[GLO]Glossary
The vocabulary of aircraft condition.
Terms that appear in leases, maintenance records and inspection reports, defined in plain language.
[GLO.1]Terms
30 terms, A to Z.
- Airworthiness directive (AD)
- A mandatory instruction from an aviation authority to correct an unsafe condition in an aircraft, engine or component.
- APU
- Auxiliary power unit. A small turbine, usually in the tail, that supplies electrical power and air on the ground.
- Back to birth trace
- An unbroken documented history of a part from its manufacture to the present, covering every installation, removal and shop visit.
- Borescope inspection
- An internal inspection of an engine or structure using a camera on a probe, without disassembly.
- Bridging
- The process of moving an aircraft from one maintenance program to another without missing or duplicating tasks.
- C check
- A heavy scheduled inspection, typically every 18 to 36 months depending on the aircraft and program.
- Cycle
- One takeoff and landing. Many structural and engine limits are counted in cycles as well as hours.
- DAR
- Designated Airworthiness Representative. A private individual authorized by the FAA to perform certain certification functions.
- Deferred defect
- A known defect permitted to remain open for a limited time under the minimum equipment list or approved data.
- Dirty fingerprint record
- The original signed task card or work record, as opposed to a summary prepared from it.
- EASA Form 1
- The European authorized release certificate for a new or maintained part.
- Export certificate of airworthiness
- A statement by the exporting authority that an aircraft conforms to the importing country's requirements.
- FAA Form 8130-3
- The United States authorized release certificate, or airworthiness approval tag, for a part.
- Hard time component
- A component that must be removed for overhaul or scrap at a fixed interval, whatever its condition.
- Heavy check
- A major scheduled maintenance visit in which the aircraft is opened up for structural and systems inspection.
- Life limited part (LLP)
- A part with a mandatory retirement life in hours or cycles, after which it cannot be used.
- Maintenance planning document (MPD)
- The manufacturer's listing of scheduled maintenance tasks and intervals for an aircraft type.
- Maintenance reserves
- Payments made by a lessee during the lease toward the cost of future major maintenance.
- Major repair
- A repair that could appreciably affect strength, performance or airworthiness and so requires approved data.
- MEL
- Minimum equipment list. The approved list of equipment that may be inoperative for flight, with conditions.
- MRO
- Maintenance, repair and overhaul. Also used for the organizations that perform it.
- Non-routine card
- A task card raised during a check for a defect found, as opposed to a planned task.
- On condition
- A maintenance approach in which a component stays in service until inspection or monitoring shows it should be removed.
- Part-out
- The disassembly of an aircraft at the end of its life so that its components can be sold.
- Power assurance run
- An engine ground run that demonstrates the engine produces rated power with acceptable margin.
- Redelivery conditions
- The condition in which a lease requires the aircraft and its records to be returned.
- Service bulletin (SB)
- A manufacturer's recommended inspection or modification. Mandatory only if made so by an airworthiness directive or a contract.
- Special flight permit
- Permission to fly an aircraft that does not meet all airworthiness requirements but is safe for a specific flight. Often called a ferry permit.
- Structural repair manual (SRM)
- The manufacturer's manual of allowable damage limits and approved structural repairs.
- Supplemental type certificate (STC)
- An approval for a major change to an aircraft's type design, such as a freighter conversion.
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