Component Maintenance, Lecture notes of Aerospace Engineering

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Component shop

organization and processes

Quentin Souleau

Goals of the course

Learn about the maintenance of aeronautical Components

Discover the organization of a Part 145 shop

Understand the mechanisms of growth and profitability in the MROs

1. Essential definitions

1.1. Maintenance levels

1.2. Reminders on EASA Parts

1.3. Key players in the component industry

1.4. Component, LRU and SRU

1.5. Rotable / expendable

1.6. Serviceable, unserviceable units

1.7. Traceability: Part Number & Serial Number

1.8. Work scopes & repair levels

1.9. ATA org & ATA 100 Chapters

1.10. ATA iSpec 2200

1.11. Form, Fit, Function

1.12. Interchangeability, mixability

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1.1. Maintenance levels

3 levels of maintenance, based on: complexity, tasks performed, manpower needed etc.

Line maintenance / Organizational Maintenance (O-level) Intermediate maintenance (I-level) Shop maintenance level / Depot level (D-level)

Intermediate maintenance (I-level)

Heavier maintenance operations with test of components, mass removals

and replacement of components, heavier inspections. Periodical checks

(example : A, B, C, D checks). Generally on-wing.

Shop maintenance level / Depot level (D-level)

Maintenance in industrial-type facilities ; longer operations on specific parts of the

Aircraft : structure, engines, components. Test, repair and overhauls performed.

Modifications of equipment. Off-wing.

1.3. Key players in the component industry

OAM: Original Aircraft Manufacturer.

Boeing, Airbus, Embraer, ATR, Bombardier, Cessna etc.

OEM: Original Equipment Manufacturer.

Thalès, Safran, Honeywell, Hamilton etc.

MRO: Maintenance Repair Organisation or Maintenance, Repair & Operations. Designate

the generic aeronautical maintenance business or an entity in charge of maintenance. Independent MROs : Sabena Technics, Haeco, SR Technics etc.

Airline MRO: MRO attached to an Airline

Air France KLM Engineering & Maintenance, Lufthansa Technik, SIA Engineering etc.

Broker: Spare Part and Component dealer. Buy, sale, loan of equipments.

Avtrade, AAR, Touchdown Aviation etc.

1.4. Component, LRU and SRU Component: Generic term for aeronautical parts fitted on aircraft that are not structure or engine items. Also used in this class : unit, part, equipment. LRU: Line Replaceable Unit. Unit generally removed from the Aircraft during light or heavy maintenance. Can especially be removed during short stops between flights. Example: Slide, Seat, toilets, VHF, Flight Data Recorder, Multi Control Display Unit, actuator etc. The number of instances of a LRU on an aircraft is called the Quantity Per Aicraft (QPA). Several identical LRUs of the same aircraft form a chipset. Example : QPA (VHF) = 3. SRU: Shop Replaceable Unit. Unit found inside an LRU, removed only in shop. Example: electronic board, slide oxygen bottle, toilet bowl etc. There is a relation between LRU, SRU and consumable parts called Next Higher Assembly (NHA) and Next Lower Assembly (NLA). The NHA of a SRU is generally a LRU. The NLA of a SRU is generally a consumable part.

Example of SRU 13

Electronic board

1.5. Rotable / expendable

Rotable: Rotable units are repairable, serialized and tracked on aircraft. Any unit

repairable may be called rotable: it cycles between On-wing service, Off-wing repair

and storage.

Example : most LRUs and SRUs

Expendable/consumable: a unit discarded every time it is failing, is called

expendable or consumable.

Example : screw, bolt, resistor, capacitor, lights etc.

1.7. Traceability: Part Number & Serial Number

Traceability of all aeronautical parts is mandatory. Rotables and consumables are all identified through: Part Number (P/N) : Unique identifier of a specific part design. P/N is set at the design of the part. Serial Number (S/N) : Unique identifier of a specific instantiation of that part design. S/N can be common between different part numbers. S/N is set at the fabrication of the part. Manufacturer, P/N and S/N can be found on the label of the component.

1.8. Work scopes & repair levels Inspection: Determine global state of the equipment. Can be visual, destructive, borescope, etc. Test: Action of testing an equipment to determine faults. Repair: Action of repairing faults found. Overhaul: Action of restoring potential of an equipment by performing major, preventive repairs. Modification : Action of accomplishing an AD or VSB task on a component. Similar to the Maintenance level defined in Chapter 1.1, repair levels can be defined on three levels: Level 1 : inspection Level 2 : SRU replacement Level 3 : expendables replacement, repair to the smallest component level. An aeronautical maintenance shop can repair some SRUs of an LRU at level 3 and others at level 2 only.