Development of Maintenance Programs

Embry-Riddle Aeronautical University

Chapter 2

February 5

•1914 — Lt. J.C. Morrow became 24th and last flier to qualify as “Military Aviator.”

THIS DAY IN AVIATIONTHIS DAY IN AVIATION

February 5

•1919 — The first regular, daily passenger service in the world is launched at Berlin's city airfield. A German airline operates the new service on route from Berlin to Weimar via Leipzig.

THIS DAY IN AVIATIONTHIS DAY IN AVIATION

February 5

•1929 — Frank Hawks and Oscar Grubb land their Lockheed “Air Express” in New York after a record flight of 18 hours 20 minutes from Los Angeles.

THIS DAY IN AVIATIONTHIS DAY IN AVIATION

February 5

•1949 — An Eastern Air Lines Lockheed “Constellation” lands at LaGuardia, New York, at the end of a flight of 6 hours 18 minutes from Los Angeles, a coast-to-coast record for transport aircraft.

THIS DAY IN AVIATIONTHIS DAY IN AVIATION

February 5

•1951 — The United States and Canada announce the establishment of the Distant Early Warning (DEW), the air defense system that uses more than 30 radar stations located across the northern portion of the continent.

THIS DAY IN AVIATIONTHIS DAY IN AVIATION

February 5

•1962 — A Sikorsky HSS-2 “Sea King” of the United States Navy sets a world helicopter speed record of 210.6 mph, in the course of a flight between Milford and New Haven, Connecticut.

THIS DAY IN AVIATIONTHIS DAY IN AVIATION

Questions / CommentsQuestions / Comments

Development of Maintenance ProgramsDevelopment of Maintenance Programs

Embry-Riddle Aeronautical University

Chapter 2

Before the Wright Flyer…

Development of Maintenance Development of Maintenance ProgramsPrograms

Development of Maintenance Development of Maintenance ProgramsPrograms

Introduction Maintenance Steering Group (MSG)

Approach Process-Oriented Maintenance Task-Oriented Maintenance Maintenance Program Documents Maintenance Intervals Defined Changing Basic Maintenance Intervals Summary

IntroductionIntroductionIntroductionIntroduction Two basic approaches to Maintenance

Process-oriented Task-oriented Difference between two:

is the attitude toward maintenance actions the manner in which actions are assigned to

components and systems

Process-oriented Approach Hard time (HT) On-condition (OC) Condition monitoring (CM)

Introduction

Process-oriented Approach HT and OC are for components

or systems that have definite life limits or detectable wear out periods (Table 1.1 – A, B, C) – pg 10

CM items are operated to failure and failure rates are tracked to aid in future prediction or failure rate prevention (Table 1.1 – D, E, F)

Introduction

Task-oriented Approach Uses predetermined

maintenance tasks to avoid in-service failures

Redundancy and reliability programs utilized

Introduction

Maintenance Steering Group Maintenance Steering Group Approach (MSG)Approach (MSG)

Maintenance Steering Group Maintenance Steering Group Approach (MSG)Approach (MSG)

Began in 1968 (747) with reps from Boeing’s design and maintenance groups, from the suppliers, airlines who desired to purchase aircraft and the FAA.

6 working groups – structures, mechanical systems, engine and auxiliary power plant (APU), electrical and avionics systems, flight controls and hydraulics, and zonal.

Used “bottom-up” review to determine which process to use HT, OC or CM.

Maintenance Steering Group Maintenance Steering Group Approach (MSG)Approach (MSG)

Maintenance Steering Group Maintenance Steering Group Approach (MSG)Approach (MSG)

MSG-2 used: (pg. 17) Systems and components; structures; and

engines Step 1 identify the maintenance or

structure items requiring analysis Step 2 identify the functions and failure

modes associated with the item and the effect of a failure

Step 3 identify those tasks which may have potential effectiveness

Step 4 assess the applicability of those tasks and select those deemed necessary

Step 5 for structures only, evaluate initial sampling thresholds

MSG-2 no longer used

Process-Oriented MaintenanceProcess-Oriented MaintenanceProcess-Oriented MaintenanceProcess-Oriented Maintenance Hard Time (HT)

is the removal of an item at a predetermined interval (hrs, cycles, calendar time)

On-condition (OC) item will be checked at specific intervals (hrs,

cycles, or calendar time) Condition Monitoring (CM)

monitors failure rates, removal rates etc. to facilitate maintenance planning

Hard Time (HT)Hard Time (HT)Hard Time (HT)Hard Time (HT) Requires item be removed and either completely

overhauled, partially overhauled (restored), or discarded before exceeding the specified interval

(calendar time, engine change, cycles, flight hours, specified flights – over water etc..)

Items that can have an adverse effect on safety but no maintenance check for that condition

Rubber seals, bushing etc.. Structural inspection, landing gear overhaul, and life

limited engine parts, mechanical actuators, hydraulic pumps and motors, electric motors and generators

Can be OC as long as not safety related…

On-condition (OC)On-condition (OC)On-condition (OC)On-condition (OC) Requires item be periodically inspected or

tested to determine if item can continue in service – overhaul, restore or replace

On-condition limited to continued airworthiness by measurements or tests without doing a tear-down inspection

Examples – tire tread and brake linings, scheduled borescope inspections of engines, engine oil analysis

Other include – Brake wear indicator pins Control cables (measure for diameter, tension,

and broken strands) Linkages, control rods, pulleys etc (measure for

wear, end or side play, or backlash

Condition Monitoring (CM)Condition Monitoring (CM)Condition Monitoring (CM)Condition Monitoring (CM) Involves the monitoring of the failure rates,

removals, etc. of individual components or systems that do not have a definite lifetime or noticeable wear out period

CM components are operated until failure occurs – unscheduled maintenance

FAA states regarding CM: Item has no direct, adverse effect on safety Must not have any “hidden function” (not evident to crew)

that could effect safety Must be in condition monitoring or reliability program Avionics and electronic components

Basic elements include – data on unscheduled removals, maintenance log entries, on-board data systems, shop findings etc. – can be used to adjust HT and OC intervals

Only monitors failure not the condition of items

Task-oriented (MSG-3)Task-oriented (MSG-3)Task-oriented (MSG-3)Task-oriented (MSG-3) “Top-down” approach or “consequence of

failure” – safety driven Used to identify suitable scheduled

maintenance tasks to prevent failures and maintain the inherent reliability of the system

Three categories: Airframe systems tasks Structural item tasks Zonal tasks

Maintenance Tasks for Airframe Maintenance Tasks for Airframe SystemsSystems

Maintenance Tasks for Airframe Maintenance Tasks for Airframe SystemsSystems

Lubrication Servicing Inspection Functional Check Operational Check Visual Check Restoration Discard

Maintenance Tasks for Structural Maintenance Tasks for Structural ItemsItems

Maintenance Tasks for Structural Maintenance Tasks for Structural ItemsItems

Environmental Deterioration Climate or environment – may be time dependent

Accidental Damage Result of human error or impact with an object

Fatigue Damage Crack or cracks due to loading or stress

Inspections for Deterioration of Inspections for Deterioration of Structural ItemsStructural Items

Inspections for Deterioration of Inspections for Deterioration of Structural ItemsStructural Items

General Visual Inspection Visual exam that will detect obvious conditions or

discrepancies Detailed Inspection

Use of inspection aids, (i.e. mirrors, hand lenses) may require surface cleaning and detailed access

Special Detailed Inspection Use of Nondestructive inspection (NDI): dye

penetrant, high-powered magnification, magnetic particle, eddy current

Zonal Maintenance TasksZonal Maintenance TasksZonal Maintenance TasksZonal Maintenance Tasks

Ensures all systems, components, and installations within a specified zone receive adequate screening, security of installation and general condition

Look, listen, and feel test General visual inspection Detailed visual inspection

MSG-3MSG-3MSG-3MSG-3

Failure is assigned safety and economic whether it is an evident or hidden failure

Fig. 2-2, Pg. 25 – Level One analysis

Fig 2-3, Pgs. 26, 27 – Level Two analysis

Maintenance Program DocumentsMaintenance Program DocumentsMaintenance Program DocumentsMaintenance Program Documents

Maintenance Review Board Report (MRBR) Contains the initial scheduled maintenance program

for US certificated operators

Includes the systems and power plant maintenance program, the structural inspection program, and the zonal inspection program

Also includes aircraft zone diagrams, a glossary, and list of abbreviations and acronyms

Maintenance Program DocumentsMaintenance Program DocumentsMaintenance Program DocumentsMaintenance Program Documents Maintenance Planning Document (MPD)

Contains all the maintenance task information from the MRBR report plus additional tasks by the airframe manufacturer

Sorts tasks in various ways: letter check, hrs, cycles and calendar time

Includes diagrams showing locations and numbering of access doors and panels, aircraft dimensions, planning for maintenance checks – to include man-hour requirements

• The Monthly Maintenance Plan is used to identify the projected maintenance work load such as inspections, receipts/transfers, technical directive compliance, etc.

• The Monthly Maintenance Plan

provides requirement data for aircraft maintenance, SE material, manpower and training.

• The Monthly Maintenance Plan is under the cognizance of the MO.

Monthly Maintenance Plan

Monthly Maintenance Plan 1. Projected known operational commitments,

including number of flights, flight hours, and utilization goals. 2. Dates of scheduled inspections.

3. Date of receipt or transfer of aircraft.

4. Precision Measuring Equipment (PME) calibration requirements. 5. Schedule of technical training. 6. Forced removal items.

7. Technical Directive Compliance (TDC) requirements. 8. Schedule of personnel for ejection seat safety check out 9. Schedule of pre-inspection meetings. 10. Current list of QA personnel 11. Dates of scheduled SE inspections.

12. Scheduled nondestructive inspection (NDI) requirements

Maintenance IntervalsMaintenance Intervals Maintenance IntervalsMaintenance Intervals

Most intervals are standard but airlines can create own intervals as long as the integrity of the original task is maintained or receive FAA approval

Transit Check – pre-flight and turn Visual, open/loose panels, fluid leaks

48 hour Checks – “daily” Wheels, brakes, fluid levels, hydraulic fluid

Hourly limit Checks – (100, 200, 250 etc.) Engines, flight control systems

Maintenance IntervalsMaintenance Intervals Maintenance IntervalsMaintenance Intervals

Operating cycle limit Checks Tires, brakes, landing gear, airframe structures

Letter Checks – (A, B, C, and D) Development of 777, MSG-3 eliminated checks

Changing Intervals Hot, humid climates – more CC Dry, desert climates – check for sand and dust As aircraft age intervals for some items may

shorten while others may lengthen

SummarySummarySummarySummary Process-oriented and Task-oriented approaches

HT, OC and CM vs. scheduled, redundancy, and reliability MSG, MSG-2, and MSG-3

Structures, mechanical systems, engine and APU, electrical and avionics, flight controls and hydraulics, zonal

Systems and components; structures; and engines Straightforward logic approach; “How does failure effect

operation?” Maintenance Documents – (MRBR and MPD) Maintenance Intervals

Transit, 48 hr, hourly, cycles, Ltr Checks Changing Intervals

Questions?Questions?Questions?Questions?