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Technical Handbook · 06 of 6

Aviation Technical Glossary

Every term used across this resource hub, defined for practitioners. Search by term, abbreviation or definition, or filter by domain. Where a term means different things under EASA and the FAA, both are given.

Terms
176
Domains
6
Scope
EASA · FAA · commercial & GA
Updated
August 2026

Showing all 176 terms

Airworthiness DirectiveAD
A legally enforceable instrument issued by an airworthiness authority requiring specific action on a defined population of products to address an unsafe condition. Under 14 CFR 39.3 ADs are legally enforceable rules; under EASA they are issued per Part-21 21.A.3B, with compliance required by Part-M M.A.303.
Regulatory
Emergency Airworthiness DirectiveEAD
An AD issued without prior consultation because the unsafe condition requires immediate action. EASA emergency ADs carry an -E suffix; FAA emergency ADs may be issued directly to affected operators.
Regulatory
Proposed Airworthiness DirectivePAD
The EASA consultation draft published for comment before a final AD is issued. The FAA equivalent is a Notice of Proposed Rulemaking.
Regulatory
Notice of Proposed RulemakingNPRM
The FAA's public consultation instrument, published in the Federal Register, preceding a final rule including an AD.
Regulatory
Alternative Method of ComplianceAMOC
An authority-approved alternative to the actions or compliance times in an AD, providing an acceptable level of safety. FAA route under 14 CFR 39.19; the AD names the holding office per 39.21. Granted to a specific applicant and scope.
Regulatory
State of Design
The state that certificated the type and is responsible for the type certificate. It investigates unsafe conditions and issues the originating AD.
Regulatory
State of Registry
The state in which the individual aircraft is registered. The operator's AD obligation arrives through this state, which normally adopts or mirrors State of Design directives.
Regulatory
State of the Operator
The state in which the operator has its principal place of business. Relevant to Article 83 bis transfers.
Regulatory
Article 83 bis83 bis
A 1980 amendment to the Chicago Convention, in force 20 June 1997, permitting the State of Registry to transfer to the State of the Operator its functions under Articles 12, 30, 31 and 32(a) for leased, chartered or interchanged aircraft.
Regulatory
Chicago Convention
The Convention on International Civil Aviation, 1944, establishing the framework of international civil aviation and the ICAO Annexes.
Regulatory
ICAO Annex 8
Airworthiness of Aircraft. Airworthiness directives are the common form of the mandatory continuing airworthiness information referred to in Annex 8.
Regulatory
Regulation (EU) 2018/1139Basic Regulation
The European Union Aviation Safety Agency's founding regulation and the legal basis for the implementing regulations beneath it.
Regulatory
Regulation (EU) No 1321/2014
The continuing airworthiness regulation, recasting Reg. (EC) No 2042/2003. Contains Part-M, Part-145, Part-66, Part-147, Part-T, Part-ML, Part-CAMO and Part-CAO.
Regulatory
Regulation (EU) No 748/2012Part-21
The initial airworthiness and certification regulation. Contains Part-21, including 21.A.3B on airworthiness directives.
Regulatory
Part-MAnnex I
The general continuing airworthiness regime under Reg. (EU) No 1321/2014.
Regulatory
Part-145Annex II
Maintenance organisation approvals under Reg. (EU) No 1321/2014.
Regulatory
Part-66Annex III
Aircraft maintenance licence requirements for certifying staff.
Regulatory
Part-147Annex IV
Maintenance training organisation requirements. Not to be confused with Part-T.
Regulatory
Part-TAnnex Va
Continuing airworthiness of aircraft registered in a third country and dry leased-in by an EU licensed air carrier where oversight has not been delegated to a Member State. Not 'training'.
Regulatory
Part-MLAnnex Vb
Proportionate continuing airworthiness rules for light aircraft, introduced by Reg. (EU) 2019/1383 and applicable from 24 March 2020.
Regulatory
Part-CAMOAnnex Vc
The standalone approval regime for continuing airworthiness management organisations, replacing Part-M Subpart G. Its principal addition is safety management system principles.
Regulatory
Part-CAOAnnex Vd
Combined Airworthiness Organisation requirements — CAMO and/or maintenance functions in one approval, limited to non-complex aircraft not used by a licensed air carrier.
Regulatory
Part-IS
Information security management requirements introduced by Reg. (EU) 2023/203, reaching into continuing airworthiness and other domains.
Regulatory
M.A.201
Part-M point allocating responsibility for continuing airworthiness between owner, lessee, operator, maintenance performer and pilot-in-command.
Regulatory
M.A.301
Part-M point listing the continuing airworthiness tasks, from pre-flight inspection through AD accomplishment to maintenance check flights.
Regulatory
M.A.302
Part-M point requiring an aircraft maintenance programme approved by the competent authority, or indirectly approved via the CAME where a CAMO or CAO manages the aircraft.
Regulatory
M.A.303
Part-M point on airworthiness directives: any applicable AD must be carried out within its requirements unless otherwise specified by the Agency.
Regulatory
M.A.305
Part-M point requiring the aircraft continuing airworthiness record system, including the retention periods at M.A.305(e). Note: retention moved from M.A.305(h) in the pre-2019 structure.
Regulatory
M.A.306
Part-M point requiring an operator's technical log system for commercial air transport, commercial specialised operations and commercial ATO or DTO operations.
Regulatory
M.A.307
Part-M point on transfer of records. Paragraph (c) states that retention periods continue to apply to the new owner, operator, CAMO or CAO — transfer does not reset the clock.
Regulatory
M.A.901
Part-M point governing the airworthiness review and the issue and extension of the Airworthiness Review Certificate.
Regulatory
14 CFR Part 39
The FAA's airworthiness directives rule. Sections include 39.3 (definition), 39.5 (when issued), 39.7 (violation), 39.15 (applies even if changed), 39.19 (AMOC) and 39.23 (special flight permit).
Regulatory
14 CFR 43.9
Content, form and disposition of maintenance, preventive maintenance, rebuilding and alteration records. Sets what a maintenance entry must contain.
Regulatory
14 CFR 43.11
Content, form and disposition of records for inspections under Parts 91 and 125 and certain Part 135 provisions, including the prescribed airworthy or unairworthy certification statement.
Regulatory
14 CFR 91.409
FAA inspection requirements: annual, 100-hour, progressive inspection, and the four selectable inspection programme options for large and turbine-powered aircraft.
Regulatory
14 CFR 91.417
FAA maintenance records rule, splitting records into work records (a)(1), retained one year or until superseded, and status records (a)(2), retained and transferred with the aircraft.
Regulatory
14 CFR 91.419
FAA rule requiring transfer of specified maintenance records to the purchaser at the time of sale of a US-registered aircraft.
Regulatory
Special flight permitFerry permit
Authorisation to fly an aircraft that does not currently meet applicable airworthiness requirements, for example to reach a repair facility. Under 14 CFR 39.23 available unless the AD prohibits it.
Regulatory
Unsafe condition
The finding that triggers an AD: a condition existing in a product which is likely to exist or develop in other products of the same type design.
Regulatory
Type CertificateTC
The design approval for an aircraft, engine or propeller type, issued by the State of Design.
Regulatory
Type Certificate Data SheetTCDS
The document defining the certificated configuration of a type — models, variants, engines, limitations. The population an AD addresses is normally expressed against it.
Regulatory
Supplemental Type CertificateSTC
Approval of a major design change to a type-certificated product, held by a party other than the original type certificate holder.
Regulatory
Effectivity
The clause in an AD or service bulletin defining the population to which it applies — models, serial number ranges and exclusions. The exclusions matter more than the inclusions.
Regulatory
Complex motor-powered aircraftCMPA
A category defined in Reg. (EU) 2018/1139 that determines which continuing airworthiness regime applies. Not defined in Reg. 1321/2014 itself.
Regulatory
ELA2
European Light Aircraft category 2, defined in the Part-21 framework under Reg. (EU) No 748/2012. One of the gates for Part-ML applicability.
Regulatory
Competent authority
The national aviation authority responsible for oversight of a given organisation or aircraft in the European system.
Regulatory
Dynamic Regulatory SystemDRS
The FAA's consolidated repository for regulatory and guidance documents, including airworthiness directives.
Regulatory
Federal Register
The US government's official journal. FAA ADs are published there as amendments to 14 CFR 39.13.
Regulatory
Continuing Airworthiness Management OrganisationCAMO
An organisation approved under Part-CAMO to manage continuing airworthiness on behalf of an owner or operator. Does not perform maintenance unless separately approved.
Organisations & roles
Combined Airworthiness OrganisationCAO
An organisation approved under Part-CAO to perform CAMO activities, maintenance activities or both, limited to non-complex aircraft not used by a licensed air carrier. Certificate: EASA Form 3-CAO.
Organisations & roles
Accountable managerAM
The person with corporate authority for ensuring continuing airworthiness activities can be financed and carried out. Establishes the safety policy, nominates key personnel and carries direct safety accountability.
Organisations & roles
Nominated personPost-holder
The individual responsible for ensuring regulatory compliance of a defined function — for continuing airworthiness, the CAM or equivalent.
Organisations & roles
Compliance monitoring managerCMM
Manages the compliance monitoring function within a CAMO. Must be independent of the functions being monitored.
Organisations & roles
Safety managerSM
Develops and maintains safety management processes and facilitates hazard identification and risk management. The role introduced by Part-CAMO that did not exist under Subpart G.
Organisations & roles
Continuing Airworthiness ManagerCAM
Common title for the nominated person responsible for continuing airworthiness within an operator or CAMO.
Organisations & roles
Airworthiness review staffARS
Appropriately qualified personnel within an organisation holding the airworthiness review privilege, permitted to perform reviews and issue or extend an ARC.
Organisations & roles
Certifying staff
Personnel licensed under Part-66 and authorised to issue a certificate of release to service.
Organisations & roles
Maintenance Repair and Overhaul organisationMRO
A maintenance provider. In the European system, approved under Part-145 or Part-CAO; in the US, a certificated repair station.
Organisations & roles
Air Operator CertificateAOC
The certificate authorising commercial air transport operations. Listing on a licensed air carrier's AOC pushes an aircraft from Part-ML into Part-M.
Organisations & roles
Industry Steering CommitteeISC
The manufacturer-led committee, including engine manufacturers, vendors and operators, that governs the MSG-3 analysis for a new type.
Organisations & roles
Maintenance Working GroupMWG
A specialist group appointed by the ISC to perform MSG-3 analysis in one of four areas: systems and powerplant, structures, zonal, and lightning/HIRF.
Organisations & roles
Maintenance Review BoardMRB
The regulatory authority body that approves the Maintenance Review Board Report for a new type.
Organisations & roles
Airlines for AmericaA4A
Formerly the Air Transport Association (ATA). Develops and maintains the MSG-3 methodology.
Organisations & roles
Approved Training OrganisationATO
A flight training organisation approved under the European rules. Commercial ATO activity affects which continuing airworthiness regime applies.
Organisations & roles
Declared Training OrganisationDTO
A training organisation operating under a declaration rather than an approval.
Organisations & roles
Design Approval HolderDAH
The holder of a type certificate, STC or other design approval, responsible for issuing instructions for continued airworthiness.
Organisations & roles
Production Approval HolderPAH
The holder of a production approval, within whose quality system an 8130-3 airworthiness approval for new production is issued.
Organisations & roles
Maintenance Steering Group 3MSG-3
The task-oriented, top-down analysis methodology maintained by A4A for developing initial scheduled maintenance tasks and intervals. Replaced the process-oriented, bottom-up MSG-2.
Maintenance
Maintenance Significant ItemMSI
An item selected for MSG-3 analysis on the basis of the consequences of its functional failure.
Maintenance
Failure Effect CategoryFEC
MSG-3 classification 5 to 9: evident safety, evident operational, evident economic, hidden safety, hidden non-safety. A task is required for categories 5 and 8, desirable for 6, 7 and 9.
Maintenance
Maintenance Review Board ReportMRBR
The authority-approved minimum scheduled tasking and interval requirements for a type. Explicitly not an operator maintenance programme.
Maintenance
Maintenance Planning DocumentMPD
The manufacturer's planning document. A superset of the MRBR, adding Certification Maintenance Requirements, Airworthiness Limitations and manufacturer recommendations.
Maintenance
Aircraft Maintenance ProgrammeAMP
The operator's customised, authority-approved maintenance programme derived from the MPD. Called OAMP in US usage.
Maintenance
Continuous Airworthiness Maintenance ProgramCAMP
The FAA Part 121 or 135 operator's maintenance programme, referenced in its operations specifications.
Maintenance
Certification Maintenance RequirementCMR
A task required to substantiate the certification safety analysis. Mandatory; changeable only with authority permission.
Maintenance
Airworthiness Limitations SectionALS
The section of the ICA carrying mandatory life limits and inspections arising from the certification basis. Individual entries are Airworthiness Limitation Items.
Maintenance
Instructions for Continued AirworthinessICA
The maintenance instructions a design approval holder must produce for a type or modification.
Maintenance
A check
A light scheduled check. Current narrowbody intervals are around 750 flight hours for the A320 family and 1,000 for the 737NG. Older sources quoting 400 to 600 flight hours are superseded.
Maintenance
B check
A legacy intermediate check. Effectively extinct on modern types — its content has been absorbed into expanded A checks, and it appears in neither the A320 nor 737NG maintenance structure.
Maintenance
C check
A base check requiring the aircraft out of service. A320 family interval 7,500 FH / 5,000 FC / 24 months, whichever first; 737NG typically 24 to 36 months.
Maintenance
D check
Traditional term for the heavy structural check. Now largely colloquial: current-production types deliver heavy work as calendar escalation packages on a base check, and Airbus removed letter checks from the A350 MPD entirely.
Maintenance
Heavy Maintenance VisitHMV
The current term for the heavy structural visit formerly described as a D check.
Maintenance
Base maintenance
Work requiring the aircraft to be withdrawn from service into a hangar for an extended period. Contrasted with line maintenance.
Maintenance
Line maintenance
Work performed while the aircraft remains in service — turnrounds, transit and daily checks, defect rectification and light scheduled tasks.
Maintenance
Escalation package6YE / 12YE
A calendar-driven group of structural tasks attached to a base check — the six-year and twelve-year packages on the A320 family being the common examples.
Maintenance
Block maintenance
Packaging philosophy grouping tasks into a few large letter checks. Simple to plan; long downtime and spiky manpower demand.
Maintenance
Phased maintenanceEqualised, segmented
Packaging philosophy distributing the same task content across many short visits, improving availability and smoothing labour at comparable total man-hours.
Maintenance
Non-routineNRC
Work arising from findings during a check, as opposed to planned routine content. The non-routine ratio rises from about 0.12 at an early C check to 0.80 on a high-age airframe.
Maintenance
General Visual InspectionGVI
The least intrusive MSG-3 inspection level — a visual examination of an area, installation or assembly.
Maintenance
Detailed InspectionDET
An intensive MSG-3 visual examination of a specific item, normally requiring good lighting and possibly cleaning or access provisions.
Maintenance
Special Detailed InspectionSDI
The most intensive MSG-3 inspection level, requiring specialised techniques such as NDT, and possibly disassembly.
Maintenance
Functional CheckFNC
A quantitative MSG-3 check comparing a measured value against an established standard.
Maintenance
Operational CheckOPC
A failure-finding MSG-3 task confirming an item fulfils its intended purpose. Applied only to hidden failures.
Maintenance
RestorationRST
An MSG-3 task returning an item to a specified standard at or before an age limit, from cleaning up to full overhaul.
Maintenance
DiscardDIS
An MSG-3 task removing an item from service at a life limit where restoration is not feasible.
Maintenance
Service BulletinSB
A manufacturer-issued instruction for a modification, inspection or repair. Not mandatory in itself, but an AD may make a specific revision mandatory.
Maintenance
Service LetterSL
A manufacturer communication of a recommendation or information, of lower status than a service bulletin.
Maintenance
Aircraft Maintenance ManualAMM
The manufacturer's manual containing the procedures used to carry out maintenance tasks.
Maintenance
Illustrated Parts CatalogueIPC
The manufacturer's parts identification document.
Maintenance
Component Maintenance ManualCMM
The maintenance procedures for a specific component, usually issued by its manufacturer.
Maintenance
Structural Repair ManualSRM
The manual defining allowable damage limits and approved repairs for the airframe structure. Redelivery conditions on dents and corrosion reference it.
Maintenance
Minimum Equipment ListMEL
The operator's approved list of items that may be inoperative for despatch, under stated conditions and time limits.
Maintenance
Configuration Deviation ListCDL
The list of external parts that may be missing for despatch, with associated performance penalties.
Maintenance
Minimum Inspection ProgrammeMIP
The Part-ML fallback programme: annual or 100-hour inspection, whichever comes first, with defined tolerances.
Maintenance
Progressive inspection
An FAA inspection route under 14 CFR 91.409(d) distributing inspection content across the year, requiring a complete inspection within each 12 calendar months.
Maintenance
Annual inspection
The FAA requirement under 14 CFR 91.409(a) for an inspection within the preceding 12 calendar months.
Maintenance
100-hour inspection
The FAA requirement under 14 CFR 91.409(b) for aircraft carrying persons for hire or used for flight instruction for hire. May be exceeded by not more than 10 hours to reach an inspection facility.
Maintenance
Pre-flight inspection
The inspection before flight, the responsibility of the pilot-in-command or, for licensed air carriers, the operator.
Maintenance
Maintenance check flightMCF
A flight performed to verify the functioning of systems after maintenance, listed among the continuing airworthiness tasks in M.A.301.
Maintenance
Reliability programme
The analysis of in-service data used to demonstrate the effectiveness of a maintenance programme and to support interval escalation.
Maintenance
Interval escalation
Extending a task interval on the basis of reliability evidence, with authority approval. Not available for Airworthiness Limitations or CMRs.
Maintenance
Hard timeHT
A maintenance process requiring removal at a fixed limit, regardless of condition.
Maintenance
On conditionOC
A maintenance process in which an item remains in service while inspection or test shows it meets defined criteria.
Maintenance
Condition monitoringCM
A maintenance process relying on analysis of in-service failure data rather than a fixed removal limit.
Maintenance
Certificate of Release to ServiceCRS
The release of maintenance in the European system, certifying that the work was carried out per the applicable requirements.
Records
Technical logTech log
The operator's per-flight record system required by M.A.306, carrying flight information, the current CRS, the current maintenance statement and outstanding deferred defects.
Records
Continuing airworthiness record system
The record system required by M.A.305 covering logbooks, life-limited component records, current status of ADs, modifications, AMP compliance, mass and balance and deferred maintenance.
Records
Back-to-birth traceabilityBTB
Documentation of a part's provenance since first operation — every owner and installation back to manufacture. Standard industry practice imposed contractually by lessors; not a general regulatory requirement of the FAA, EASA or ICAO.
Records
Life-Limited PartLLP
A part with a mandatory life limit that must be discarded rather than restored. Engine LLPs dominate the value at risk in records failures.
Records
Time Since NewTSN
Elapsed operating hours on a part or product since manufacture.
Records
Cycles Since NewCSN
Accumulated cycles on a part or product since manufacture.
Records
Time Since OverhaulTSO
Operating hours since the last overhaul.
Records
Cycles Since OverhaulCSO
Accumulated cycles since the last overhaul.
Records
Total time in serviceTTIS
The cumulative time in service of an airframe, engine, propeller or rotor. A permanent status record under 14 CFR 91.417(a)(2)(i).
Records
Flight hourFH
A unit of elapsed operating time, one of the three clocks against which maintenance and AD compliance times run.
Records
Flight cycleFC
One take-off and landing. The clock that governs fatigue-driven limits and typically binds for short-sector operators.
Records
Dirty fingerprint
Informal term for the physical evidence trail — original signed records demonstrating that work actually took place.
Records
Deferred defect
A defect whose rectification is postponed under the MEL or an approved procedure, recorded in the technical log and the deferred maintenance list.
Records
Discrepancy list
The signed and dated list of unairworthy items a person must give the owner or lessee under 14 CFR 43.11(b) where an aircraft is found not airworthy.
Records
Electronic signature
Per FAA AC 120-78B, a signature that is unique to the signer, authenticated, under sole control, executed with intent, the result of a deliberate action, non-repudiable and permanent, on a document that cannot subsequently be edited.
Records
Records audit
The examination of an aircraft's records for completeness, accuracy and regulatory compliance. In a lease transition it is the most time-consuming phase and the usual cause of delay.
Records
Work pack
The compiled documentation for a maintenance visit — task cards, non-routine cards, parts records and the release. Frequently the source of records gaps when not returned complete.
Records
EASA Form 1
The authorised release certificate for a component in the European system. Equivalent to the FAA 8130-3.
Documents & forms
FAA Form 8130-3
Authorized Release Certificate / Airworthiness Approval Tag. Serves three distinct functions: airworthiness approval of new production, return to service after maintenance, and support of export approval.
Documents & forms
Dual release
A release certificate endorsed under both the FAA and EASA systems, allowing the part to be accepted in either jurisdiction without further documentation.
Documents & forms
FAA Form 337
Major Repair and Alteration record required by 14 CFR 43.9(d). Copies for major alterations form part of the permanent status records that travel with the aircraft.
Documents & forms
EASA Form 15a / 15b / 15cARC forms
Airworthiness Review Certificate forms: 15a issued by the competent authority, 15b by a CAMO or CAO, 15c under Part-ML.
Documents & forms
EASA Form 14
The certificate evidencing a Part-CAMO approval.
Documents & forms
EASA Form 3-CAO
The certificate evidencing a Part-CAO approval.
Documents & forms
Continuing Airworthiness Management ExpositionCAME
The CAMO's controlling document, required by CAMO.A.300, describing how it exercises its privileges — including any indirect AMP approval procedure.
Documents & forms
Airworthiness Review CertificateARC
The periodic certificate confirming continuing airworthiness has been managed. Valid one year, extendable at most twice by one year each where the aircraft remains in a controlled environment.
Documents & forms
Controlled environment
An aircraft continuously managed by a single CAMO or CAO and maintained by organisations approved under Part-145, Part-M Subpart F or Part-CAO over the previous 12 months. The condition for ARC extension.
Documents & forms
Certificate of AirworthinessCofA
The certificate evidencing that an individual aircraft conforms to its approved type design and is in condition for safe operation. Does not itself expire in the way an ARC does.
Documents & forms
Advisory CircularAC
FAA guidance describing an acceptable means, but not the only means, of compliance. AC 120-78B covers electronic records; AC 43-9D supersedes AC 43-9C on maintenance records.
Documents & forms
Operations specificationsOpSpecs
The document defining the authorisations, limitations and procedures under which a US certificate holder operates.
Documents & forms
Task card
The executable instruction for a scheduled or non-routine task, referencing the AMM procedure.
Documents & forms
Operating lease
A lease under which the lessor retains the residual value risk and the aircraft returns at the end of the term, subject to redelivery conditions.
Leasing & finance
Finance lease
A lease structured so that substantially all the risks and rewards of ownership pass to the lessee, typically with a purchase option.
Leasing & finance
Dry lease
A lease of the aircraft without crew. The lessee operates under its own AOC, which is the trigger for Part-T where the aircraft is third-country registered.
Leasing & finance
Wet leaseACMI
A lease including aircraft, crew, maintenance and insurance, operated under the lessor's AOC.
Leasing & finance
Redelivery conditionsReturn conditions
The contractual standard to which an aircraft must be returned at lease expiry, covering physical, records, performance and certification categories.
Leasing & finance
Mirror-in / mirror-out
A drafting philosophy requiring the aircraft to be returned in materially the condition in which it was delivered.
Leasing & finance
Redelivery check
The maintenance visit performed to bring the aircraft to the condition the outgoing lease requires. Distinct from a bridging check.
Leasing & finance
Bridging check
The work package required to bring an aircraft onto the incoming operator's approved maintenance programme, derived from a comparative task analysis.
Leasing & finance
Bridging document
The analysis establishing current maintenance status, defining the incoming programme, identifying unique tasks and cross-referencing task numbering.
Leasing & finance
Half-life
The appraisal convention assuming an asset is midway between scheduled maintenance events. The baseline for Base Value and Current Market Value unless otherwise stated.
Leasing & finance
Full-life
Condition assuming 100% life remaining, with major maintenance either completed or compensated for.
Leasing & finance
Maintenance adjustment
The correction applied to a half-life baseline to reach a maintenance-adjusted value for a specific asset, counting airframe checks, landing gear, engine restorations, LLPs and APU.
Leasing & finance
Base ValueBV
An appraiser's opinion of the underlying economic value of an aircraft in a balanced market, conventionally quoted half-life.
Leasing & finance
Current Market ValueCMV
An appraiser's opinion of the most likely trading price in the current market, conventionally quoted half-life.
Leasing & finance
Maintenance reservesSupplemental rent
Payments made by a lessee against future major maintenance events, drawn down when the work is performed. A recurring source of dispute at redelivery.
Leasing & finance
Exhaust Gas Temperature MarginEGTM
The headroom before an engine reaches its temperature limit. A primary indicator of remaining on-wing life and a common redelivery condition.
Leasing & finance
Engine Flight CyclesEFC
Cycles accumulated by an engine. Lessors typically look for 3,000 to 5,000 EFC remaining on-wing for a narrowbody engine at redelivery.
Leasing & finance
Limiter
The life-limited part with the least remaining life, determining when an engine must come off wing.
Leasing & finance
Performance restorationPR
The engine shop visit that restores performance, typically the largest single maintenance event in an aircraft's cost profile.
Leasing & finance
Cape Town ConventionCTC
The Convention on International Interests in Mobile Equipment and its Aircraft Protocol, concluded 16 November 2001, creating internationally recognised interests via the International Registry.
Leasing & finance
Aircraft Protocol
The Protocol on Matters Specific to Aircraft Equipment, read together with the Cape Town Convention as a single instrument. Article XIII establishes the IDERA.
Leasing & finance
International RegistryIR
The electronic registry established under the Cape Town Convention for recording international interests in aircraft objects.
Leasing & finance
IDERA
Irrevocable De-Registration and Export Request Authorisation. Issued by the debtor in favour of an authorised party, who becomes the only party entitled to deregister and export the aircraft. Irrevocable by the debtor.
Leasing & finance
Alternative A
An insolvency regime option under the Cape Town Convention that a contracting state may declare, with defined waiting periods and registry response obligations.
Leasing & finance
Cape Town Discount
The reduction in OECD export credit premium — approximately 10% — available to airlines in qualifying Cape Town states.
Leasing & finance
Pre-purchase inspectionPPI
The technical and records inspection performed before an aircraft sale, and one of the trigger events for records reconciliation.
Leasing & finance
Transition
The end-to-end process of moving an aircraft from one operator or owner to another, encompassing redelivery, records, bridging and re-registration.
Leasing & finance
Penalty rentHoldover rent
Rent continuing at an increased rate — often a multiple of the normal rate — where an aircraft is not redelivered on time and in the required condition.
Leasing & finance
Fair wear and tear
A contractual standard describing acceptable deterioration. Best suited to interior condition, and the source of most redelivery disputes because it is inherently interpretive.
Leasing & finance
Joint condition survey
An inspection performed by lessor and lessee together, ideally early in the transition, establishing an agreed baseline with photographic evidence.
Leasing & finance

More in this handbook

Technical references for continuing-airworthiness teams, kept current against the consolidated regulation.

Airworthiness DirectivesLegal basis, how applicability is really determined, compliance times, AMOCs, supersession and records.Maintenance ChecksMSG-3, the MRBR–MPD–AMP chain, and what the letter checks actually mean now.CAMO & Part-MRegulation (EU) No 1321/2014, Part-CAMO, the ARC, and who is accountable for what.Technical RecordsWhat must be kept, for how long, and how a records gap destroys asset value.Lease TransitionsRedelivery conditions, back-to-birth, bridging, Article 83 bis and the IDERA.

Editorial note. This page is an educational technical reference and is not a substitute for the regulation, the manufacturer’s documentation or the contract. Regulatory references are given to help you find the primary source: verify against the current consolidated texts — EASA Easy Access Rules for Regulation (EU) No 1321/2014, Regulation (EU) No 748/2012, and 14 CFR — before relying on any point reference. Nothing here constitutes an airworthiness determination, a legal opinion or contractual advice for any individual aircraft. See our disclaimer. Last reviewed 2026-08-29.