sabre liner

1

SABRELINERMAINTENANCE MANUAL

NA-69-420(2) In cockpit, place both BATTERY switches at OFF.

(3) Remove access doors from each side of battery compartment.(4) Disconnect battery cable quick disconnect connectors and sensor

plugs. Install dust cap on sensor plugs. Temporarily insulateand stow cable quick disconnects.

(5) Disconnect vent hoses from batteries and from sump jar. Removesump jar and loose vent hoses from airplane. Protect all

openings.(6) Remove battery tie-down straps and rods.

(7) Remove batteries from airplane.B. Checking Battery

Examine battery for evidence of the following conditions:(1) Damage and distortion of battery case and cover.

(2) Burned or damaged contacts on external electrical power receptacle.(3) Cracks and evidence of leakage on top of each battery cell.

(4) Security of cell connectors. Check condition and security of batterytemperature sensor(s).

(5) Evidence of corrosion on and around cell connectors and cell vent caps.(6) Cracks, corrosion, deterioration, and leakage of all cell vent caps.

C. Discharging BatteryNOTE: The battery must be fully discharged before any attempt is made

to disassemble the battery. Following the addition or distilledwater to the battery cell electrolyte, the battery must be discharged

as part of the cycling procedure required to thoroughlymix the electrolyte with the distilled water added to the cells.

The battery is also discharged to reveal the presence of a faultycell or cells.

To discharge battery, proceed as follows:(1) Obtain a suitable load bank which is continuously variable from O

to 5 ohms, has a 600-watt capacity, and is equipped with a deammeter capable or reading 20 amperes of discharge current.


NA-69-420(2) Connect load bank to battery, and adjust load bank resistance to

cause a discharge current as applicable to battery installed: 11amperes for 22-am-pere-hour battery or 17 amperes for 34-ampere-hour

2

battery.(3) Time discharge operation for a ii-hour period.

(4) At 15-minute intervals during discharging procedure, check eachindividual battery cell terminal voltage. Use a O- to 5-volt de

voltmeter.(5) Mark (or otherwise identify) any cell whose terminal voltage drops

below 0.95-volt de during 2-hour discharging period.NOTE: All cells having a terminal voltage of less than O.95-volt

ac at the completion or the 2-hour discharge period (or anycells that reverse polarity) are considered to be suspect

and should be marked for possible replacement. (Refer toprocedures for cycling battery and testing battery capacity

for further maintenance procedures.)(6) After completion of 2-hour discharge period, resume dischargingprocedurel but at a 5-ampere rate. (Readjust load bank resistance

to establish 5-ampere rate.)(7) Continue checking individual cell terminal voltages periodically.(8) When terminal voltage of a cell drops to 0.50-volt de, short out

cell ~´•rith a suitable jumper wire.(9) When all cells have been discharged and shorted out with individual

jumper wires, disconnect load bank from battery.(10) Leave individual jumper wires connected across battery cells for at

least 8 hours, or overnight.(11) Remove jumper wires from battery cell terminals.

D. Disassembling BatteryNOTE: Before disassembling battery, carefully note positions of cell

connectors and cell separators for subsequent reassembly. (Seefigure 24-308-6.) Use insulated (or taped) hand tools to remove

cell connectors. Use battery cell puller (figure 24-30A-9) toremove cells from battery case.

(1) Disassemble battery as required (see figure 24-308-6).(a) After battery cover is removed, loosen all cell vent caps. (Use

cell vent cap wrench.) Retighten cell vent caps beforeproceeding with disassembly.

(b) Use cell puller (figure 24-30A-9) to remove battery cells frombattery case.

3

SAE~ 6~ E LI N ERMAINTENANCE MANUAL

NA-69-420(c) Stow battery cells in an upright position to avoid possible

spillage of cell electrolyte.(d) Remove cell separators as required during the disassembly

procedure.E, Cleaning Disasserabled Battery

(1) Remove any corrosion from all re-usable parts by brushing partswith a stiff-bristled fiber brush.

(2) Wash all re-usable parts with a 3 percent solution (by weight) ofboric acid asia distilled water. Exercise care to prevent entry ofsolution into battery cells, (Make sure cell vent caps are tight.)

(3) Thoroughly dry all re-usable parts.F. Checking D-isassernblea Battery Parts

NOTE: Replace all parts round to be faulty when checked as outlinedin steps (1) through (T),

(1) Thoroughly check all battery parts for any damage, cracks,deterioration, or excessive ~´•Jear.

(2) Check all threaded parts for crossed or damaged threads.(3) Check individual battery cell cases for evidence of leakage.

(4) Check battery manufacturer’s part number on side of each cell case.All cells should have the correct part number for the battery in

which cells are to be installed.(5) Replace all battery cells found to be unserviceable duricg ~ischarge

procedure.G. Adjusting Specific Gravity of Cell Electrolyte

To check specific gravity of electrolyte in each battery cell, ~roceedas follows:

(1) Wear proper protection during this procedure, such as a faceshield, rubber gloves, and a rubber apron.

(2) Obtain a glass bowl which is absolutely clean.(3) Lodsen and remove battery cell vent cap (use cell vent cap wrench);

then carefully and slowly empty cell electrolyte from cell intoglass bowl. Exercise care to avoid splashing and loss of electroly-

4

SABRE LI N ERMAINTENANCE MANUAL

NA-69-420(4) Obtain a hydrameter designated only for nickel-cadmium battery

servicing.(5) Insert end of hydrometer into electrolyte contained in glass bowl.

Suck up electrolyte into barrel of hya~oraeter.(6) While holding hydrometer in a vertical position over glass bowl,

note specific-gravity reading. The reading should be between1.24 and 1.32. Return electrolyte to glass bowl.

(7) If specific gravity of electrolyte measures above 1.24, returnelectrolyte to battery celt. (Use hydrameter to transfer electrolyte

from glass bowl to battery cell.)Install cell vent cap on battery cell. (Use cell vent cap wrench.)

Do not overtighten cell vent cap.(9) If specific gravity of cell electrolyte is below 1.24, obtain a

30 percent solution (by weight) of potassium hydroxide and aistilledwater.

(10) Mix a small portion of 30 percent solution into cell electrolytein glass bowl. (Do this slowly and carefully, and gently stir

electrolyte while adding solution.)CAUTION: IT IS STRONGLY RECOMMENDED THAT TKE 30 PERCET\JT

SOLUTIONOF POTASSIUM HYDROX~E AND DISTILI;ED WATER BE OBTPlNEDIN READY-MIXED FORM, RATHER TKAN ATTEMPTING TO LOC~IT;Y

MIX THE SOLUTIO~J. IMPROPER MIXING PROCEDURES MAY RESULTIN A VIOLENT EXPLOSIVE REACTION.

(11) Repeat steps (5) and (6) to recheck specific gravity of electrolyte.(12) When specific gravity of electrolyte is within specifications,

return electrolyte to battery cell.(13) If required, repeat steps (3) through (12) for remaining battery

cells.(14) Check electrolyte level in all battery cells. Adjust level, if

necessary, using hydrometer or syringe.H. Assembling Battery

(1) Assemble battery in reverse order of disassembly (figure 2 4-3 OA-6noting the following:

(a) Check polarity of each cell before installing cell in batterycase.

5

SABRELINEIRMAINTENANCE MANUAL

NA-69-420(b) Check manufacturer’s part number on side of each cell, before

installing cell in battery. All cells must have the correctpart number for the battery in which the cell is to be installed.

(c) Install battery cells according to polarity diagramshown in figure 24-30A-6.

(d) Insert cell separators (if removed) as required during theassembly procedure.

(e) Tighten cell connector socket-head cap screws to a torquevalue not to exceed 35- to 50-inch pounds.

I. Charging BatteryTo charge battery after it has been assembled, proceed as follows:

(1) Connect battery to a shop dc generator system. Observe pro-eerpolarity connections to de generator system (positive terminal of

battery connected to positive terminal of de generator).(2) Turn on de generator system, and adjust to an output of 28.5-volt

de. Note de generator system charging current perioaicallZI(3) When charging current decreases to approximately 10 amperes or

less, turn off de generator system temporarily.(4) Connect a O- to 25-ampere de ammeter in series with batter;.

Observe proper polarity in connection to de anuneter.(5) Turn on de generator system, and resume charging procedure.

(6) Observe O- to 25-ampere de anuneter periodically. When ammeterindicates a charging current of one ampere or less, turn de

generator system.(7) Disconnect battery from de generator system.

;r. Cycling BatteryThe battery cycling procedure consists of completely discharging, thenrecharging, the battery. A battery should be cycled immedia’cel~ after

distilled water has been added to the battery cell electrolyte. Thebattery should also be cycled whenever it becomes necessary to attempt

correction of a cell unbalanced condition, or to correct a reversal ofpolarity of one or more cells in the battery. To cycle battery, ~roceed

as follows:(1) Completely discharge battery. (Refer to procedure for discharging

battery.)(2) Charge battery. (Refer to procedure for charging battery.)

6


NA-69-420K. Testing Capacity of Battery

To test capacity of a battery, proceed as follows:NOTE: Make sure that battery is fully charged and that electrolyte

level in battery cells is correct, before making a capacity testof battery.

(1) Obtain a suitable load bank (continuously variable from O to 5 ohms),having a 6oo-watt capacity, and equipped with a de ammeter capable

of reading 20 amperes of discharging current.Connect load bank to battery. (Observe proper polarity so that de

ammeter will indicate aischasging current correctly.)(3) Adjust load bank resistance to cause a discharge current of

17 amperes.(4) Time discharge operation for a 2-hour period.

(5) At 15-minute intervals during 2-hour discharging period, checkterminal voltage of battery. (Use a O- to 25-volt de voltmeter.!

If battery terminal voltage drops below 18.0-volt de before completionof 2-hour period, discontinue test. This indicates tha~

the battery has failed the capacity test.(6) At completion of 2-hour discharging period, disconnect load banlr

from battery.(7) ’Measure battery terminal voltage. The voltage should measure18.0-volt de or above, if the battery has passed the capacity test.(8) Recharge battery. (Refer to procedure for charging battery,)

TJOTE: A battery which fails to pass the capacity test may have 8cell (or cells) unbalance condition, or a reversal of

polarity of one or more cells. This condition may possiblybe corrected by cycling the battery. After cycling, thebatter; should be given the capacity test; again. If the

’battery fails to pass the second capacity test, the batter3ishould be fully discharged, and defective cells should be

replaced. After cells have been replaced, the batteryshould be charged and then given the capacity test.

L. Installing BatteriesWARNING: WEAR PROTECTIVE CLOTHING TO AVOID CAUSTIC BURNS.

WHEN MOVIB"JBATTERIES USE CARE TO AVOID SPILLING ELECTROLYTE USE CARE TO

AVOID INJURY WHEN LIFTING BATTERIES. EACH BATTERYWEIGHS 84 POUNDS.

(1) Remove all electrical power from airplane.

7

SAI~aE bI: aMAINTENANCE MANUAL

NA-69-420(2) In cockpit, check that both BATTERY switches are positioned at OFF.

(3) Inspect battery compartment for cleanliness and inspect batterysupport trays to ensure that insulator strips are in place.

(4) Check that battery covers are securely fastened.(5) Place batteries onto support trays. Make sure that connectors are

facing outboard on each side.(6) Secure batteries in place with tie-down straps and rods.

(7) Service sump jar(if require~) and install sump jar and all venthoses.

I (8) Check quick disconnect plug pin sockets for looseness. Insertaf2 pounds.steel pin 0.375 f 0.00’05 inch diameter) a distance of one-half

inch into each socket. Record force required to remove pin. Theminimum removal force is one pound. The desired removal force is 5

(9) Install cable connectors and sensor plugs. Safety wire.(10) Inspect compartment and components´•for cleanliness and security.

(11) Close access doors.(12) Perform test of battery system.

(13) Perform operational check-out of battery temperature system.2. Servicing Battery Vent System

A. To service battery sump jar, proceed as follows:(1) Remove access door on left side of fuselage nose.

I (2) Remove vent hoses from sump jar. Inspect tubes for visible damageand/or obstructions.

(3) Remove bolts securing sump jar to tray.(4) Remove sump jar pad.

(5) Saturate pad with a 3 percent (by weight) solution of boric acid andwater. Use only enough solution to saturate pad.

(6) Replace pad in sump jar and install sump jar lid.(7) Place sump jar on battery tray and secure with bolts.

(8) Connect battery vent hoses.

+


8

NA-69-420(9) Install access door.

B. Service battery system vent and drain tubes as follows:WARNING: DO NOT PUT MOUTH IN DIRECT CONTACT WITH AN OPEN END

OF ABATTERY SYSTEM VENT OR DRAIN TUBE AS A MEANS TO BLOW CLEAR

ANYOBSTRUCTION IN TUBE. FAILURE TO OBSERVE THIS WARNING CANRESULT IN SEVERE MOUTH AND THROAT BURNS TO MAINTENANCE

PERSONNEL.(1) Observe battery servicing precautions.

(2) Disconnect lower end of vent or drain tube and place it in a glassjar.

NOTE: Do not permit any accumulation of electrolyte or moisture invent or drain tube to drip onto airplane structure.

(3) Apply dry air pressure to upper end of vent or drain tube.NOTE: Use a 2 to 5 psi dry-air pressure source to clear any

obstructions in vent or drain tubes.(4) Continue blowing dry air down vent or drain tube to remove

obstruction.(5) If obstruction cannot be removed, completely disconnect section of

vent or drain tube and remove it from airplane. Replace faultysection with a new tube.

(6) Connect lower end of vent or drain tube; then remove glass jar fromairplane.

3. Nickel Cadmium Battery InspectionNOTE: Polystyrene cell cases found in any battery must be replaced with an

equivalent cell having a nylon cell case or the battery must bereplaced with an equivalent battery which contains approved nylon

cells.Page

9

SABRELINERMAINTENANCE: MANUAL

NA-69-420A. To inspect batteries, proceed as follows:

(1) Remove access door on left side of fuselage nose.(2) Disconnect tiedown rods, unlatch and lift battery cover.

(3) Inspect cell links and cell tops for evidence of heat damage.(4) If battery is round to have evidence of heat damage, the batterymust be replaced with a serviceable battery. Service battery´•sumy,

jar if necessary.(5) Close and latch battery cover and secure with tiedown rods.

(6) Install access door.3A. Battery Maintenance Following An Overtemperature Condition

WARNING: NICKEL~CADMIUM BATTERIES ARE SUBJECT TO PHYSICAL DAMAGE AND

GASSI~G IF OPERATED (CHARGED) AT HIGH TEMPERATURES. THERMALRUTV’AWA‘J DURING CHARGING CAN RESULT IN ´•BATTERY FIRE OR

EXPLOSION.NOTE: Thermal runaway of a nickel-cadmium battery can occur only when

connectedto a charging source. Continual charging at high temperatures

can cause decomposition of the water (electrolysis) resulting in thegeneration of additional heat. A high temperature lowers internalresistance resulting in a higher charging current flow which, in tur

can cause a faster rate or gassing (water decomposition) and moreheat. If allowed to continue, this condition can lead to complete

self destruction and severe internal arcing.Improper liquid level, cell imbalance, loose intercell connectors,

and damaged or leaking cells can cause excessive battery operatingtemperatures.

A. Procedure Following a Battery Hot IndicationIf a battery HOT condition was indicated (during flight or check-out of

airplane) by the battery temperature indicator, the affected battery(or batteries) should be removed from the airplane, for checking, cycling,

and (if necessary) repair. (Refer to "Checking, Cycling andRepairing Battery".)

B. Procedure Following a Battery Warm IndicationNOTE: If the battery temperature indicator WARM light illuminated

during a flight, the batteries should be inspected to preventpossible battery failure.

(1) Remove all external electrical power from airplane.(2) In cockpit, place both BATTERY switches at OFF.

10

SABRELIN.ERMAINTENANCE MANUAL

NA-69-420(3) Remove battery compartment access doors from either side of

fuselage nose.(4) Loosen and remove battery tiedown straps, and unlatch and remove

covers from both batteries.(5) Inspect battery cell tops and intercell connectors for any evidence

of heat damage, electrolyte spewage, and cell damage (celldistortion or leakage).

(6) Using a vent cap tool, loosen cell vent caps.NOTE: Do not attempt to measure liquid levels if battery is (discharged)

as liquid is absorbed into plates resulting in afalse liquid level indication.

Do not attempt to measure specific gravity of electrolyte.(7) Using a clean polystyrene tube, check liquid level in each cell.The liquid level should be about 1/8-inch above top of cell plates(1/4-inch immediately after receiving a charge, 1/8-inch three ormore hours after receiving a charge). To use tube, insert end of

tube through vent opening (remove vent cap) until stopped by plates.Place finger over top of tube and carefully withdraw tube until lowe

er end can be seen. (Do not move tube away from vent opening sinceelectrolyte might spill out.) Observe height of liquid in lower

end of tube, then release liquid into cell by releasing finger fromtop of tube. (The tube used should be straight, about six inches

long, about l/s-inch inside diameter, and open at both ends. Tubemay be of glass, but polystyrene is recommended. Tube mustbeclean

and must never have been used with acid.)CAUTIOM: ~SED IN NE~T STEP I´•TijST BE FREE OF A;JY

CONTAT´•IINATION WILL RENDER THE BATTERY USELESS IN A VERYSHORT TIME.

(8) If liquid observed in tube (step 7) is less than required add asmall amount of distilled or demineralized water. If liquid is too

low to be observed in tube, the battery should be removed from theairplane for checking and cycling.

(9) if inspection (step 5) reveals a slight discoloration at ends ofintercell connectors, torque cell connector socket-head screws to

35-50 inch-pounds.(10) If inspection (step 5) reveals an unsatisfactory condition (otherthan noted in steps 8 and 9) remove battery for checking, cycling,

and repair.(11) if inspection (steps 5 and 7) reveals no unsatisfactory conditibn,

replace and tighten vent caps (use vent cap tool), replace andsecure battery covers, and replace battery tiedown straps.

(12) Service battery sump jar (if necessary) and install access doors.

11


NA-69-4204. Removing DC Starter-Generator

NOTE: Each starter-g’enerator is installed on a quick-attach-detach (&AD)adapter on an accessory drive pad on the lower left side of the

respective engine. Except for removal or the lower carling sections(lower outboard on left engine and lower inboard on right engine)~procedures for removing and installing the starter-generator are the

same for both engines.A. To remove de starter-generator, proceed as follows:

(1) Make sure all switches are off and external electrical power disconnected.(2) Open engine cowling section as applicable.

(3) Remove screw securing cooling air duct to engineoverboard drain manlfold.

(4) Remove clamp securing cooling air duct to starter-generator airdischarge fitting and remove duct.

(5) Lift rubber boot from starter-generator electrical terminals andslide up on electrical leads to gain access to terminals.

(6) Disconnect electrical leads from starter-generator terminals. Tagleads for terminal identification during installation procedure.

(7) Loosen 61AD clamp bolt and remove clamp and starter-generator.5´• Installing DC Starter-Generator

A. Flashing DC Starter-Generator FieldNOTE: Before installing a starter-generator, flash the exciter shunt

field tin proper direction) to make certain that shunt fieldretains sufficient residual magnetism. Loss of residual magnetism

will result in f~ilure of the starter-generator to build up´•to proper voltage when operating as a de generator.

Flash shunt field before installing starter-generator in airplane.a A l~-volt battery and a single-pole, single-throw knife switch

are required.Do not make or break battery connection to starter-generator a;

tlAll Or "E-" terminal on starter-generator. To do so will resultin severe damage to terminals.

(1) Connect an insulated wire between negative terminal of a l~-voltbattery and "E-" terminal on starter-generator.

(2) Conn~ct an insulated wire between positive terminal of batteryand one side of single-pole, single-throw knife switch.

12

IMA~INTENANCE PIRACTICES (Continued)3. Openknife switch.

4. Connect an insulated wire from other side ofknife switch to "A" terminal on starter-generator.

5. Close knife switch for 3 to 5 seconds, then openknife switch.

6. Repeat step (5) several times, to make certainthat shunt field is properly flashed.

7. Disconnectknife switchand wiringfrom startergenerator.8. Install starter-generator.

To install DC starter-generator, proceed as follows:i. Make sure all switches are off and external

electrical power disconnected.NOTE

If OAD mounling adagter Iras been removed,i~rsldlgaskel (AN4047-I) andadapierandtorque

refaining nuCs 230 io 325 incR-pounds2. Lubricate starter-generator drive spline with

Plastilube Moly No. 3 or equivalent grease.2k Check oil drain hole, located at lowest point of

ram air inlet duct for any obstruction. Cleanhole as required.

3. Position starter-generator with electrical terminalsand ram air inlet duct facing outboard,

then with starter-generator level, moveforwardand engage starter-generator splines carefully

with accessory drive pad.4. Engage starter-generator alignment pin with

Q~D hole then install QAD clamp.5. While supporting aft end of generator, tighten

clamp bolt. Torque clamp bolt to 150 inchpounds;then back off bolt. Repeat torquing

operation several times until clamp is fullyseated when proper torque is reached.

6. Visually check starter-generator installation toensure thatclamp is properly seated and startergenerator

seated on adapter and properly indexed.7. Safety QAD clamping bolt with lockwire.

8. Connect electrical leads to their respective ter-I minals. (Refer to tags or to Wiring DiagramManual.) Torque 3/16 inch stud nut to 20-30

inch-pounds and 3/8 inch stud nut to 120-130inch-pounds.

9. Slide rubber hood into place over terminals.10. Install cooling air exhaust duct on starter-generator

13

SABPiE1LINE~IMAINTENANCE MANUAL

NA-69-420(11) Insert duct exhaust opening into engine main drain manifold and

secure with screw.(12) Install clamp at starter-generator end of duct and tighten.

(13) Close engine access door.(Ilc) Perform an operational check of de starter-generator,

6, Adjusting DC Generator System Output VoltageNOTE: A.precision O- to 50-volt de voltmeter 16 required to perform this

adjustmentIn the following procedure, the generator output voltage is adjusted

to 28.5 volts de. This voltage is drived to obtain optimum batterylire (due to battery recharge rate) at a standard day temperature of

490F; however, environmental temperatures at which the aircreLft isto be operated may be in a higher tPs~erature range which ultimately

increases the charge rate (due to decreasing internal battery resistance)and reduces battery lire. The following tables list various

recommended voltage settings versus.temperatures st which the aircraftis to be operated. The chests ru~-e applicable to 19 and 20 cell

batteries as noted.Maximum Anticipated Gen. Voltage Beg. Setting-

Ground Temperature With 19 Cell BatteryUp to 300F 29.0v

3lop to 60nF 28.gv61oF to 800F 28,OV810F to 10OoF 27.5v

Over 1000F 2?.ovMaximum Anticipated Gen. Voltage Reg. Setting-

Ground Temperature With 20 Cell BatteryUp to 300F z9.0v

310F to 600F 29.0V610F to 800F 29.OV81oF to 1000F 28.gvOver 1O0oF 28.0V

The lower generator output voltage settings provide a lower batterycharging rate which in turn increases the length or time for thebattery to obtain a full charge. If mission requirements (short

flights) are often encountered, the standard day setting (28.5 volts)may be required to obtain a fully charged battery.

A. To adjust de generator system output voltage, proceed as follows:(1) Remove all electrical power to airplane.

14


NA-69-420Gain access to voltage regulators. Regulators are on the fourth

tray of the relay rack at fuselage station 150.(3) Connect the red (positive) lead of the precision de voltmeter to

the red test jack on the LH generator control unit (CN901). Connectthe black (negative) lead of the precision de voltmeter to

the black test jack on the LH generator control unit.(4) Connect external electrical power to airplane.

(5) Start LH engine. (Refer to Chapter 71.)(6) With the "ELECTRICAL MASTER" and "BATTERY" switches at ON, disconnect

external electrical power from airplane.(7) Position "LH DC GENERATOR" at ON.

(8) Advance engine speed to 75% rpm. Operate engine for 10 to 15minutes at this speed for temperature stabilization of the generator

control unit.(9) Note the left hand generator loadmeter. Load system to approximately

0.25 indication on loadmeter.(10) Position "BATTERY" switches at OFF.

(11) Note the precision voltmeter reading. The meter should read28.5 volts.

(12) If voltmeter does not read 28.5 volts, adjust voltage adjustment(screwdriver slot) on left hand generator control unit until 28.5volts is indicated on precision voltmeter. (Clockwise rotation

of adjustment screw increases voltage.)

15


NA-69-420C13) Position "LH DC GENERATOR" at OFF. Retard engine speed to IDLE

RPM.(14) Connect precision voltmeter to right hand generator control unit

(CNg02) test jacks. Observe correct polarity.(15) Start right hand engine.

(16) Position "RH DC GENERATOR" switch at ON.(17) Advance right engine speed to 75% rpm. Operate engine for 10 to

15 minutes at this speed for temperature stabilization or thegenerator control unit.

(18) Note the right hand generator loadmeter reading. Load system toapproximately 0.25 indication on loadmeter.

(19) Check that "BATTERY" switch’es are at OFF.(20) Note the precision voltmeter reading. The meter should read 28.5

volts.(21) If voltmeter does not read 28.5 volts, adJust voltage adjustment

(screwdriver slot) on right hand generator control unit until28.5 volts is indicated on precision voltmeter (clockwise rotation

of adjus´•tment screw increases voltage).(22) Retard engine speed to IDLE RPM.

(23) Perform procedures in step B.B. To perform parallel adjustment of DC Generator System, proceed as

follows:NOTE: Perform procedures in step A before performing parallel adjustment.

Do not operate AUP during these procedures.(1) Press and hold "PUSH TO TEST RK GEN VOLT" switch. The airplar.e

de voltmeter should read 28.5 volts.If airplane de voltmeter does not read within one percent or precision

voltmeter, adjust airplane de voltmeter instrument adjustmentscrew on face of instrument until indicator reads rl percent

of precision voltmeter. Release test switch.(3) Position "LH DC GENERATOR" at ON.

(4) Press and hold "PUSH TO TEST LH GEN VOLT" test switch. The airplanede voltmeter should read 28.5 volts.

(5) Repeat step (2).

16


NA-69-420NO’lfE: If the cockpit de voltmeter adjustment screw is adjusted,

the zero indication of the meter may be slightly off whenelectrical power is removed from the airplane.

(6) Position "BATTERY" switches at OTJ.(7) Increase de bus load, if necessary, until loadmeter indicates

approximately 0.3 (30 percent) load.(8) Position "LH: DC GETJ" s~ritch at OFF and note loadraeter reading.

(9) Check for 28.5 volts on precision voltmeter.(10) Position "LK DC GEN" switch at OTJ and the "RH DC C;EN" switch at OFF

and note loadmeter reading.(1L) Connect precision voltmeter (preferably a digital voltmeter) to

left hand generator control unit. Observe correct polarity ofthe meter leads.

(12) Check for 28.5 volts on precision voltmeter.NOTE: The loadmeter should read the same in step (8) and (10).

(13) Position "RK DC GEN" switch at ON.(14) Increase right and left engine speed to 65 percent rpm.

(15) Increase load on the de bus system until each loadmeter indicatesone-fourth of full load (100 amperes each generator).

(16) If the generators are not sharing the load las indicated by theloadmeters) within one scale division, the generator control

unit paralleling adjustment must be adjusted.NOTE: When adjusting the parallel potentiometer, --adjust thepotentiometer for the generator that has the highest loadmeter

reading slightly counterclockwise. Adjust theopposite generator parallel potentiometer the same amount

in the clockwise direction.(17) Repeat step (16) until the RH and LK loadmeters are within one scale

division of each other.(18) Recheck system voltage (28.5 VDC) at primary bus. Adjust potentiometers

on generator control units if required. If voltage adjustmentsare performed, recheck generator paralleling subsequent to

voltage adjustment.C. Reverse Current Relay Functional Test

NOTE: Ensure that the voltage and parallel adjustments are correctbefore performing this check.

17

SAE3RE LI N ERMAINTENANCE MANUAL

NA-69-420(1) With a .25 (25 percent) load on the de bus system and the engines

operating at idle rpm, position "RH DC GEN" and "LH DC GEN" generetorswitches at OFF. Check that "BATTERY" switches are positione~

at ON.(2) Position "LH DC CEN" at ON. Slowly increase engine rpm until the

right hand loadmeter indicates a load. Increase engine speed tocruise rpm for 10 seconds.

(3) Shut down left engine. (Rerer to Chapter 71.)(4) While left engine is windmilling downward in speed, observe leftde generator loadmeter. The meter should indicate a rapid decrease

in load toward zero. Upon reaching zero, the meter shouldcontinue reading downward to a minus 0.1 reading, then rapidly

return to zero. If loadmeter does not return to zero, positionthe "LH DC GEN" switch to OFF.

NOTE: The minus 0.1 reading indicates proper operation or thereverse current relay. The loadmeter reading must not

exceed 0.1 in the reverse direction. If it does, or ifthe pointer fails to return to zero immediately after

reading in the reverse direction. The reverse current relayis faulty and should be replaced.

(5) Position "RH DC GEN" switch at OTJ.(6) Shut down right engine. (Refer to Chapter 71.)

(7) Repeat step (4) as applied to right de generator loaameter. Observesame requirements of operation.

(8) Remove electrical power from airplane.(9) Remove test equipment and secure access doors and/or equipment

as necessary.7. Removing Electrical Power Distribution’Relays

A. The removal and installation procedures for the generator control unit,reverse-current relays and the various monitor relays are installedforward of fuselage station 76 or in the electrical equipment rack atfuselage station 150(see figure 24-308-10). To remove relays from

electrical rack assembly, proceed as follows:(1) Place all switches at OFF and remove external power from airplane.

(2) Remove trim panels as necessary to gain access to relay rack.(3) Locate applicable relay on rack (see figure 24-3 OA-l O)

(4) Remove screws securing shelf to rack and slide shelf inboard.(5) Disconnect electrical wiring (non plug-in type) from relay

terminals.

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SAeRErrNeRMAINTENANCE MANUAL

NA-69-420(6) Remove mounting screws from relay and remove relay from shelf.

8. Installing Electrical Power Distribution RelaysA. To install electrical relays on electrical rack shelves, proceed as

follows:(1) Ensure that all electrical power is removed from airplane.Position relay on applicable shelf and secure with attaching

screws (see figure 24-3011-10).(3) Connect electrical wiring (non-plug-in type) to relay terminals.

(Refer to Wiring Diagram Manual.)(4) Position shelf on rack and secure with screws.

(5) Replace trim panels.(6) Perform an operational check-out of system which contains the relay.

8A. Removing and Installing Feeder Protection Relays (Station 150)A. Remove feeder protection as follows:

(1) Place all switches at OFF or airplane parked position and removeexternal power from airplane.

Remove trim panels as necessary to gain access to relay rack.(3) Remove screws that secure the second (from the top) shelf and

slide shelf inboard.(4) Disconnect electrical leads from feeder protection relay. "ag

leads las an aid to proper reinstallation).(5) Remove nut and washer from "GEN" stud of reverse current relay

and lift feeder protection relay from stud.B. Install feeder protection relay as follows:

NOTE: Feeder protection relays (K1049 and K1050) are sensitive differentialcurrent relays that become energized whenever the current

flow though either one of the two large studs exceeds the currentflow through the other stud by 150 to 200 amperes. Since its

operation is based on differential flux magnetic forces, the relaymust be installed in a manner that minimizes the influence of

magnetic flux from outside sources, (such as a nearby bus bar ora large relay).

(1) Ensure that all electrical power is removed from airplane. Checkthat BATTERY and other switches are positioned at OFF.

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SABREtlNERMAINTENANCE: MANUAL

NA-69-420Position feeder protection relay on GEN stud of reverse current

relay on top of bus bar. Secure with washer and nut.(3) Visually check that lower surface of feeder protection relay is

positioned parallel to cover of reverse current relay and thatsides of feeder protection relay are parallel to sides of reverse

current relay.(4) If necessary, loosen GEN stud nut and reposition feeder protection

relay. Tighten nut and repeat step (3).(5) Connect cable leads to feeder protection relay studs.

(6) Connect grounded lead wire to "G" terminal and trip signal wireto "T" terminal.

(7) Reposition relay shelf into rack and secure with screws.(8) Replace trim panels.

(9) Perform an operational check-out of the generator system that con-.s tains this feeder protection relay.

9. Replacement of Battery Temperature SensorsA. To replace battery temperature sensors, proceed as follows:

(1) Remove all electrical power from airplane.(2) Cain access to battery compartment.

(3) Disconnect battery plugs and vent connections.(4) Remove battery(s) from airplane.

(5) Remove cover from battery and disconnect sensor wires to receptacle.(6) Remove cell connector with sensor attached.

B. To replace battery temperature sensor, proceed as follows:(1) Install cell connector with sensor and connect electrical wiring

to receptacle.(2) Install battery(s) in airplane and connect electrical plugs and vent

hoses.(3) Perform operational check-out of battery temperature system.

(4) Check system for security and applicable safeties.(5) Install access doors.

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iNA-69-420MAINTENANCE MANUAL

11. DC Starter/Generator Brush InspectionA. To inspect the starter/generator brushes, proceed as follows:

(1) Remove all electrical power from airplane.(2) Open enginecowling.

(3) Loosen screw securing brush band cover assembly to generator. Lift screw (shank end with

band retainer) from brush band.Do not allowforeign material to enter brush, area.

(4) Remove brush band cover assembly from generator.(5) Inspect brushes (total of eight) as follows:

(a) Check the top of each brush for extension above the brush holders (see Figure 24-30A-7).

(b3 If the top of the brush(es) is even (flush) with the top of the brush holder, continued

inspections at 150-hour intervals is recommended.(c) If the top of the brush recedes to 1/4" below the top surface of the brush holder,

the brushesmust be replaced.

(6) Position brush band cover assembly in place on generator and install band retainer and screw.

Tighten and safety band retainer screw.(7) Check complete installation for security, and close engine cowling.

12. DC Starter/Generatol´• Brush Run-InA. To perform the DC starter/generator brush run-in, proceed as follows:

EQUIPMENT/TOOLSDC power source capable of providing up to 30 volts and 75 amperes. Rheostat

approximately 5.5amperes, 15 ohms.

(1) Place the starter/generator in a padded V-block to run in brushes.(2) Connect the power source posi tive lead to starter/generator terminal B.

Connect powersourcenegative lead to terminal E.

(3) Connect rheostat across terminals A and B.1 (4) Remove brush band cover assembly.

A sudden high-speed startmag cause serious personal injur2/. To control the start, malee sure

the rheostat is ad~usted to the xero resistance point prior to motoring the unit.(5) Run in brushes as follows: Apply power to starter/generator and set rheostat for

a speed of 6000rpm until brushes have a fit of 100 percent ofthe are and at least 75 percent of the

contact area.(6) Blow loose carbon dust from starter/generator; install brush band cover

assembly.

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