth mechanical drives are part of the launcher drive system (LDS) and are run electrically and hydraulically. Other parts include the hydraulic power supply, the servomotor, valve assemblies, and related electronics components. The related electronics components, the LDS contactors, give the LLM movement.

The azimuth mechanical drive includes the speed reducer and the geared bearing. The elevation mechanical drive includes the transmission/brake angle drive unit, propshafts, and actuators.

If the drive systems fail, the crew will not be able to position the cage manually to fire the rockets. The MLRS repairers you supervise are responsible for isolating malfunctions in the system in forward areas as members of direct support contact teams.

LDS Electrical and Hydraulic System Parts

LDS Electric Motor. The LDS motor is a 12.1 hp, ±18-28 VDC motor, rated 4,000 rpm at ±21 VDC. Steady-state power consumption is 12 kW. The motor drives the hydraulic pump to provide pressure to the azimuth and elevation servo valves. The motor is controlled by the LDS contactor and limit switch system.

LDS Contactor. The contactor is a large power relay with contacts that can carry the high-current demands of the LDS electric motor (1,650-amp surges). The contactor is actuated by the FCS-generated command, LDS ON CMD, from the FCU. The limit switch system can interrupt current to the contactor.

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MM4806, Lesson 4

Limit Switch System. The LDS limit switch system is made up of single-pole switches connected in series with the LDS contactor circuit. They interrupt LDS power if the FCS fails to control LLM movement. The switches can be actuated mechanically if the LLM moves into positions that would cause damage to any MLRS system mechanical or electrical component.

Azimuth and Elevation Servo Valves. These are electrically operated valves controlled by command signs from the FCS. They direct hydraulic pressure to the azimuth and elevation servo motors.

Elevation Pressure Regulator. This is a solenoid-operated valve that reduces pressure to the elevation servo valve during the last 35 mils of down movement during stow. It prevents damage to mechanical actuators and is controlled by FCS command signals.

Azimuth Freewheel Solenoid. This is another solenoid-operated valve that removes hydraulic operating pressure from the azimuth servo valve for the last 35 mils of down movement during stow to prevent damage to the cage centering probe. It is also controlled by FCS commands.

Azimuth and Elevation Resolvers. The azimuth and elevation resolver are position indicator devices used during stow and reload to provide servo loop closure to the FCS. The resolver shafts are coupled by gear train to the LLM's azimuth and elevation mechanical axes. They are adjusted when they are installed on the carrier cab and bed and are 0 mils when the LLM is stowed. The FCS supplies an AC, 400-Hz, 18-V signal on the resolver S1 and S3 terminals. This voltage is induced on the R1 to R4 windings and is determinate in phase and amplitude to the direction and amount of movement of the resolver shaft. The resolver position output from R1 to R4 windings is convened to digital position data by an R/D converter and is supplied to the FCS as servo loop feedback. The resolvers are also used to back up the SRP/PDS position signals to the FCS during firing. The two position signals are compared and, if they do not match within ±5 mils, generate a fault message.

Cage Transport Latch Actuator. This is an electric motor-driven screw jack used to lock and unlock the transport latch, which secures the cage for travel. It is controlled by command signals from the FCS.

Boom Controller. This is a hand-held remote switch box used to control LLM and boom and hoist movement during reloading and maintenance.

Hydraulic Heat Exchanger. This is a simple oil-cooler device that uses a fan-cooled radiator through which the return hydraulic fluid is routed. The heat exchanger fan circuit is connected with the LDS electric motor in parallel and runs whenever the LDS motor is on.

LDS Electrical and Hydraulic System Operation

Prefire. During tactical fire mission operations, after the crew has moved the SPLL to the designated firing point and has parked within the proper azimuth and slope limits, the fire control panel displays a prompt, when parked press INIT. After INIT is pressed, the prompt, to continue mission press LCHR lay, is displayed. When the launcher lay key is pressed, the fire control system initiates the necessary commands to unlock the LLM cage and move it to the firing azimuth and elevation.

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MM4806, Lesson 4

The fire control unit issues a cage unlock command to the PDB. This command provides a return for the cage unlock (K4) relay in the PDB. The +24 VDC goes from the positive bus of the PDB to the transport latch actuator retract circuit via PDB connector J3, pins R and J. Return is via PDB connector J3, pins T and H. When the actuator completes its travel, a limit switch in the actuator opens the retract circuit and closes the LDS relay +24 VDC connection from the actuator limit switch to the LDS on relay X1 pole via pin N of the PDB J3 connector The cage unlock signal is also routed to the FCS via PDB connector J1, pin 72, to the FCU as a signal that the cage is unlocked.

The FCU then issues an LDS on command to the PDB to provide a return for the LDS on relay K2. When PDB K2 closes, +24 VDC is provided to the X2 anode pole of the LDS contactor relay via PDB connector J4, pin 23, and the limit switch circuitry.

The LDS limit switches are connected in a series-parallel combination, with the +24 VDC routed to the LDS contactor relay from the PDB K2 relay. The limit switch system interrupts LDS power if the LLM moves into azimuth or elevation angles that would damage the SPLL mechanical components. Movement of the LLM is controlled by software in the FCS. The limit switch system functions only if the FCS fails to control the LLM.

There are four azimuth limit switches. Three of these are in the azimuth position transducer assembly (they have limits of 73, 106, and 196). The remaining azimuth limit switch (1.25) is on the turret and is actuated by a cam on the base assembly.

There are also four elevation limit switches. Two, 15 and 27, are mounted on the right rear hinge point of the turret and are operated by cams on the cage. The other two are right and left 62.2 switches and are inside the elevation (ballscrew actuators).

From the stowed position, the 1.25 azimuth limit switch limits azimuth movement until the cage has been elevated to at least 15. This is to allow clearance between the front of the cage and the carrier cab and engine components. When the cage has been traversed to 73, the 15 minimum elevation limit is bypassed. After 106 in azimuth has been reached, elevation is limited to a maximum of 27 to prevent interference between the rear of the cage and the carrier's components. The 196 azimuth switch prevents azimuth movement past that point to protect the electrical cables that interface the base with the turret and cage. The ballscrew actuator 62.2 limit switches keep the actuators from extending to the mechanical limits that damage the actuator.

The return for the K2 relay is by the PDB connector J4, pin 24. When the contactor relay closes, +24 VDC from the batteries pass through the resistor contacts to the LDS motor for 50 msec only, because there's a time delay device in the relay. This delay allows the rest of the circuit to initiate. The resistor circuit is necessary to limit surge current to 1,650 amp. When the time delay is over, the battery-direct contacts route battery current directly to the motor through the M terminal. The LDS motor then runs, driving the hydraulic pump that, in turn, creates operating pressure levels after about 1 sec. Afterwards, the FCS reviews the built-in test (BIT) for LDS.

The LDS built-in test equipment (BITE) is six sensor switches installed in the hydraulic power supply components. They monitor: hydraulic pump

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pressure, reservoir fluid level, hydraulic fluid temperature, hydraulic fluid filter cleanliness, and the electric motor brush temperature. The sixth sensor is installed in the elevation valve module to monitor elevation hydraulic pressure when the LLM is stowed.

Abnormal LDS conditions actuate the sensor switches and provide a malfunction display on the gunner's fire control panel. All prefire activity stops until the malfunction is fixed.

If the BIT finds nothing wrong, the FCS will issue an elevation signal from the FCU to the elevation servo valve through the PDB connector J1; pins 46, 47, 48, and 56; and through PDB connector J4; pins 3, 4, 25, and 26. The signal will be software controlled to elevate the LLM to 310 mils (±8 mils). During this initial elevation, the LLM reference angle comes from the azimuth and elevation resolvers, and the azimuth position is maintained at 0 mils (±2.5 mils). Once elevation has been achieved, the FCS commands azimuth movement of the LLM to the firing azimuth through PDB connector J1; pins 49, 50, 51, and 52; and connector J4; pins 27, 28, 29, and 30; to the azimuth servo valve. The FCS then commands the LLM to the firing elevation through a reiteration if it has not already been achieved. During the final firing alignment, the LLM angle reference is supplied by the SRP/PDS. If an arm command is not issued to the crew and acted upon within 10 sec after the aim point has been reached, the FCS shuts the LDS down by removing the LDS on command. When an arm command is issued and the arm switch set to arm, the LDS is powered up and remains active until all selected rockets are fired.

Fire. During firing the FCS monitors the LLM's position, using SRP reference signals. It also issues appropriate azimuth and elevation commands to the servo valves in order to maintain the aim point.

Postfire. After firing is completed, the FCP prompts the operator to stow the LLM. When the stow button is pressed, the FCS issues the appropriate servo valve signals to, first, position the LLM to 310 mils (±8 mils) in elevation and, second, to 0 mils azimuth (±2.5 mils). This angle reference comes from the azimuth and elevation resolvers during stow, and it is backed up by the SRP. After it gets to the proper azimuth, the FCS lowers the LLM with commands to the elevation servo valve.

When the LLM reaches 35 mils (±5 mils), the FCS issues a hydraulic regulator and bypass command from the FCU to PDB connector J1, pin 54. This closes the PDB relay K1, supplying +24 V to the freewheel solenoid and +24 V to the elevation regulator solenoid on PDB J4 connector, pins 1 and 14. Return is by J4, pins 2 and 15. When the azimuth freewheel solenoid energizes, hydraulic pressure to the azimuth motor through the servo valve is removed, allowing the LLM to freewheel in azimuth as the LLM centering probe enters the centering socket. When the elevation pressure regulator solenoid energizes, hydraulic pressure to the elevation servo motor slows the rate of depression and reduces mechanical load on the cage ball screw actuators.

When the cage is fully down, a cage down switch on the probe completes a signal circuit to the FCS by PDB connector J1, pins 70 and 71, telling the FCS that the cage is down. The FCS releases the unlock command on PDB connector J1, pin 53, to the PDB K4 relay and supplies ±24 VDC to the transport latch actuator extend circuit engaging the transport latch. When

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the latch has fully engaged, a limit switch in the actuator opens, stopping actuator movement and sending a cage lock signal to the FCS by PDB connector J1, pin 73.

It is important to note that, during the stow sequence, as the actuator moves from the fully retracted position, the +24 VDC going to the LDS on relay K2 is lost. As the cage unlock signal is lost on PDB connector J3, pin N, a supplemental +24 VDC is provided by the LDS relay power command to K3 during stow at 12 mils (2 mils) to maintain LDS power until the FCS gets a cage down and lock indication from the transport lock actuator and the cage down switch on PDB connector J1; pins 70, 71, and 73. Once this signal sequence is received, the FCS removes the LDS relay power command, and the LDS contactor relay opens, stopping the motor. Finally, an LLM-stowed message is displayed on the fire control panel so the operator knows the LLM is stowed.

Reload. The functional sequence for reloading the LLM begins when the MLRS gunner selects a reload position. Initially, the FCS controls the LLM automatically, as described during the discussion of LLM FCS control (in this lesson and an earlier lesson). When the LLM has been positioned, the FCS enables the BC by supplying +24 VDC to the BC J1 connector, pins 21 and 15, from the FCU through PDB connectors J1 and J3. The +24 VDC circuit to pin 21 illuminates the enable lamp on the BC showing that the controller is enabled. Operators who want to move the LLM in azimuth or elevation press the appropriate switch: LLM Up, LLM Dn, LLM CW or LLM CCW. Once pressed, the switch sends a signal from the BC to the FCS by the PDB J3 and J1 connectors and the FCU J52 connector. The FCS issues an LDS on command along with the appropriate azimuth or elevation servo valve command, and the LLM moves. Once the LLM is at the desired position, the operator releases the switch and the FCS servo valve command is removed. The FCS maintains the LDS on command for 10 sec. If no further LLM commands come in from the BC in that time, the FCS removes the LDS on command. When reload is complete, the FCS operator presses the stow button on the fire control panel, and the FCS automatically stows the LLM as previously described. It also automatically disables the BC. All angle reference angles during reload come from the azimuth and elevation resolvers.

Troubleshooting and Repair of Drives

With the preceding information and TM 9-1425-646-30-1, you should be able to tell if the MLRS repairers you supervise can determine the exact symptom or malfunction properly as follows:

1. Find the symptom on the list.

2. Identify the malfunction number in the symptom index that most closely describes the fault in the system.

3. If the fault is displayed as a message on the FCP, compare description of conditions (given in parentheses) to actual condition of the equipment.

4. Perform troubleshooting procedures called for on the page given in the symptom index.

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To do their work, repairers you supervise use table 3-2, TM 9-1425-646-30-1; multimeters; breakout boxes; limit switch test cables; and DS/GS tool kits. Repairers can refer to electrical schematic diagrams and a hydraulic schematic diagram on unusual or extremely difficult fault isolation problems. These diagrams can also be used to reinforce the troubleshooting logic used in table 3-2. They are in appendix C, TM 9-1425-646-30-1, which is not necessary for completing this subcourse.

Use of Breakout Boxes

Depending on the malfunction symptom that is used for troubleshooting or the unusual or extremely difficult problems that require the use of schematics, the breakout boxes are extremely useful in helping to determine what you need to do to repair the malfunction. They were introduced in lesson 2.

MLRS breakout boxes (figure 4-1) connect cable assemblies and electronic LRUs to bring individual data lines to test points. Then voltages, resistances, and continuities can be measured. The multimeter, breakout boxes, and the limit switch test cable are used for electrical checks during launcher drive system troubleshooting.

Tools from the DS/GS tool kit are needed for moving the LLM manually and for accessing certain test points.

Figure 4-1. Breakout Box. This is the Power Distribution Box, the Largest Breakout Box.

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To use the breakout boxes, there are several things that must be done correctly or the breakout boxes will not be functional. The correct procedures for connecting the boxes follow:

1. Disconnect W1P2 from FCP J1 and W1P1 from FCP J2.

2. Connect W1P1 and W1P2 to keyed connectors on FCP breakout box.

3. Connect FCP breakout box keyed connectors to FCP J1 and J2.

4. Secure breakout box so you won't damage it.

5. Install power distribution box breakout box.

6. Disconnect W43P1, W75P1, W26P1, W76P1, W27P1, W23P1, W25P1, and W24P1 from the power distribution box.

7. Connect the eight connectors to keyed connectors on the PDB breakout boxes.

8. Connect the eight PDB breakout box connectors to keyed power distribution box connectors. Secure breakout box so it won't get damaged.

BOOM AND HOIST MECHANISM

This mechanism gives the MLRS the rapid reload capability that makes it a devastating weapon. Any malfunction in this system can cut the reload capability in half if only one side is affected, or disable the reload capability altogether, if both sides are affected. If the problem is mechanical, there is no way to load rocket pods, and the MLRS is useless. Even if the problem is electronic, the loading is slowed to the point that the MLRS is still useless. The MLRS repairers you supervise are responsible for isolating mechanical and electrical malfunctions in the system when the repairers are in the forward areas on direct support contact teams.

Boom Control

Description. Each LP/C bay is equipped with a boom and hoist mechanism. The left and right boom and hoist mechanisms are identical. The parts discussed in this lesson are: the boom motor, the control assembly, and the boom controller.

Boom Motor. A 2.5 hp, ±24 VDC electric motor drives the boom gear train, which extends and retracts the boom mechanism. The boom motor is controlled by the BC. It has a self-contained, mechanically applied, electrically released brake.

Control Assembly. This assembly contains the relays necessary to act on FCS commands for the switch position.

Boom Controller. This is a remote, manual switch box enabled by the FCS during reload with switches for selection of right, left, or both, and boom in or out. An enable light goes on when the controller is active.

Operation. Initial power distribution to the boom electrical system occurs when the MLRS system power switch on the fire control panel is turned on. When the EB K2 relay closes, +24 VDC from the battery box is routed by

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the J2 connector from the EB J6 connector, pin E, to the PDB positive bus bar. Pin A of the J5 and J7 PDB connectors is connected directly to the control assemblies' J2 connectors where +24 VDC is provided on pin A. Pin A is the +24 VDC for motor operation to control box relays K1 and K2. Pin E is the +24 VDC to the K3, K4, and K5 relays +24 VDC supplied at pin E is routed through the hoist up limit switch assembly to prevent boom movement if the hoist is not fully up.

Subsequent power distribution to move the booms in and out is determined by the switches on the BC. The operator may select right boom, left boom, or both by using a selector switch.

When the BC is enabled by the FCS, +24 VDC is provided to the BC by FCU connector J2 through the PDB on connectors J1 and J3. +24 VDC is routed to the BC by the J1 connector, pin 21. Pin 21 is supplied to the indicator lamp. Pin 15 is the power source (-15 VDC) for control switch signals.

The boom operator selects left, right, or both and uses the in or out switches to move the booms.

When the boom out switch is pressed, a signal is sent from the BC J1 connector, pin 14, to the FCU J2 connector, pin 14, by PDB connectors J3, pin A, and J1, pin 14. The FCU in turn sends a boom out command to the controller J2, B through the PDB (J1, pin 29 and J6, pin B) through the boom out limit switch. The out command provides a return to ground in the FCU. The connection of the controller J2, pin B, to ground completes controller relay circuits K1, K4, and K5, sending +24 VDC to the boom motor on J1, pin J (field). Return is by pin K. When relay K5 activates, the boom motor brake is released by J1 connector, pins N (+) and W (-). When the K1 relay activates, it also connects the armature S lead to return, determining the direction of rotation of the motor. The boom out limit switch is connected in series with the out command circuit to open and stop boom-out movement at the full-out position.

When the operator presses the boom-in switch, a signal is sent to the FCU J2 connector from the BC J1 connector, pin 1, through the PDB on J3, pin U and J1, pin 1. The signal causes the FCU to issue a boom-in command back to the PDB J5 and J7 connectors, pin D, via FCU J2 and PDB J1, pin 27. The boom-in command is received at the controller on J2 connector, pin D. The command causes activation of relays K2, K4, and K5. Relay K5 releases the electric brake and actuates K4. K4 actuates K2, and K2 routes +24 VDC to the motor by connector J1, pin J. K2 also connects the J1, pin T, to return (field) to determine direction of motor rotation. The FCU-provided in command is series connected with the boom-in limit switch. When the boom is fully in, the operator releases the boom-in switch.

Hoist Control

Description. The hoist assembly has a 2.5-hp motor and a motor brake. There is an electrical relay switching box for routing electrical power to the hoists for up or down movement. Two limit switches, an up and a down, are connected in series with the up and down commands from the FCU. They are mechanically activated to open the command circuits at the full up or full down positions of the hoist hooks.

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Operation. Initial power distribution to the hoist assemblies is essentially the same as that for the boom assemblies. +24 VDC to the hoist controller is routed from the EB through the PDB connector J2 to the PDB hoist output connectors J6 and J8. The +24 VDC at the controller J1 connector is received at pins A and E and supplied to the power side of the motor and the brake circuits and to the power side of relays K1, K2, K3 and K4 through time relays K5 and K6.

Subsequent power distribution is begun when the operator presses the hoist down or up switch on the BC. The selector switch on the BC also allows individual control of right hoist and left hoist or simultaneous control of both hoists.

When the operator presses the hoist down button, signal i goes from the BC on J1, pin 12, to the FCU BC interface on PDB J3, pin Y, and J1, pin 12, to the FCU J2 connector. The FCU interface issues a hoist down command to the hoist controller through the PDB on PDB J1, pins 25 or 77 or both, depending upon the hoist selection. The command is sent to the controller through PDB J6 and J8, pins D. The command is the creation of a return path for the K2, K4, K5, and K6 relays. The K5 and K6 relays provide +24 VDC to the K2 and K4 relays. The K2 relay provides +24 VDC to the hoist motor, and the K4 relay provides +24 VDC to the brake release coil. The hoist lowers until the operator releases the hoist down switch or until the mechanically actuated down limit switch is opened. The down limit switch prevents the operator from unwinding the entire cable from the hoist drum.

Hoist up operation is essentially the same sequence of operation except the hoist up return (command) actuates relays K1 and K3 rather than K2 and K4. The up limit switch protects the hoist motor by preventing its stalling at the full up position. A thermal protection device is installed in the motor power circuit to prevent the motor from overheating.

Troubleshooting and Repair of Mechanism

Procedures for troubleshooting and repairing the boom and hoist mechanism are found in the same manuals and require the same equipment as procedures for the elevation and azimuth mechanical drives. Look under troubleshooting and repair for those drives earlier in this lesson.

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REVIEW EXERCISES


1. What prevents damage to the cage centering probe during the last 35 mils of stow?

a. Azimuth freewheel solenoid.b. Elevation freewheel solenoid.c. Azimuth servo motor.d. Elevation servo motor

2. In figure 4-2, what is the malfunction number for “left boom will not retract”?

a. 43.b. 101.c. 77.d. 75.

Figure 4-2. Extract from TM 9-1425-646-30-1: Table 2-1. Symptom Index.

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3. Which limit switches are in the azimuth transducer?

a. 15, 27, and 73.b. 1.25, 15, and 106.c. 62.25, 73, and 196.d. 73, 106, and 196.

4. Which limit switch is mounted in the elevation actuator?

a. 1.25.b. 27.c. 62.25.d. 15.

5. The elevation and azimuth mechanical drives are part of which item?

a. Servomotor.b. Boom mechanism.c. Limit switch system.d. Launcher drive system.

6. By what signal from the FCS is the LDS contactor activated?

a. Boom control command.b. System start up command.c. LDS on command.d. SRP ready command.

Recheck your answers to the Review Exercises. When you are satisfied that you have answered every question to the best of your ability check your answers against the Exercise Solutions. If you missed two or more questions, you should retake the entire lesson, paying particular attention to the areas in which your answers were incorrect.

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Lesson 5

TROUBLESHOOTING AND REPAIRINGTHE FIRE CONTROL SYSTEM


Objective. When you have completed this lesson, you should be able to describe the proper troubleshooting and repair procedures for the fire control system.



POSITION DETERMINING SYSTEM

The position determining system (PDS) is one of the most important systems for entering fire data into the FCS. If this data is incorrect, it is possible to fire upon friendly troops. Repairers must be able to determine the malfunction in the PDS. To do this, they do the following.

Determine the exact symptom one of two ways. First, match the description of the fault with the malfunction number in TM 9-1425-646-30-1. Second, find the prompt in the symptom troubleshooting index (table 3-1, app B, TM 9-1425-646-30-1), if a prompt appears on the fire control panel. If a prompt does appear it will most likely be PDS data bad. (If it is not this prompt, look in the symptom index.) With the PDS data bad prompt, the following must be done.

Remove system power and disconnect left and right encoders from final drives. Leave W80P1 and W80P2 connected to the encoders. Perform start-up procedures outlined earlier in lesson 2. You can then use a multimeter or an oscilloscope.

Multimeter

When SRP ready light comes on, use a multimeter on the SRP test connector J3, pins 15 and 17 (+) and pin 2 ground for the left encoder and pins 16 and 18 (+) and pin 2 ground for the right encoder. Check each pin for a rise and fall of 3.5 VDC as each encoder is turned slowly by hand. Keep track of any failures or shortcomings.

If all voltages are good, inspect the encoder adapter and final drive tips to see if they are worn or damaged. Replace defective adapters. If adapter and drive tips are good, refer vehicle to the crew operator (13MS8) and tell the operator that the final drive may be defective.

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If only one voltage check fails, use incorrect voltages to check the continuity of the W80 (left) and W81 (right) cables to the encoder. If the cables are good, replace the encoder from the side that failed. Perform the voltage test to insure replaced encoder is good.

If all voltage checks fail, use a multimeter and check for ±5 VDC on W80P1 (left) and W80P2 (right), pins B (+) and F (-). If there is no voltage on one or both connectors, check for +5 VDC on SRP J2; pins 1 (+) and 15 (-), left side, and pins 7 (+) and 18 (-), right side.

If voltage is found on both sides, check continuity on the W80 and W81 cables (TM 9-1425-646-30, malfunction 29, steps 2 and 3). If no voltage is found on one or both sides, replace the W15 cable. If this does not solve the problem, then either the SRP/PDS or the FCU is bad. You then troubleshoot.

Oscilloscope

If an oscilloscope is available, you can do the following. (In this case, it is not necessary to disconnect the encoders, unless you find a fault in one or both of them.)

Perform system start-up procedures given in lesson 2. When you see the SRP ready light go on, connect a dual trace oscilloscope to pins 15 and 17 with respect to ground for the left encoder and pins 16 and 18 with respect to ground for the right encoder. A good encoder will display a 3.5-volt, peak-to-peak square wave.

CABLES

Thirty-five of the 45 cables in the MLRS are repairable at the GS level This eases the strain on the supply system because continuously providing replacements takes too much time and money. Repairers you supervise do the following:

1. Determine correct procedure from the cable index.

2. Using table 2-6, TM 9-1425-646-40 (not necessary for this subcourse), determine the procedure number to be used for the cable connector damaged. For example, the J1 connector on the W35 cable is damaged. Procedure 11 in table 2-6 shows it would be used to repair that particular connector and backshell. The P1 connector on the W35 cable is nonrepairable at the GS level. This cable will have to be turned in and reordered.

3. Cross reference the procedure number to the list at the beginning of paragraph 2-6 of the same TM to find the page number and, if necessary, the part number for that particular connector.

To repair the connector and/or backshell, loosen backshell or end bell and slide up cable. Tag wires as they are removed from connector by pin number or letter as appropriate. If backshell or end bell is damaged, remove connector and damaged component from cable. If just the connector is being replaced, keep all other parts on the cable.

After applying reference designation, install appropriate heat shrinkable tubing on cable using hot stamp kit. Solder tagged wires to appropriate pins in connector.

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Reassemble the connector and backshell or end bell and tighten all screws. Apply adhesive to shrink tubing, and using heat gun, shrink tubing in place.

To repair the connector by inserting new pins, first, disassemble connectors as in the procedure above. Then tag and desolder wires from damaged pins and remove damaged pins from connector. After applying reference designation, install appropriate heat shrinkable tubing on cable using hot stamp kit.

Crimp new pins to wires using crimping tool. Insert pins into appropriate place in connector using removal/insertion tool and reassemble connector and backshell. Apply adhesive to shrink tubing, then using heat gun, shrink tubing into place.

LINE REPLACEABLE UNITS

The FCS is made up of the electronic unit, fire control unit, fire control panel, stabilization reference package/position determining system, and interconnecting cables. It controls the launcher drive system that positions thelauncher With the necessary precision to make the MLRS an effective weapon system. Malfunctions in this portion of the MLRS can seriously detract from system effectiveness or even make it useless. 27M repairers are responsible for isolating malfunctions in the system in the forward areas. The following is what they do.

To determine the exact symptom or malfunction, identify the malfunction number which most closely describes the fault in the system. If the fault is displayed as a message on the fire control panel, match the description of conditions in parentheses to actual condition of the equipment. Then perform troubleshooting procedures listed in the symptom index by using table 3-2, TM 9-1425-646-30-1. You also need the following: multimeter, fire control panel breakout box, power distribution breakout box, limit switch test cable, and DS/GS tool kit.

AZIMUTH AND ELEVATION TRANSDUCERS

The azimuth and elevation transducers monitor cage position in mils. This information is transmitted to the fire control system through cables and is used whenever the cage is moved automatically. This information is essential for accurately aiming the missiles. The azimuth transducer also contains a limit switch deck that defines to the FCS the position limits of the cage. If a transducer fails, the fire control system does not know where the cage is aimed, and the MLRS is deadlined. 27M repairers troubleshoot, repair, and adjust the transducers in a shop. The following troubleshooting procedures are those repairers are most likely to do.

Elevation Transducer Assembly

Troubleshooting procedures for the elevation transducer assembly are limited to the resolver test. To do it, you need the following tools and test equipment: audio oscillator, 1311A-9701; an azimuth position transducer breakout box, 13101680; two digital voltmeters, 8050A-01; a dual trace oscilloscope, 212 (500 kHz); a synchro angle indicator (angle position indicator), SR202; a test cable, 13103717; and a tool kit, 13032302.

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The following procedures for the resolver test are taken from TM 9-1425-646-40. References cited are not necessary to complete this subcourse and have not been included.

The following instructions call for a 1311A-9701 audio oscillator as the power supply; however, you can use any power supply that can provide 11.7 to 11.9 VRMS, 1 W, 400 Hz. Monitor the power supply throughout the test and, if voltage goes out of tolerance, stop adjustments until power supply is brought back within tolerance.

If the assembly fails any part of this test or you see a distorted waveform, replace resolver/connector assembly.

To begin the resolver test, connect breakout box cable P1 to connector J1 on transducer. Connect breakout box cable J1 to the test cable, then the cable to the input terminals of angle position indicator (API). Connect wires as follows:

Connect these J1 wires to these terminals of the API.

Connect adapter cable from the 600-ohm terminal of the power supply to the breakout box power supply dual binding post. Connect digital voltmeter (DVM) test leads to the breakout box DVM dual binding post and set DVM for maximum AC voltage. Connect channel 2 of the oscilloscope to the breakout box test jack J1, pins 12 (RH-high) and 11 (RL-low). Connect channel 1 of oscilloscope to the breakout box test jack J1, pins 9 (R2-high) 13 (R4-low).

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Adjust API for

CONDITION POSITION

L-L VOLT 11.8MODE RSLVRTRK-FRZ TRACKBND WIDTH LOLOC-REM LOCAL

The following oscilloscope adjustments are for both channels, with one noted exception: trigger (not for channel 1), pos sig, 20V/DIV, 1MS/DIV, sweep-norm, and AC input.

Set the following power supply controls: frequency central for 400 Hz and voltage control for the minimum voltage. Turn on DVM, API, and power supply. Adjust power supply to 11.7 to 11.9 VAC as measured on DVM.

While watching the oscilloscope and the API, rotate input shaft on the transducer and compare waveforms on channels 1 and 2 of the oscilloscope. Note: Any time the waveforms are not correct in the following steps, replace resolver/connector.

Make sure the two signals are out of phase in the range of 0 to 180. If they are, disconnect channel 1 leads from breakout box test J1, pins 9 and 13, and connect channel 1 leads to breakout box test J1, pins 7 (R1-high) and 8 (R3-low). Rotate input shaft on transducer in opposite direction from rotation you did when comparing waveforms on channels 1 and 2. Does the API angle go from 180 to 90? Make sure the waveforms are out of phase in the range of 180 to 90. Note: Any time the waveforms are not correct in the following steps, replace resolver/connector.

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Rotate input shaft through 0 to 270, then to 180, and verify that the waveform is out of phase between 270 and 180. Leave input shaft at 180 as indicated on API. Disconnect oscilloscope from breakout box test jacks and turn it off.

Make sure the power supply voltage on DVM is between 11.7 and 11.9 VAC. Disconnect DVM leads from breakout box binding posts, and connect the leads so breakout box test jack J1, pins 7 (R1-high) and 8 (R3-low).

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While watching the voltage reading on the DVM, rotate input shaft from 180 to 270, then to 0, then to 90, and finally to near 180. Make sure the R1-R3 voltage is not higher than 12.3 V.

Connect DVM leads to breakout box test jack J1, pins 9 (R2-high) and 13 (R4-low). While watching DVM as before, rotate input shaft from 180 to 90 to 0 to 270 to near 180. Make sure the R2-R4 voltage is not higher than 12.3 V. Return input shaft to 0. Note: If voltage measurements are not correct in the following, replace resolver/connector.

This completes the resolver test. Turn off test equipment and disconnect breakout box cable P1 from transducer assembly. Disconnect adapter cable from power supply, the breakout box cable J1 from API, and the DVM test leads from breakout box.

Azimuth Transducer Assembly

Troubleshooting procedures for the azimuth transducer assembly include two tests, five adjustments, and two fault isolations:

Gear binding testResolver testRotary limit switch adjustmentSwitch deck A adjustmentSwitch deck B adjustmentSwitch deck C adjustmentMisoriented switch adjustmentFault isolation of binding gearFault isolation of resolver test

To troubleshoot and repair, repairers need the following:

An audio oscillator, 1311A-9701; an azimuth position transducer breakout box, 13103680; two digital voltmeters, 8050A-01; a dual trace oscilloscope, 212 (500 kHz); a synchro angle indicator (angle position indicator), SR 202; a test cable, 13103717; and a tool kit, 13032302.

Gear Binding Test. Make sure the input gear can be turned smoothly and freely by hand. If the gear binds, refer to fault isolation of binding gear towards the end of this lesson.

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MM4806, Lesson 5

Resolver Test

Note: This test calls for a 1311A-9701 oscillator as the power supply, but you can use any power supply that provides 11.7 to 11.9 VRMS, 1 W, 400 Hz. Monitor the power supply throughout the test and if the voltage goes out of tolerance, stop the adjustments until the power supply is within tolerance. If the assembly fails any part of this test or you see a distorted waveform, replace the resolver/connector.

To begin this test, connect breakout box cable P1 to connector J1 on transducer switch assembly, and connect cable P2 to connector J2. Connect breakout box cable J1 to the test cable, then connect the cable to the input terminals of the API.

Connect this wire to this terminal of the API.

Connect adapter cable from the 600-ohm terminal of the power supply to the breakout box power supply (P/S) dual binding post. Connect DVM test leads to the breakout box DVM dual binding post and set the DVM for maximum AC voltage.

Next, connect channel 2 of the oscilloscope to the breakout box test jacks J1, pins 12 (RH-high) and 11 (RL-low). Connect channel 1 of oscilloscope to the breakout box test jack J1, pins 9 (R2-high) and 13 (R4-low).

Adjust API in the order given for the following: 11.8 V, TRK, LO, LOCAL, and RSLVR.

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The following oscilloscope adjustments are for both channels, with one exception: trigger (except channel 1), pos signal, 20 V/DIV, 1 MS/DIV, sweep-normal, AC input.

Set the following power supply controls:

Frequency central for 400 Hz and voltage control for the minimum voltage. Turn on DVM, API, and power supply, and adjust power supply to between +11.7 and +11.9 VAC as measured on DVM. Then rotate input gear on transducer and compare waveforms on channels 1 and 2 of the oscilloscope. Make sure that the two signals are out of phase in the range of 0 to 180. Note: Any time waveforms are not correct, replace/resolver connector.

Disconnect channel 1 leads from breakout box test jack J1, pins 9 and 13, and connect them to breakout box test jack J1, pins 7 (R1-high) and 8 (R3-low). Rotate input gear on transducer in opposite direction from rotation when you compare waveforms on the channels. The API angle should go from 180 to 90. Compare waveform on channels 1 and 2.

Make sure the waveforms are out of phase in the range of 180 to 90. Rotate input gear through 0 to 270, then to 180, and make sure that the waveform is out of phase between 270 and 180 but is in phase at 180. Leave input gear at 180, as indicated on API.

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Disconnect oscilloscope from breakout box test jacks and turn it off. Check power supply voltage on DVM for +11.7 to +11.9 VAC then disconnect DVM leads from breakout box binding posts and connect them to breakout box test jack -- J1, pins 7 (R1-high) and 8 (R3-low). Note: Any time voltage measurements are not correct, refer to fault isolation of the resolver test at the end of this lesson. While observing voltage readings on the DVM, rotate input gear from 180 to 270. The voltage should not exceed 12.3 V.

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Connect DVM leads to breakout box test jack J1, pins 9 (R2-high) and 13 (R4-low). Note: Any time voltage measurements are not correct, refer to fault isolation of resolver test.

While observing voltage reading on DVM, rotate input gear from 180 to 90, then to 0, then to 270, then to near 180. The voltage should not be more than 12.3 V. Reconnect DVM to breakout box DVM dual binding post.

Rotate input gear until API reads 0. Use a pencil or chalk, and mark one tooth on the gear. Rotate input gear 360 (back to the mark) and make sure the API increases between 15.53 to 15.73. Return input gear to 0. Leave equipment connected for rotary limit switch adjustment.

Rotary Limit Switch Adjustment

CAUTION: The rotary limit switch has internal stops. Do not overtighten the adjusting screws because that might damage the switch. If you are not yet at the desired angle when you feel a marked increase in resistance, loosen lock screw on opposite side of deck and then complete adjustment. If you have to loosen the lock screw, go back to the other side of the deck and reset the adjustment on that side.

If the transducer-switch assembly passed the binding gear and resolver tests and the rotary limit switch cannot be adjusted, the switch/connector assembly is faulty.

Using No. 2 crosstip screwdriver and 10-mm socket, remove the six screws, two bolts, and eight washers that secure the cover. Remove cover and gasket. You can reuse the gasket if it isn't damaged. If it is damaged, replace it.

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The rotary limit switch has three decks, each with two actuation points (during 360 switch shaft rotation, the contacts of each deck alternately open and close twice). The following procedures adjust these points to actuation. If switch deck A cannot be adjusted within the proper limits in the following procedure, replace switch/connector assembly.

Switch Deck A Adjustment

After connecting test leads to DVM, turn on DVM and set controls for the 200-ohm range.

Connect DVM test leads to breakout box test jack J2, pins 12 and 13, and rotate input gear on transducer until API reads about 0. Verify that DVM is indicating open contacts.

Rotate input gear on transducer until you find point A2, where the switch is now actuating. Note: You have to find the existing switch actuation point so you'll know the switch starting point before you begin the adjustment.

Using a jeweler's screwdriver, loosen lockscrews B and H one turn. Then turn adjusting screw A, moving transducer input gear as required, until switch actuates at 59 as indicated on API. Tighten lockscrew H.

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Rotate transducer input gear until API indicates about 70. Rotate gear back and adjust screw A until the switch contacts open between 58.9 and 59.9 as indicated on API. Turning screw A clockwise moves the 59.4 line toward 90.

You may have to try several times to make the adjustment. If necessary, slightly tighten lockscrew B to complete the adjustment so you won't overshoot the actuating point.

The only allowable difference is between 59.4 and 61.4 for opening and closing of contacts.

Rotate transducer input gear until API indicates about 50. Rotate gear to increase angle to approach the 59.4 point again. Verify that, with the API angle increasing, the switch contacts close at no more than 61.4.

Readjust screw A as necessary to open switch contacts between 58.9 to 59.9 , and close the contacts at no more than 61.4. Tighten lockscrew B with a flat-tip screwdriver and rotate input gear on transducer back through 0 on API to find point A1 where switch is now actuating.

Using a flat-tip screwdriver, loosen lockscrew H and turn adjusting screw G, moving input gear as required, until switch actuates at about 300.

Rotate input gear back until API indicates about 290, then rotate the gear back towards 300 and adjust screw G until the switch contacts open between 300.1 and 301.1 (as indicated on the API). Turning screw G clockwise moves the 300.6 line toward 360.

Rotate input gear until API indicates about 310, then rotate gear back toward 300. Verify that the API angle decreases and switch contacts close at no less than 298.6.

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Readjust screw G as necessary to open switch contacts, between 300.1 and 301.1, and close contacts at least 298.6. Then tighten lockscrew H and recheck adjustment.

Switch Deck B Adjustment

If switch deck B cannot be adjusted within these limits, replace the switch/connector assembly.

Disconnect DVM test leads from breakout box test jack J2, pins 12 and 13, and connect them to test jack J2, pins 1 and 13. Rotate input gear on transducer until API reads about 0, then verify that DVM is indicating closed contacts. Rotate input gear on transducer until point B2 is found where the switch is now actuating.

You have to find the existing switch actuation point so you will know the switch starting point before you begin the adjustment.

Using a flat-tip screwdriver, loosen lockscrews D and J one turn. Then turn adjusting screw I, moving transducer input gear as required, until the switch actuates at about 86 (as indicated on API). Tighten lockscrew D.

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Rotate transducer input gear until API indicates about 75. Rotate gear back toward the actuating point and adjust screw I until the switch contacts open, between 85.7 and 86.7 (as indicated on API).

You may have to try several times to make the adjustment. If necessary, tighten lockscrew J slightly so you will not overshoot the actuating point.

Rotate transducer input gear until API indicates about 95. Rotate gear back and verify that, with the API angle decreasing, the switch contacts close at no less than 84.2. You can expect a difference from between 86.2 and 84.2 for opening and closing of contacts.

Readjust screw I as necessary to open switch contacts, between 85.7 and 86.7, and close the contacts at least 84.2. Using flat-tip screwdriver, tighten lockscrew J. Rotate input gear on transducer back through 0 on the API to find point B1, where switch is now actuating. Loosen lockscrew D and turn adjusting screw C, moving input gear as required, until the switch actuates at about 274.

Rotate the input gear back until API indicates about 285. Rotate the gear toward 274 and adjust screw C until the switch contacts open between 273.3 and 274.3 (as indicated on the API). Turning screw C clockwise moves the 273.8 line toward 360.

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Next, rotate input gear until API indicates about 265, then rotate gear back toward 274. Make sure the API angle increases and the switch contacts close at no more than 275.8. Readjust screw C as necessary to open switch contacts, between 273.3 and 274.3, and close switch contacts at no more than 275.8. Tighten lockscrew D and recheck adjustment.

Switch Deck C Adjustment

If switch deck C cannot be adjusted within the proper limits, replace the switch/connector assembly.

Disconnect DVM test leads from breakout box test jack J2, pins 1 and 13, and connect them to test jack J2, pins 1 and 2. Rotate the input gear on transducer until the API reads about 0. Make sure the DVM indicates closed contacts. Now, rotate input gear on transducer until you find point C2, where the switch is now actuating. Note: You have to find the existing switch actuation point so you'll know the switch starting point before you begin the adjustment.

Using a flat-tip screwdriver, loosen lockscrews F and L one turn, then turn adjusting screw K, moving transducer input gear as required, until the switch actuates at about 158 as indicated on API. Tighten lockscrew F.

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Rotate transducer input gear until API indicates about 148, then rotate gear back towards the actuating point, and adjust screw K until the contacts open between 158.2 and 159.2 (as indicated on the API).

You may have to make several tries for this adjustment. If necessary, tighten lockscrew L slightly to complete the adjustment without overshooting the actuating point.

Rotate transducer input gear until API indicates about 167. Rotate gear back and verify that, with the API angle decreasing, the switch contacts close at a minimum of 156.7. You can expect a difference of between 158.7 and 156.7 for opening and closing contacts with this switch.

Readjust screw K as necessary to open switch contacts, between 158.2 and 159.2, and to close the contacts at no less than 156.7. Tighten lockscrew L, then rotate input gear on transducer back through 0 on the API to find point C1, where switch is now actuating.

Loosen lockscrew F, and turn adjusting screw E, moving input gear as required, until switch actuates at about 200.

Rotate input gear until the API indicates about 211. Rotate gear toward 200, and turn adjusting screw E until the switch contacts open, between 200.8 and 201.8 (as indicated on the API). Turning screw E clockwise moves the 201.3 line toward 270.

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Rotate input gear until the API indicates 190, then turn gear back towards 201. Verify that the API angle increases and the switch contacts close at a maximum of 203.3. Readjust screw E as necessary to open switch contacts, between 200.8 and 201.8, and close switch contacts at a maximum of 203.3. Tightening lockscrew F and rechecking adjustment completes the adjustment of the rotary limit switch.

Turn off test equipment and disconnect breakout box cables from connectors J1 and J2 of transducer switch. Disconnect the test leads from DVM and breakout box, adapter cable No. 3 from power supply, and breakout box cable J1 from API.

Position gasket and cover on transducer-switch housing. Then, using a No. 2 crosstip screwdriver and a 10-mm socket, install the six screws, two bolts, and eight washers. Torque screws and bolts between 0.5 to 0.8 N.m. (newton meter).

Tag assembly as ready for issue if test and adjustment was successfully completed.

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Misoriented Switch Adjustment

Note: If any switch deck cannot be adjusted to proper limits, replace the switch/connector assembly.

This procedure establishes the switch closure angle required to adjust the rotary limit switch. The procedure that follows covers adjusting the switch closure angle for deck A. All other decks are done the same way. (The values for decks B and C are in parentheses.)

Rotate the transducer-switch input gear to point A2, where the switch actuates. Note the angle on the API. It should be about 59 (86 for B2 and 159 for C2).

Rotate input gear so that the API angle goes through 0 until you find point A1, establishing the other limit of the switch closure. It should be approximately 300 (274 for B1, 201 for C1).

Using a jeweler's screwdriver, loosen lockscrews H and B for deck A (D and J for deck B, F and L for deck C). Turn adjusting screw A for deck A (C for deck B, E for deck C) and move gear so that point A2 moves to the position shown.

Rotate the input gear until you find point A1 again. (It should have moved to a new position.) Return to point A2. Continue adjusting screw A and rotating gear until A2 is approximately in the position shown. Point A1 will also move to a new position.

Using a flat-tip screwdriver, tighten lockscrews B and H for deck A (D and J for deck B, F and L for deck C).

With this tightening, you've finished the adjustment of a misoriented switch. You can now make a complete adjustment of the appropriate switch deck.

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Fault Isolation of Binding Gear

Using a crosstip screwdriver, remove the six screws and washers securing the front cover. Remove cover and gasket, and inspect all gears for proper mesh. Then inspect split gears for broken or disconnected springs.

Using 7/64-inch socket head key, loosen the clamp screw on gear B. Spin gear E and check for evidence of gear binding. If it binds, retighten clamp screw on gear B and examine gears A and F for broken teeth. Replace any defective gear. If gears are not defective, loosen clamp screw in gear A and spin-gear E. If there is no binding, replace bearings for gears A and B. If there is still binding, replace bearing for gears E and F. If there was no binding when you spun gear E, inspect gears B, C, and D for broken teeth. Replace any defective gears.

If gears are not defective, retighten clamp screw on gear B and loosen clamp screw on gear D, then spin gear E. If it does not bind, replace the bearings for gear D. If it binds, replace the bearings for gear C.

Use methyl-ethyl-ketone to clean sealing compound from the cover gasket. Install cover and gasket and secure with the six screws and washers. Using crosstip screwdriver, tighten screws.

Fault Isolation of Resolver Test

First, turn off power source. Then using the DVM, measure the resistance between J1, pins 12 and 11. Resistance should be between 60 and 82 ohms. If resistance is not correct, replace resolver/connector.

Next, using DVM, measure the resistance between J1, pins 7, 8, 9, and 13. Resistance should be between 176 and 238 ohms. If resistance is not correct, replace resolver/connector. If resolver passes both the resistance checks, a slipping gear may be the fault, and you go on.

Using a crosstip screwdriver, remove the six screws and washers that hold on the front cover. Remove front cover and gasket. Spin gear E and verify that all gears are turning. If they are, hold gear E and try to turn gear C. If gear C turns, go on to the next. Hold each gear until you find the loose clamp screw. If gear C does NOT turn, check clamp screws securing the coupling between the resolver and the gears.

If you find a loose clamp screw, remove and clean it. Then, apply sealing compound, reinstall, and tighten the clamp screw. Use methyl-ethyl-ketone to clean the sealing compound off the cover gasket. Install gasket and front cover and secure them with the six screws and washers. Use a crosstip screwdriver to tighten the screws.

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REVIEW EXERCISES


1. How many Hz must the power supply be set at to test the elevation or azimuth transducers?

a. 400.b. 300.c. 600.d. 200.

2. What is the range of voltage the power supply must be set at in order to test the transducers?

a. 10.6 to 10.8.b. 11.3 to 11.5.c. 10.9 to 11.1.d. 11.7 to 11.9.

3. The DVM reads 11.8 V. While rotating the input shaft on the elevation transducer, you should check to insure that the R1-R3 voltage does not exceed how many V?

a. 12.5.b. 12.3.c. 10.9.d. 11.1.

4. You are adjusting set screw A. What is the greatest number of degrees the switch contacts can be open during adjustment of switch deck A?

a. 54.9 to 55.9.b. 300.1 to 301.1.c. 298.6 to 299.6.d. 58.9 to 59.9.

5. Which gears of the azimuth transducer should you inspect for broken teeth?

a. A and Rb. B and C.c. E and D.d. A and B.

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6. You are performing fault isolation of the AZ transducer. The resolver has passed the resistance check. Which is the faulty component?

a. Resolver.b. Slipping gear.c. Switch deck.d. Connector.


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Lesson 6

MAINTENANCE OF THE MLRS CARRIER, M993


Objectives. When you have completed this lesson, you should be able to identify major components and describe M993 start-up procedures and organizational checks.


Standard. You must score at least 70 on the end-of-course examination that covers this lesson and lessons 1, 2, 3, 4, 5, and 7.

SIMPLIFIED TEST EQUIPMENT/INTERNAL COMBUSTION ENGINE

The MLRS carrier, M993, uses the simplified test equipment/internal combustion engine (STE/ICE) maintenance system at organizational level. This system tests and isolates malfunctions of all major systems and includes electrical circuits, ignition components, and engine performance. Preventive maintenance and most servicing is done by the vehicle crew. Organizational maintenance is by replacement of minor components, and direct support is by replacement of major components. General support soldiers return unserviceable components to stock and piecepart repair major items where direct support is limited by tools, equipment, or training.

The suspension and power pack components of the carrier are interchangeable with the IFV/CFV. A NATO standard “slave” interconnect receptacle allows transfer to or from any other multibattery source. This means simpler logistics and fewer maintenance training requirements.

Maintenance Duties

Crew maintenance is done by the 13M (MLRS Crewmember) and 15D (Lance Crewmembers/MLRS Sergeant). Organizational maintenance is the responsibility of the 63T (Bradley Fighting Vehicle System Mechanic) assigned to battalion maintenance, while 63G (Fuel and Electrical Systems Repairer) and 63H (Track Vehicle Repairer) have carrier repair responsibilities at direct and general support.

Maintainability

The MLRS carrier has excellent component accessibility that significantly shortens maintenance time. All inspections may be completed without tools. The tilt-cab, large engine compartment doors, and grouping of daily service items all contribute to easy servicing. More extensive maintenance is done with

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the cab tilted forward (engine controls are mounted on a pedestal and do not tilt with the cab). The carrier has a reliability rating of 800 mean kilometers between mission failure (MKBMF).

MECHANICS OF THE SUSPENSION SYSTEM

The MLRS carrier suspension is a lengthened version of the infantry fighting vehicle/combat fighting vehicle (IFV/CFV) suspension. Each side has six dual roadwheels, a front sprocket, a raised rear idler, four support rollers, and a high-return track.

The track is single-pin with forged steel blocks, rubber bushings, and detachable rubber pads. Track tension is adjusted by a grease-filled cylinder mounted between the hull and idler.

The springs are high-strength steel torsion bars splined to trailing roadarms. They form an independent suspension system. Linear hydraulic shock absorbers are attached to numbers 1, 2, and 6 roadarms to stabilize the carrier during rough terrain operation.

There is a lockout system mounted concentrically with the torsion bars at roadwheels 1, 5, and 6. It is a hydraulically actuated, multidisc brake that provides sufficient stabilization for the vehicle during reloads and fire missions. The lockout system is engaged and disengaged by a hand pump on the driver's control panel. An interlock prevents the driver from accidentally placing the vehicle in gear without disengaging lockout system. Lockout units can be installed at all torsion bar stations if additional stability is required.

The MLRS carrier power train is interchangeable with the IFV/CFV. It is a 500-hp Cummins diesel engine coupled to a General Electric crossdrive transmission. The power train can be installed complete with cooling and hydraulic systems intact.

The tilt-cab makes it easy to remove the power pack. Controls and wiring are routed through the hinge point, allowing the cab to be tilted without having to disconnect wires or controls.

CIRCUITRY

The independent carrier circuit includes a bank of four vehicle batteries, a vehicle alternator, and a receptacle for external recharge. The carrier circuit is activated by a vehicle master switch and provides power to carry vehicle load requirements. Tied into the launcher circuit, it provides power along with launcher batteries and recharges the launcher batteries themselves.

Carrier power is hooked into launcher circuitry through a relay assembly controlled by a launcher interconnect switch. The circuit is protected on the carrier side of the launcher interconnect switch by a 400-amp fuze.

The carrier batteries and the relay assembly connecting the carrier power with launcher power are located on the left side of the engine compartment. A door in the engine compartment provides access to the batteries and relay assembly. The relay assembly, located forward of the four batteries, also contains the 400-amp fuze.

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DRIVER'S CONTROLS AND INDICATORS FAMILIARIZATION

Before you read the preventive maintenance checks and services, you need to familiarize yourself with the driver's controls and indicators. The following extracts (figures 6-1 and 6-2) are from TM 9-1450-646-10.

Figure 6-1. Extract from TM 9-1450-646-10 Showing an Overall View of the Driver's Area.

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Figure 6-2. Extract from TM 9-1450-646-10 Showing Details of All the Panels in the Drivers Area.

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Figure 6-2. Extract from TM 9-1450-646-10 Showing Details of All the Panels in the Driver's Area--continued.

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Figure 6-2. Extract from TM 9-1450-646-10 Showing Details of All the Panels in the Driver’s Area—continued.

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Figure 6-2. Extract from TM 9-1450-646-10 Showing Details of All the Panels in the Driver's Area—continued.

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Figure 6-2. Extract from TM 9-1450-646-10 Showing Details of All the Panels in the Driver’s Area—continued.

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Figure 6-2. Extract from TM 9-1450-646-10 Showing Details of All the Panels in the Driver's Area--continued

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Figure 6-2. Extract from TM 9- 1450-646-10 Showing Details of All the Panels in the Driver’s Area--continued

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Figure 6-2. Extract from TM 9-1450-646-10 Showing Details of All the Panels in the Driver’s Area--continued

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Figure 6-2. Extract from TM 9-1450-646-10 Showing Details of All the Panels in the Driver’s Area--continued.

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Figure 6-2. Extract from TM 9-1450-646-10 Showing Details of All the Panels in the Driver's Area--continued

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Figure 6-2. Extract from TM 91450-646-10 Showing Details of All the Panels in the Driver's Area--continued

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PREVENTIVE MAINTENANCE CHECKS AND SERVICES

Now you are ready to supervise PMCS on the carrier. See the extract from TM 9-1450-646-10 below.

Figure 6-3. Extract from TM 9-1450-646-10: Preventive Maintenance Checks and Services.

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Figure 6-3. Extract from TM 9-1450-646-10: Preventive Maintenance Checks and Services--continued.

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Figure 6-3. Extract from TM 9-1450-646-10: Preventive Maintenance Checks and Services--continued

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Figure 6-3. Extract from TM 9-1450-646.10: Preventive Maintenance Checks and Services--continued

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REVIEW EXERCISES


1. You are performing PMCS on the ventilation system. What is the first step?

a. Check that the vent filtration handle will engage in firing position.b. Check that air flows from ducts when fan control switch is in LO, MED, and HI positions.c. Move vent fan control override switch to on.d. Move vent filtration handle to normal position.

2. While performing PMCS on the NBC system you notice that there is no warm air coming out of the commander's, gunner's, and driver's air outlet hoses. What item number from the procedures is used to check this problem?

a. 44.b. 48.c. 42.d. 41.

3. Which road wheels of the carrier contain the linear hydraulic shock absorbers?

a. 1, 3, and 5.b. 1, 2, and 6.c. 1, 5, and 6.d. 1, 3, and 6.

4. Which road wheels of the carrier contain the suspension lockout?

a. 1, 2, and 6.b. 1, 3, and 5.c. 1, 3, and 6.d. 1, 5, and 6.

5. What amperage is the fuze that protects the carrier circuitry?

a. 100 amps.b. 300 amps.c. 400 amps.d. 200 amps.


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LESSON 7

THE DEEP ATTACK MISSILE SYSTEM:MAJOR COMPONENTS, SUPPORTING EQUIPMENT,

AND TESTING

Task. There is currently no soldier's manual task related to this lesson.

Objective. When you have completed this lesson, you should be able to describe the major components, the supporting equipment, and the testing procedures of the Deep Attack Missile System.


Standard. You must score at least 70 on the end-of-subcourse examination that covers this lesson and lessons 1 through 6.

MAJOR COMPONENTS

The Deep Attack Missile System is designed to defeat the deep threat. The deep threat pertains to enemy positions outside the range of MLRS rockets and other tube artillery. The increased range of the Deep Attack Missile System is achieved by using Army Tactical Missile System (ATACMS) missiles integrated with the launch and ground support equipment of the MLRS.

The major components of the Deep Attack Missile System consist of two ATACMS missiles with missile launch pod/containers (MLP/Cs); an M270 launcher; and a command, control, and communications (C 3) system. (See figure 7-1.) The C3 system is described in Lesson 1.

Missile and Missile Launch Pod/Container

The ATACMS missile (figure 7-2) is a tube-launched semi-ballistic missile. It is a certified round propelled by a solid-propellant rocket motor, inertially guided, and launched from the M270 launcher. It is aimed and launched, then internally guided to the target. The missile is factory-assembled, checked out, and packaged into its storage and firing container, an MLP/C. The combined missile and MLP/C is called a missile/launch pod assembly (M/LPA). The M/LPA is placed into the ammunition inventory as a single unit, ready to be stored or issued for firing.

M270 Launcher

The Deep Attack Missile System M270 launcher retains its capability to launch the existing MLRS family of munitions, thus providing dual launch capability in MLRS battalions. The components of the Deep Attack Missile System M270

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Figure 7-1. Deep Attack Missile System.

Figure 7-2. ATACMS Missile and Missile Launch Pod/Container.

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launcher that will be covered in this lesson are the payload interface module (PIM), the electronics unit (EU), the program load unit (PLU), the electronics box (EB), and the power distribution box (PDB) (figure 7-3).

Payload Interface Module. The PIM is located forward of the FCU/SRP compartment between the two M/LPAs. The PIM serves as an interface between the EU, the FCU, the SRP, and the on-board weapons for the purpose of power switching and data communications. The PIM contains four circuit card assemblies (CCAs): a controller/memory/peripheral interface CCA, two switchable input/output (I/O) CCAs, and a power supply CCA.

Controller/Memory/Peripheral Interface CCA. The controller/memory/peripheral interface CCA is the central processing unit (CPU) CCA. It consists of an eight-bit microprocessor, a memory section, a serial input/output (SIO) port, a counter time circuit (CTC) baud rate generator, and four eight-bit parallel input/output (PIO) ports.

Figure 7-3. Major Components of the M270 Launcher.

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The CPU performs all of the general-purpose controlling I/O functions for the PIM. It also has direct access and control of all system resources (memory and I/O devices) through the system bus.

The memory section consists of 8 K words of electrically erasable, programmable, read-only memory (EEPROM) and 96 K words of static random access memory (RAM). The PIM's resident program resides in the EEPROM. It performs such functions as the power-on sequencing, the built-in-test (BIT), and the hardware initialization, and it supports data communications with the EU. During the PIM's power-on sequence, the resident program is transferred from EEPROM to RAM. A BIT function and a hardware initialization are performed on the PIM. Once initialized, the PIM's resident program establishes communications with the EU and loads the PIM's operational program from the EU into RAM. The operational program allows the PIM to control power switching and data communications between the FCS and the weapons. It also allows reprogramming of the EEPROM's resident program through the EU.

The SIO port consists of a three-wire RS-232 data link that provides the signal interface between the EU and the PIM.

The CTC baud rate generator sets the rate of data transfer between the CPU and the EU. The baud rate is variable and under software control from the CPU. The baud rates available are 150, 300, 600, 1,200, 2,400, 4,800, 9,600, and 19,200 bits per second (bps). The nominal operating baud rate is 19,200 bps.

The four PIO ports interface with the automatic test equipment (ATE), the bite register, the control register and the internal status register of the PIM.

Input/Output CCAs. The two identical I/O CCAs form what is called the input/output section. Each I/O CCA is capable of providing up to six power circuits and six communication channels to each M/LPA.

The weapon power select circuitry is capable of providing +24 VDC at 4 amps to a maximum of 12 weapons simultaneously The routing of power is under software control, and built-in test equipment (BITE) circuitry is provided to detect the presence of power on each line. Overcurrent protection is also provided, and power is removed from the weapons in the event of an overcurrent condition.

The weapon data select circuitry consists of 12 three-wire RS-423 serial communication channels (SCCs) (6 for each CCA). The RS-423 SCCs establish a data link between each weapon and the on-board FCS through the PIM's CPU. The rate of data transfer between the CPU and the weapons is variable and under software control. The baud rates available are 150, 300, 600, 1,200, 2,400, 4,800, 9,600 and 19,200 bps. The nominal operating baud rate is 19,200 bps.

Power Supply CCA. The power supply CCA provides the three voltages that are necessary to operate the PIM. With appropriate input power (+24 VDC) applied, the power supply CCA provides +12 VDC, -12 VDC, and +5 VDC to the PIM's circuits. Internal operation of the PIM is rated at 4 amps, with an additional 48 amps available for distribution to the warheads.

Electronics Unit. The EU is bolted to the forward end of the carrier bed, below the cage assembly. It provides complete software control of the FCS. The EU stores, processes, displays, and acts upon data entered by the operator using the fire control panel (FCP) or through the launcher's digital data communications link. During a firing sequence, these data are combined with data from

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the stabilization reference package/position determining system (SRP/PDS) and the launcher's positioning transducers to provide the firing azimuth and elevation angles of the launcher. During reloading operations, the EU controls the movement of the launcher and the boom and hoist assemblies at the request of the boom controller (BC) operator.

The EU consists of a main processor, two auxiliary processors, memory, a systems bus, I/O interfaces, and a power supply.

The main processor (CPU A) is a 16-bit CPU that is capable of performing all of the general-purpose computational and I/O tasks for the FCS. A main processor local bus provides interface to a 12-bit peripheral data bus and two SIO ports. The main processor also controls the two auxiliary processors.

CPU A contains local memory that it can access directly. The local memory consists of 24 K words of static RAM and 8 K words of EEPROM. The EEPROM provides nonvolatile storage for two bootstrap programs. These two programs, generic bootstrap and applications bootstrap, are used to initialize the EU during the FCS power-on sequence. During EU initialization, the bootstrap programs perform CHECKSUM tests on the EEPROM and a READ/WRITE test on the main processor RAM. They also control and initialize reprogramming functions of the EEPROM and the system's bulk storage memory unit (BSMU).

The two auxiliary processors perform computational tasks. Each auxiliary processor contains 32 K words of local RAM. During fire mission processing the main processor downloads special-application software (for the on-board weapon type) into the local memory of both auxiliary processors. Each auxiliary processor then computes a ballistic solution for the mission in progress. The results of each auxiliary processor are then returned to the main processor, where a final ballistic solution is computed by interpolating the results obtained by the two auxiliary processors.

The memory section consists of three CCAs containing both system memory and bulk storage memory (BSM). The memory section is accessible by the main processor and the auxiliary processors. The main processor has priority over the auxiliary processors.

The system memory contains 512 K words of system operating RAM. It has an error detection and correction circuit that is capable of detecting any single- or double-bit errors within a word. This circuit also has the capability to correct any single-bit errors. The BSM contains a total of 1,024 K words of memory of which 256 K words are partitioned for data memory and 768 K for program memory.

The BSM data memory (database) is capable of storing the last start-up data (system, PDS, and communications), three fire missions (one dedicated to a priority mission), five free text messages, on set of meteorological (MET) data, three target-area low-level METs (METTAs), and one firing-point low-level MET (METFP). It can also store three of each type of grid point coordinates (reload, firing, rendezvous, move, hide, and survey), the last 10 communications processor (CMP) overhead messages, and 100 malfunction prompts or malfunction codes.

The BSM program memory provides storage for both common-application software and the various types of special-application software. The common-

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application software allows the FCS to perform all launcher functions except computing ballistic solutions and communicating with the munitions. These two functions are performed by the special-application software.

During the FCS power-on sequence, the bootstrap program (in the EEPROM of the main processor) initiates the DOWNLOAD BSM function. This function downloads both common-applications and special-applications software for the on-board weapon type from the BSM to the system operating RAM.

The BSM is reprogrammable through the use of a PLU. If the bootstrap program detects the presence of a PLU during the FCS power-on sequence, the DOWNLOAD BSM function downloads all application program files from the PLU and programs them into the BSM.

Program Load Unit. The PLU is used to load the various types of software programs into the EU. The PLU consists of the basic carrier; a removable cassette; and cable assemblies W21, W22, and W52 (figure 7-4). The PLU is stored

Figure 7-4. Program Load Unit.

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in the PLU storage container. The storage container holds a basic carrier with cassette, two spare cassettes, and the three cable assemblies.

Input power to the PLU is provided by the M270 launcher in the form of +24 VDC to +28 VDC. Input power requirements of the PLU are +18 VDC to +32 VDC.

Basic Carrier. The basic carrier accepts a programmable removable cassette and transfers the data on the cassette into the system operating RAM of the EU. The data in RAM are then written into the BSM. This process is performed automatically when the PLU is connected to the FCS and the SYS PWR switch on the FCP is turned ON. It is also performed at the request of the operator through the FCS PLU READ menu routine.

The front panel of the carrier consists of two connectors, four lamps, and a grounding connector. Connector X1 is the input power connector to the basic carrier. Connector X2 interfaces the PLU with the EU (through the PIM) for transferring digital data. The four indicator lamps, 24V, BER, DUE, and FEHL, show the status of the PLU.

The 24V lamp, when lit, indicates that the supply voltage of +18 VDC to +32 VDC is available to the PLU.

BER is an abbreviation of the German word for ready. When lit, this lamp indicates that the PLU is ready for use. When the BER lamp illuminates, a signal is sent from the PLU to the EU indicating that the PLU is ready. The EU then returns a signal to the PLU that tells the PLU to begin sending data. If the cassette is not fully locked into place, the BER indicator lamp will not illuminate. The BER lamp may blink while the carrier warms up when the temperature is below 40 F, or if there is a gap in the transmission of data. Otherwise, a continuous blinking condition indicates a failure.

DUE is an abbreviation of the German word for transfer. When lit, this lamp indicates that data are being transferred to or from the basic carrier. If the lamp does not illuminate, it could indicate a failure within the EU or the PLU.

FEHL is an abbreviation of the German word for fail. When lit, this lamp indicates a failure within the PLU.

Removable Cassette. The programmable data cassette is capable of storing the various types of software applications that are available for use by the EU. It can store up to 1,024 K words of information in its bubble memory. The cassette mates with a connector on the carrier and is locked into place with a locking lever. The cassette contains a write-protect screw that should be screwed in at all times. When the write-protect screw is screwed out, data may be written to the cassette.

Cable Assemblies. Cable assembly W21 interfaces the PLU with the M270 launcher's FCS. It provides power to the PLU and allows for the transmission of data between the PLU and the EU through the PIM. W21P1 connects to W31P2, which is located behind the curbside umbilical cable door. W21P2 connects to X2 and W21P3 connects to X1 on the basic carrier.

Cable assemblies W22 and W52 are used for programming the EU directly at EU connector J8. W52 provides primary power to the PLU directly from the EB at connector J9, and W22 provides the digital interface between the PLU and the EU at connectors J8 and J9.

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Electronics Box. The EB is mounted at the end of the battery box. It serves to distribute prime power from the battery box to various launcher components.

The EB contains connectors, relays, diodes, terminal boards, bus bars, filters, and circuit breakers (figure 7-5). Its three relays are used to distribute prime power from the battery box to the launcher.

Power inputs to the EB are provided by connectors J7 and J8 from the battery box and J3 from the carrier batteries. Power outputs from the four launcher drive system (LDS) batteries are provided by the EB through J5 to the LDS contactor assembly and through J6 to the power bus bars in the PDB. Outputs from the two FCS batteries are provided by the EB through J1 to the EU, J2 to the CMP, J4 to the FCU, and J11 to the PIM. Connector J9 serves as a test connector during automatic testing of the EB and also connects the PDB to the EB through cable assembly W58 during normal launcher operation. Connectors J12, J13, J14, and J15 serve as auxiliary power connectors. J16 interfaces with the launcher-dedicated alternator.

Relay K1 is a 250-amp relay used to distribute prime power from the two FCS batteries to the FCS components (the EU, the FCU, the CMP, and the PIM).

Relay K2 is a 400-amp relay used to distribute prime power from the four LDS batteries to the LDS contactor assembly and to the power bus bar in the PDB.

Relay K3 is a 50-amp relay used to dedicate the launcher alternator strictly to the two FCS batteries while the LDS is operating. This is to ensure that the FCS can provide the required external power to the smart munitions prior to

Figure 7-5. Electronics Box.

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launch. When the LDS is not operating, relay K3 connects the launcher alternator in parallel with the carrier alternator to charge all on-board batteries.

Power Distribution Box. The PDB is located at the rear of the launcher. It serves as the main distribution point for electrical power and command signals to various launcher subsystems.

The PDB contains 1 filter board assembly with 10 diodes, 2 resistors, 22 filters, and 5 relays. (See figure 7-6.) The PDB also contains a positive and a negative bus bar.

Input power to the PDB is through connector J2 from the EB. Direct power output is through J5, J6, J7, and J8 to the boom and hoist systems.

Relay K1 is used during the stow operation of the rocket launcher. It is energized at 35 mils in elevation and provides +24 VDC to the azimuth freewheel and stow pressure solenoids. Relay K1 is energized by the HYDR REGLTR & BYPASS command.

Relay K2 provides +24 VDC to relays K1 and K2 in the LDS contactor, thus energizing the contactor. Relay K2 is energized by the LDS ON command.

Relay K3 is also used during the stow operation of the rocket launcher. It is energized at 35 mils in elevation and provides +24 VDC to the LDS power relay (K2). Relay K3 provides actuation voltage to relay K2 as the travel hooks ex-

Figure 7-6. Power Distribution Box.

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tend, removing the +24 VDC CAGE UNLOCK signal. Relay K3 is energized by the LDS RELAY PWR command.

Relay K4 provides +24 VDC to the travel lock actuator, allowing the hooks to extend and retract. It is energized by the CAGE UNLOCK command.

Relay K5 is a 100ms time delay relay, with its contacts connected in series by the LDS CONTACTOR HI command. Relay K5 serves to ensure that relay K3 in the EB is deenergized prior to the energizing of the LDS. Relay K5 is energized by relay K2.

SUPPORTING EQUIPMENT

Trainer Missile/Launch Pod Assembly

The trainer M/LPA provides training simulation for M/LPA and LP/C loading, handling, and firing. It provides simulation of rocket and missile failures and checks the electrical interface between the trainer M/LPA and the M270 launcher. The major components of the trainer M/LPA are the LP/C structure, the simulator assembly and the interface cables (figure 7-7).

Figure 7-7. Major Components of the Trainer M/LPA.

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LP/C Structure. The trainer M/LPA structure has the external appearance of the tactical LP/C. The trainer's EB is secured to slide mounts in the aft end of rocket tube number four. The bushings on the bottom of the trainer M/LPA are strengthened to minimize wear from repeated loading and unloading operations.

Simulator Assembly. The simulator assembly contains electronic circuits to simulate weapon types, to simulate failure modes, and to check the electrical interface between the trainer M/LPA and the M270 launcher. It contains one CCA, a trainer harness assembly, two cable connectors, and four front-panel switches (figure 7-8).

Weapon Select Switches. As many as 63 weapon identification codes can be selected using WEAPON switches S3 and S4 on the simulator assembly front panel. Switches S3 and S4 connect the rocket status (RSTAT) lines with the return (RTN) line to generate digital codes. The selected weapon code is communicated over the RSTAT lines to the FCS.

Fault Select Switches. As many as 63 different fault modes can be selected by entering fault codes using FAULT switches S1 and S2 on the simulator assembly front panel. The FAULT switches set the weapon ground power (PWR) lines to indicate the selected fault. The selected fault code is sent through the ground power circuit to the PIM. The PIM provides communications between the trainer M/LPA and the FCS. The FCS reads the fault code from a current-sensing circuit inside the PIM.

Fuze Circuits. The simulator assembly contains six identical fuze circuits. The fuze circuits test the FCS-to-trainer M/LPA interface. They also allow training for warheads using hazes that are set by the FCS fuze-setter module.

Figure 7-8. Simulator Assembly Functional Block Diagram.

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The FCS interrogates the desired fuze circuit by applying fuze interrogation signals to the fuze power (VX) line, the monitor (MON) line, and the return (RTN) line. This causes the fuze to send a digital signal back to the FCS indicating the fuze detonation time stored in the fuze circuit memory.

The FCS sets the desired fuze circuit in the simulator assembly from 0.2 to 199.9 seconds detonation time by applying fuze-setting signals to the VX line, the MON line, and the RTN line. The fuze circuit stores the fuze detonation time in nonvolatile memory (memory that retains its contents after power is removed).

The FCS set the desired fuze to the dud condition by applying +29.5 2.5 VDC for 250.0 10.0 milliseconds between the MON line and the RTN line.

Ground Power Circuits. The simulator assembly contains six identical ground power circuits. The ground power circuits test the ground power (PWR) lines between the FCS and the trainer M/LPA and send the selected fault code to the PIM. Refer to figure 7-9 for ground power circuit operation. The FCS momentarily applies +24 VDC between the ground power (PWR) and ground power return (PWR RTN) lines of the selected ground power channel. This charges a capacitor between the PWR line and the RTN line. Note that the PWR RTN line and the RTN line are connected at the single point ground in the FCS. The metal oxide semiconductor field-effect transistor (MOSFET) is turned on when the FAULT switch is set to close the contacts connected to the appropriate ground power circuit. This allows the capacitor to discharge through the PIM's current-sensing circuit. The PIM's current-sensing circuit produces a fault code, which is read by the FCS computer.

Figure 7-9. Ground Power Circuit.

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The six ground power circuits are connected as follows:Circuit 1: W56J2 pin 6 (PWR RTN 1) and W56J2 pin 8 (RTN 1).Circuit 2: W56J2 pin 14 (PWR RTN 2) and W56J2 pin 16 (RTN 2).Circuit 3: W56J2 pin 22 (PWR RTN 3) and W56J2 pin 24 (RTN 3).Circuit 4: W56J2 pin 31 (PWR RTN 4) and W56J2 pin 33 (RTN 4).Circuit 5: W56J2 pin 39 (PWR RTN 5) and W56J2 pin 41 (RTN 5).Circuit 6: W56J2 pin 47 (PWR RTN 6) and W56J2 pin 49 (RTN 6).

Guided Missile System Test Set

The guided missile system test set (GMSTS) is a manportable test set that provides the operator with the capability to ascertain the go or no-go condition of the ATACMS missile while it is in the MLP/C. The GMSTS controls power application to the missile, enables communication channels, and downloads and executes missile self-test software. It also reports test results to the operator and provides long-term storage of the results for future analysis. The major components of the GMSTS consist of the test unit, the power supply assembly, and the test accessories kit (figure 7-10).

DC input power to the GMSTS is provided by either a vehicle, using a NATO slave connector supply assembly, a PU-619M motor generator, or the power supply assembly.

Figure 7-10. Guided Missile System Test Set.

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Test Unit. The test unit consists of the following assemblies: a standard test equipment-expandable (STE-X) mainframe, a power module assembly, a hardware interface module, a memory module, and a set communicator (SETCOM). The front panel of the test unit is shown in figure 7-11.

STE-X Mainframe. This is a common piece of test equipment presently in the Army inventory The STE-X mainframe, with the appropriate Deep Attack hardware interface module and applications software, is able to communicate, control power, monitor built-in test (BIT) functions, monitor the results of calibration tests, initiate fin motion tests, and determine the overall go or no-go condition of the missile.

Primary input power (+24 VDC) is applied to connector J1 of the STE-X mainframe using cable assembly CX-71. The STE-X mainframe interfaces at connector J2 with the SETCOM through cable assembly CX-50. Connector J4 provides an interface to a line printer while J3, J5, and J8 are not used during testing of the Deep Attack missile. The mainframe ON/OFF switch (S1) applies input power to the mainframe circuits.

Upon initial application of power the GMSTS automatically initiates a power-up confidence test of the digital circuits in the STE-X mainframe to

Figure 7-11. GMSTS Test Unit Front Panel.

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ensure that the GMSTS is capable of executing a self-test. If a failure occurs, the fault is displayed in the form of an error code to the operator on the SETCOM. The error code identifies the major malfunctioning assembly. If no fault is found, the system will be initialized.

The STE-X mainframe consists of a master CPU, three slave processors, and memory. The memory consists of 750 K words of nonvolatile reprogrammable mass storage (NRMS) memory, 256 K words of dynamic random access memory (DRAM) and 24 K words of static random access memory (SRAM).

The master CPU is capable of communicating with the missile's inertial guidance unit (IGU) through the hardware interface module's RS-423A data channels. It has direct access to the NRMS and DRAM memory through the main CPU bus. In general, the master CPU provides for the execution and control of all missile testing once it has been supplied with the appropriate Deep Attack software.

Two analog measurement slave processors in the mainframe interface with the analog measurement channels in the hardware interface module for the purpose of voltage sensing. Software monitors the power lines to the missile for undervoltage (+23 VDC) and overvoltage (+30 VDC) or overcurrent (maximum 6.5 amps per channel) conditions. If an undervoltage, overvoltage, or overcurrent condition occurs at the M/LPA interface, the power and communication channels are automatically disconnected. Each slave processor accesses an RS-232 SIO port that allows it to interface with peripheral equipment.

The third slave processor interfaces the SETCOM directly with the main CPU.

Power Module Assembly. The power module assembly accepts +24 VDC input power and provides the required operating voltages (+5 VDC to +60 VDC) for test unit operation.

Hardware Interface Module. The hardware interface module serves as an interface between the STE-X mainframe microprocessor and the Deep Attack missile for the purpose of testing. It is accepted by the mainframe and configures the GMSTS to the specific analog and digital measurement and stimulus requirements of the missile. The hardware interface module consists of a front panel and six CCAs. (See figure 7-12.)

The front panel of the hardware interface module consists of three connectors (J6, J7, and J9), a GMSTS POWER ON indicator (DS2), a MISSILE POWER ON indicator (DS1), an ELAPSED TIME indicator (M1), a MISSILE POWER ENABLE switch (S2), and a MISSILE POWER ENABLE indicator (DS3).

Connector J6 (input power) connects +24 VDC input power to the hardware interface module through cable assembly CX-71P2.

Connector J7 (missile power) connects missile power and test signals to the missile under test through cable assembly CX-70.

Connector J9 (self test) provides a wraparound test circuit for cable assembly CX-70 during the GMSTS self-test. Cable assembly CX-70P2 connects to this connector.

The GMSTS POWER ON indicator (DS2) indicates that power is applied to the GMSTS.

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Figure 7-2. GMSTS Hardware Interface Module CCAs.

The MISSILE POWER ON indicator (DS1) indicates that missile power is available.

The ELAPSED TIME indicator (M1) is a non-resettable total time indicator used to display the total operating hours of the GMSTS.

The MISSILE POWER ENABLE switch (S2) controls missile input power to the hardware interface module.

The MISSILE POWER ENABLE indicator (DS3) indicates that missile input power is applied to the hardware interface module.

The six CCAs consist of one RS-423A communications CCA, two power-switching CCAs, one power-protection CCA, and two input multiplexer CCAs.

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The RS-423A communications CCA consists of six serial communication channels that serve as an interface between the test unit and the missile. Data transfer between test unit and the missile is across six 3-wire RS-423A serial data channels operating at a rate of 19,200 bps.

Along with serving as a communication link, this CCA also controls the missile power-switching circuits. This control ensures the simultaneous switching of missile power to all channels, thus precluding any one channel from supplying all the current.

This CCA also acknowledges the occurrence of all data transmission interrupts between the missile and the test unit. These include all power status (overcurrent, undervoltage, and overvoltage) interrupt conditions.

Finally, this CCA contains relays to provide isolation between the unused communication channels and the missile. These relays also serve to loop back the outputs of the RS-423A drivers to permit a comprehensive self-test of the CCA during the GMSTS self-test operation.

The power-switching CCAs (A1 and A2) are two identical CCAs, each containing three 2-wire power channels. The power-switching CCAs work together with the power-protection CCA and provide up to six +24 VDC, 4 amp power channels to the missile. Each power channel is monitored for an overcurrent, overvoltage, or undervoltage condition. If a fault condition is sensed, power to the missile is removed.

Four of the six power channels are activated simultaneously during the initial power-up of the missile. These channels are used to power the on-board missile electronics.

The remaining two power lines are activated prior to the initialization of the internal built-in test (IBIT) function, and power is removed upon completion of the test. These power lines supply operational power to the control actuator system (CAS) on board the missile.

The power-protection CCA (A3) is used to monitor the input power to the hardware interface module. If the input power varies below +23 VDC or above +30 VDC, or if the ripple voltage is greater than 4 volts root mean square (RMS), the power-protection CCA (through the power-switching CCAs) will remove power from the missile.

The input analog multiplexer CCAs (A5 and A6) receive analog voltage and current measurement signals from the missile and convert these signals to digital data for use by the STE-X mainframe. They also receive digital data from the mainframe and convert them to analog signals.

Memory Module. The memory module consists of 128 K words of- field-programmable plug-in NRMS memory. It contains all the software that is required for the main CPU in the STE-X mainframe to test the Deep Attack missile. After it is initially downloaded from the plug-in module, the GMSTS software resides in the mainframe bubble memory (NRMS).

Set Communicator. The SETCOM (figure 7-13) is the interface between the operator and the GMSTS. The front panel displays 72 alphanumeric characters in two lines of 36 characters each. The messages displayed consist of the operator's keyboard entries, step-by-step instructions to the operator, error messages, queries for operator observations, test results displays, and messages

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Figure 7-13. GMSTS Set Communicator.

identifying defective assemblies and components within the GMSTS. A numeric keyboard is provided to allow the operator to input test numbers, respond to test step questions, and issue commands to control the test flow. Digital multimeter capability is also included as part of the SETCOM function with the use of test probe cable W2.

Power Supply Assembly. The power supply assembly consists of the power supply panel and the combination case and contents

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Power Supply Panel. The power supply panel (figure 7-14) converts 110 VAC to 240 VAC, 50 to 400 Hz, input power to +26.4 VDC, 31.4 amps output power for test unit operation and missile testing. The exterior of the panel assembly contains input and output power connectors, an ON/OFF switch, an-d a POWER ON indicator.

The POWER IN connector (J1) is the AC input connector to the power supply panel. The AC power source is routed to connector J1 through the AC primary power cable (CX-72).

The POWER OUT connector (J2) is the DC output connector to the test unit. Connector J2 provides the test unit with +26.4 VDC through the DC power cable (CX-71).

The ON/OFF switch (S1) is a 15-amp circuit breaker that applies the AC input power to the power supply panel.

The POWER ON indicator (DS1) indicates that +26.4 VDC output power is available to the test unit.

Combination Case and Contents. The combination case serves as a storage container for the power supply accessories and the power supply panel. It contains a solar shield, a 115 VAC primary power cable, and a 220 VAC power adapter. The solar shield is a vented aluminum shield that is used as an umbrella to protect the power supply panel from heat and solar radiation. The AC primary power cable assembly (CX-72) is an eight-foot cable that connects the 115 VAC, 60 Hz input power to the power supply panel assembly. The AC power adapter (CA-76) converts the primary power cable (CX-72) to a 240 VAC, 50 Hz configuration. CA-76P1 connects to CX-72P1.

Test Accessories Kit. The test accessories kit contains a solar shield for the STE-X mainframe, a CA-75 NATO slave adapter, cable assemblies CX-70 and CX-71, and a test probe case.

SURVEILLANCE AND VERIFICATION TEST

The surveillance and verification test is a two-part test designed to determine the overall go or no-go status of the missile. The test is performed at the ammunition supply point (ASP) using the GMSTS. The surveillance and verification test is performed annually on approximately 20 percent of the missiles stored in the ASPs. It is also performed upon receipt of the M/LPAs at the ASPs and after the M/LPAs have been returned to the ASPs from the using units. The verification test ensures that the missile's electronics are functioning properly. The surveillance test verifies the inertial guidance unit (IGU) calibration. The two tests may be run independently or in conjunction with each other.

Pretest Operations

Prior to testing, the test personnel should review the M/LPA records for any previous deficiencies, verify the information on the M/LPA calibration label, and perform a self-test of the GMSTS.

Test Area Requirements. Prior to performing the surveillance and verification test, the M/LPA must be leveled to within four degrees in elevation and

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Figure 7-14. GMSTS Power Supply Assembly.

roll. A compass-oriented reference line must also be established to within four degrees of true north. This reference line is used to orient the M/LPA to the north prior to testing. The latitude and longitude in degrees, minutes, and seconds, along with the altitude in meters from sea level of the test site, are also required.

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GMSTS Hookup. The GMSTS may be configured with either an AC or a DC external power source (figure 7-15). With an AC input, the DC power cable (CX-71P1) is connected to J2 on the power supply assembly. CX-71P2 is connected to J6 on the test unit, and CX-71P3 is connected to J1 on the test unit.

The missile power cable (CX-70P1) connects to J7 on the test unit, with CX-70P2 connecting to J2 on the M/LPA. The SETCOM cable (CX-50P1) connects to J2 on the test unit, and CX-50P2 connects to J1 on the SETCOM. The AC primary power cable (CX-72P2) connects to J1 on the power supply assembly, and CX-72P1 connects to the external 110 VAC, 60 Hz power source. If a 220 VAC, 50 Hz power source is to be used, the AC power adapter (CA-76) connects to CX-72P1.

Figure 7-15. GMSTS Power Interconnect Diagram.

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With a DC power input, the same hook-up configuration applies, except that the DC power cable (CX-71P1) connects to the external DC power source. Cable adapter CA-75 is used to adapt cable assembly CX-71P1 to a NATO slave receptacle configuration.

Test Procedures

The surveillance and verification test consists of the GMSTS initialization, the missile power-up sequence, the missile IBIT function, the load and purge function, and the surveillance test.

GMSTS Initialization. Upon completion of the GMSTS self-test, the surveillance and verification test is initiated when the operator selects the ATACMS test option through the SETCOM. Once the test is initiated, the operator enters the calendar date, the time of day and the part number and serial number of the M/LPA. The main M/LPA test program then verifies the M/LPA part number and serial number with the applications program version. If the part number and serial number match the applications program version, the main M/LPA test program then loads the applications program from bubble memory to operating RAM for execution. The applications program prompts the operator to connect the GMSTS to the M/LPA and then executes the following GMSTS-to-M/LPA interface checks.

The GMSTS verifies that the CX-70 cable is connected to M/LPA connector J2 (pins 50 and 51). If this connection cannot be verified, power application to the missile is inhibited.

The GMSTS checks the safe continuity loop (J2 pins 53 and 55) of the missile. If an open circuit is detected, the SETCOM will display MISSILE FAILURE to the operator.

The GMSTS checks the SAFE/ARM loop (J2 pins 53 and 54) of the missile. If a short circuit is detected, the SETCOM will display MISSILE FAILURE to the operator.

Missile Power-Up Sequence. The GMSTS connects four of the six external power channels to the missile. These four power channels provide +24 VDC operating power to the on-board electronics. Upon the application of power, the missile electronics perform a power-up BIT consisting of a memory read/write and verify test, a resident program memory error check, and an interprocessor communication test.

A memory read/write and verify test is performed on each byte address in RAM of the guidance and navigation computer (GANC), the inertial sensor assembly computer (ISAC), and the control system electronics unit (CSEU) within the missile. This tests the processors' ability to write into and read out of the RAM modules.

A load verification is performed on the resident program memory area (EEPROM) of each processor. This is performed by summing horizontal and vertical totals (checksums) and adding these totals to complemented checksums obtained when the software load module was manufactured. The sum of the totals is then sent to the GMSTS. If the sum equals zero, a go status is indicated.

An interprocessor communication test is performed to check the communication interfaces between the three on-board processors.

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At the completion of the power-up BIT, the GMSTS establishes communications with the missile by requesting the part number and serial number of the IGU and the CSEU within the missile. The missile configuration ID and software operational program version are then compared to that within the GMSTS. If the software versions do not match, the GMSTS loads the latest software version from the test unit to the missile.

Missile Internal Built in Test Function. The missile IBIT consists of the BIT functions of the IGU and the CSEU and a missile status report.

Prior to initiating the missile's IBIT function, the GMSTS applies two additional +24 VDC power channels to the missile. The additional power channels provide operating power to the CAS for operation of the control fin actuators.

The IBIT function is a comprehensive self-test of the missile's electronics assemblies. During the IBIT, a computer self-check is performed on the three on-board computers (the GANC, the ISAC, and the CSEU). Artificial signals are applied to the accelerometers, and the results are checked. Artificial signals are also applied to the gyro pulse accumulator module, and the results are checked. Calibration processing checks, gyro and accelerometer temperature checks, power supply output checks, analog/digital (A/D) reference voltage checks, and a fin motion test are performed.

The missile status report indicates the status of various subassemblies within the missile. If a failure exists, the operator is prompted of a MISSILE FAILURE, and power is removed from the missile.

During the missile status report, the GMSTS verifies that the missile indicates it is NOT READY FOR LAUNCH, that the missile is NOT ON INTERNAL POWER, that the warhead SAFE/ARM/FIRE device is NOT ARMED, that the solid rocket motor (SRM) ARM/FIRE device is NOT ARMED, that the SRM is SAFE, that there is no internal communication failure, that the warhead SAFE ENABLE COMMAND IS NOT SENT, and that the CSEU indicates it is NOT IN FLIGHT MODE.

Upon completion of the IBIT, the results of this test along with the results of the 10 previous tests are stored in the missile's memory and then transmitted and logged into the test unit's memory. Also at this time, the two additional power channels that were used to power the CAS are removed from the missile.

Load and Purge Function. The load and purge function tests the IGU's ability to load and purge data in the classified data memory locations. Simulated classified data are sent to the missile, where they are downloaded and verified in the appropriate memory locations. Once downloaded, the data are purged at the operator's request. If a failure occurs, the operator is prompted via the SETCOM.

Surveillance Test. With the test area requirements met and the M/LPA positioned so that the left side of the LP/C straddles the north compass-oriented reference line, the operator enters the initial conditions on the SETCOM keyboard. The initial conditions consist of the calendar date, the time of day, and the latitude, longitude, and altitude of the test site.

The GMSTS then performs an orientation verification to ensure that the M/LPA is level to within four degrees. If the elevation or roll orientation is not correct, the operator is prompted of the incorrect orientation and instructed to level the M/LPA to within four degrees.

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The initial conditions are sent to the missile, and the IGU enters the first of two surveillance calibration (S-CAL) modes. The operator is then prompted S-CAL 1 IN PROGRESS, APPROXIMATELY “#” MINUTES REMAINING.

The calibration gimbal in the IGU unlocks and rotates the inertial sensor assembly 360 degrees in twelve 30-degree increments. The test runs without operator intervention. If a failure is detected, the operator is prompted of the failure and the GMSTS initiates the missile power-down sequence. During the rotation, three new velocity parameters, three new altitude parameters, three new gyro biases, three new accelerometer biases, and three new accelerometer scale factors are determined.

Upon completion of S-CAL 1, the operator is prompted S-CAL 1 MODE COMPLETE, and the GMSTS commands the IGU to the rotation mode. During the rotation mode, the IGU begins supplying attitude data to the GMSTS. These data are decoded to display the azimuth orientation of the M/LPA to the operator on the SETCOM.

The operator is then prompted to rotate the M/LPA due east to within four degrees. During the rotation, the GMSTS maintains missile ground power to the missile and activates a 10-minute M/LPA rotation countdown timer. If the timer expires prior to the M/LPA being repositioned, all further testing is terminated.

Once the M/LPA is positioned east, the GMSTS performs an orientation verification to ensure that the M/LPA is level to within four degrees. If the elevation or roll orientation is not correct, the operator is-prompted of the incorrect orientation and instructed to level the M/LPA to within ± four degrees.

The GMSTS then transmits the initial conditions to the IGU, and the IGU enters the S-CAL 2 mode of operation. The operator is prompted S-CAL 2 IN PROGRESS, APPROXIMATELY “#” MINUTES REMAINING. The calibration gimbal unlocks and rotates the inertial sensor assembly 360 degrees in twelve 30-degree increments to determine a second set of data.

Upon completion of S-CAL 2, the operator is prompted S-CAL 2 MODE COMPLETE. The GMSTS then requests the latest calibration results, along with up to 10 previous calibration results stored in the missile's memory. The new data are compared with the previous calibration results. A trend analysis is performed on the new data to determine their acceptability. If the data are acceptable, an ACCEPT S-CAL DATA command is sent to the missile, and the new data are added to the calibration parameter storage area in IGU memory along with the test date and time. If the data are rejected, the operator is prompted CAL DATA REJECTED and the missile is powered down.

Missile Maintenance

Maintenance on the ATACMS missile is performed only at the depot level. If the missile fails any part of the surveillance and verification test, it is routed back to the depot for repair. Maintenance on the missile will also include a depot-level calibration of the IGU. This is presently scheduled once every three years; however, due to the long-term stability of the ring laser gyros and the limited operating time expected, the interval is expected to be extended to once every ten years.

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REVIEW EXERCISES


1. How many auxiliary processors that perform computational tasks does the electronics unit on the M270 launcher contain?

a. Two.b. Three.c. Four.d. Five.

2. How often is the surveillance and verification test performed on the Missile/Launch Pod Assembly of the Deep Attack Missile System?

a. Monthly.b. Quarterly.c. Semiannually.d. Annually.

3. What level of maintenance is authorized on the ATACMS missile?

a. Organizational.b. Direct support.c. General support.d. Depot.

4. What is the purpose of relay K5 in the power distribution box on the M270 launcher?

a. It ensures that relay K3 in the EB is deenergized prior to energizing of the LDS.b. It provides power to the FCS batteries.c. It provides power from the FCS to the on-board weapons.d. It directs output power to J6 and J7.

5. How many assemblies make up the guided missile system test set test unit?

a. Three.b. Four.c. Five.d. Six.

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6. How many alphanumeric characters are displayed on the set communicator?

a. 55.b. 72.c. 96.d. 128.


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EXERCISE SOLUTIONS

LESSON 1 LESSON 4

1. b (see page 8). 1. a (see page 61).2. c (see page 15). 2. a (see page 69).3. a (see page 4). 3. d (see page 62).4. a (see page 17). 4. c (see page 62).5. b (see page 16). 5. d (see page 60).6. a (see page 12). 6. c (see page 60).

LESSON 2 LESSON 5

1. c (see page 24). 1. a (see page 74).2. a (see page 23). 2. d (see page 74).3. d (see page 25). 3. b (see page 77).4. b (see page 27). 4. b (see page 83).5. a (see page 31). 5. a (see page 90).6. b (see page 32). 6. b (see page 90).7. a (see page 34).8. d (see page 35). LESSON 69. c (see page 36).

10. d (see page 36). 1. a (see page 132).11. b (see page 37). 2. c (see page 136).12. b (see page 38). 3. b (see page 94).13. c (see page 38). 4. d (see page 94).14. a (see page 38). 5. c (see page 94).15. c (see page 38).16. b (see page 39 LESSON 717. c (see page 40).

1. a (see page 156).LESSON 3 2. d (see page 170).

3. d (see page 175).1. b (see page 48). 4. a (see page 161).2. c (see page 47). 5. c (see page 165).3. b (see page 54). 6. b (see page 168).4. d (see page 57).5. d (see page 49).

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multiple launch rocket system

Documents

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mlrs components

control system menus

control system fcs

c3 system net

primary power system

freeflight rocket system