Aviation Maintenance Abbreviations & Acronyms

Searchable A–Z reference of 130+ aviation maintenance abbreviations and acronyms.

132 results

Abbreviation	Full Name	Explanation
A&P	Airframe & Powerplant	The two ratings required for FAA aircraft mechanic certification (14 CFR Part 65).
ACARS	Aircraft Communications Addressing and Reporting System	Digital data link for aircraft-ground communications.
ACAS	Airborne Collision Avoidance System	ICAO term for TCAS; onboard system that alerts crew to traffic conflicts.
ACM	Aircraft Component Maintenance	General term for component-level maintenance and repair activities.
AD	Airworthiness Directive	FAA-mandated action required to correct an unsafe condition in an aircraft or component.
ADF	Automatic Direction Finder	Radio navigation instrument that displays bearing to an NDB ground station.
ADL	Allowable Damage Limits	Defined limits within which structural damage is acceptable without repair.
ADS-B	Automatic Dependent Surveillance-Broadcast	Aircraft position broadcast system required by FAA since Jan 2020.
AFMS	Airplane Flight Manual Supplement	Document supplementing the AFM for a specific modification or equipment change.
AGE	Aerospace Ground Equipment	Equipment used on the ground to support aircraft maintenance and servicing.
AHM	Aircraft Health Monitoring	System that monitors aircraft systems in real time and reports anomalies.
AME	Aviation Medical Examiner	FAA-designated physician authorized to conduct airman medical examinations.
AMM	Aircraft Maintenance Manual	The manufacturer's primary maintenance reference document for a specific aircraft type.
AMOC	Alternative Method of Compliance	FAA-approved alternate means of complying with an Airworthiness Directive.
AMOS	Aircraft Maintenance and Operations System	Software platform for managing maintenance records and planning.
AMT	Aircraft Maintenance Technician	FAA-certificated mechanic holding Airframe and/or Powerplant ratings.
AOG	Aircraft on Ground	Status indicating an aircraft is grounded due to a defect, awaiting parts or repair.
APB	Airworthiness Parts Bulletin	Document from an OEM regarding parts that may affect airworthiness.
APU	Auxiliary Power Unit	Small turbine engine providing ground power and bleed air independent of main engines.
ASB	Alert Service Bulletin	Service bulletin requiring prompt attention due to safety significance.
ATA	Air Transport Association	Industry standard numbering system (ATA iSpec 2200) used to organize aircraft maintenance manuals.
ATA 100	ATA 100 Specification	Legacy chapter numbering system for aircraft maintenance manuals (superseded by ATA iSpec 2200).
AWL	Airworthiness Limitation	Mandatory maintenance task defined in the ICA that cannot be deviated from without FAA approval.
BIT	Built-In Test	Self-diagnostic capability built into avionics or electronic systems to detect faults.
BITE	Built-In Test Equipment	Hardware and software providing automated fault detection and isolation.
BTB	Bus Tie Breaker	Electrical component that connects or isolates electrical buses in aircraft power distribution.
BVM	Borescope Visual Inspection	Internal inspection using a borescope camera, commonly used for engine cylinder inspections.
CAA	Civil Aviation Authority	National aviation authority (used primarily in UK and other countries; FAA equivalent).
CAME	Continuing Airworthiness Management Exposition	Document describing an operator's airworthiness management system (EASA).
CAS	Calibrated Airspeed	Indicated airspeed corrected for instrument and installation error.
CDCCL	Critical Design Configuration Control Limitations	Specific design features that must be maintained to prevent fuel tank ignition.
CDL	Configuration Deviation List	List of aircraft external parts that may be missing for a specific flight per the AFM.
CMM	Component Maintenance Manual	Manufacturer's manual for overhaul and repair of a specific component or LRU.
CMP	Configuration, Maintenance & Procedures	Document defining required configuration and maintenance for ETOPS operations.
CofA	Certificate of Airworthiness	Document issued by the NAA certifying the aircraft meets airworthiness standards.
COR	Certificate of Release	Document signed by an authorized person certifying that maintenance has been completed.
CRS	Certificate of Release to Service	UK/EASA equivalent of a return-to-service signoff.
CVR	Cockpit Voice Recorder	Records crew communications and cockpit audio; required on transport category aircraft.
CWS	Central Warning System	Aircraft system that consolidates and displays crew warnings from multiple systems.
DAIWA	Damage Inspection and Airworthiness Assessment	Process for evaluating lightning strike or impact damage.
DAS	Data Acquisition System	System that records aircraft operational data for monitoring and analysis.
DER	Designated Engineering Representative	FAA-authorized engineer who can approve major repairs or alterations.
DME	Distance Measuring Equipment	Radio navigation system providing slant-range distance to a ground station.
EASA	European Union Aviation Safety Agency	European counterpart to the FAA; regulates aviation in EU member states.
ECAM	Electronic Centralized Aircraft Monitor	Airbus system displaying aircraft system status and failure information.
ECU	Engine Control Unit	Electronic unit controlling engine fuel delivery and performance parameters.
EICAS	Engine Indicating and Crew Alerting System	Boeing/general term for engine monitoring and crew warning display.
ELT	Emergency Locator Transmitter	Automatic distress beacon activated by crash impact or manually by crew.
EMI	Electromagnetic Interference	Unwanted electromagnetic energy that can disrupt aircraft systems.
EMP	Electromagnetic Pulse	Intense burst of electromagnetic energy that can damage aircraft electronics.
ETOPS	Extended-range Twin-engine Operational Performance Standards	FAA/ICAO rules for twin-engine over-water operations.
EWIS	Electrical Wiring Interconnection System	All aircraft wiring, connectors, and associated components per FAR 25.1701.
FAA	Federal Aviation Administration	U.S. government agency responsible for civil aviation regulation and safety.
FADEC	Full Authority Digital Engine Control	Computer system providing complete electronic control of engine parameters.
FAR	Federal Aviation Regulation	U.S. aviation regulations codified in Title 14 of the Code of Federal Regulations.
FBO	Fixed Base Operator	Airport-based business providing fuel, maintenance, hangar, and other aviation services.
FDM	Flight Data Monitoring	Program analyzing flight data to identify operational safety trends.
FDR	Flight Data Recorder	"Black box" that records flight parameters; required on transport category aircraft.
FIM	Fault Isolation Manual	Maintenance manual used to diagnose system faults using structured troubleshooting.
FMEA	Failure Mode and Effects Analysis	Engineering analysis identifying potential failures and their safety impact.
FMS	Flight Management System	Onboard computer integrating navigation, performance, and guidance functions.
FOD	Foreign Object Damage/Debris	Damage to aircraft or engine caused by foreign objects; also refers to the objects themselves.
FSDO	Flight Standards District Office	FAA regional office overseeing aviation safety and certification activities.
GCU	Generator Control Unit	Regulates aircraft generator output and protects electrical system from faults.
GPS	Global Positioning System	Satellite-based navigation system providing position, velocity, and time data.
GPWS	Ground Proximity Warning System	System that warns crew of unsafe proximity to terrain.
HF	High Frequency	Radio range (3-30 MHz) used for long-range aviation communications.
HIRF	High Intensity Radiated Fields	Electromagnetic environment that can interfere with aircraft systems; design standard per FAR 25.1317.
HMDB	Hazardous Material Data Base	Database of hazardous materials and handling requirements.
HSI	Horizontal Situation Indicator	Flight instrument combining heading, course, and navigation information.
HUD	Head-Up Display	Transparent display projecting flight data into the pilot's forward field of view.
ICA	Instructions for Continued Airworthiness	Manufacturer's maintenance requirements mandated by FAR 21 for TC holders.
ICAO	International Civil Aviation Organization	UN specialized agency setting international aviation standards.
IFR	Instrument Flight Rules	FAA regulations governing flight in IMC; also refers to a flight plan filed under those rules.
IGV	Inlet Guide Vane	Variable vane at engine compressor inlet controlling airflow direction.
IMC	Instrument Meteorological Conditions	Weather conditions below VFR minimums requiring instrument flight.
INS	Inertial Navigation System	Self-contained navigation using accelerometers and gyroscopes; no external signals needed.
IPC	Illustrated Parts Catalog	Manual providing part numbers and exploded diagrams for aircraft components.
IRS	Inertial Reference System	Modern INS using laser ring gyros; provides attitude, heading, and position data.
LRU	Line Replaceable Unit	Component designed for quick removal and replacement at the line maintenance level.
MALSR	Medium Intensity Approach Lighting System with Runway Alignment Indicator Lights	Airport approach lighting system.
MEL	Minimum Equipment List	Approved list of equipment that may be inoperative for dispatch under specific conditions.
MFD	Multi-Function Display	Configurable cockpit display showing navigation, system, and weather data.
MMEL	Master Minimum Equipment List	FAA-approved master list from which operators develop their aircraft-specific MEL.
MOC	Means of Compliance	Acceptable method for meeting a regulatory or certification requirement.
MRB	Maintenance Review Board	Industry-FAA body that establishes initial scheduled maintenance requirements for new aircraft types.
MRBR	Maintenance Review Board Report	Document establishing initial maintenance program requirements for a new aircraft type.
MRO	Maintenance, Repair & Overhaul	Organization or activity performing aircraft maintenance work; also the industry term.
MSB	Mandatory Service Bulletin	Service bulletin issued by a manufacturer that must be complied with (often tied to an AD).
MSG-3	Maintenance Steering Group 3	Analytical process used to develop efficient scheduled maintenance programs.
MSN	Manufacturer Serial Number	Unique serial number assigned to an aircraft at production.
NDI	Non-Destructive Inspection	Synonym for NDT; used interchangeably in maintenance documentation.
NDT	Non-Destructive Testing	Inspection methods (dye penetrant, ultrasonic, eddy current, X-ray) that don't damage the part.
NOTAM	Notice to Airmen	Official notice containing information essential to flight operations.
OAT	Outside Air Temperature	Ambient air temperature measured outside the aircraft.
OEM	Original Equipment Manufacturer	The original manufacturer of an aircraft, engine, or component.
OHC	Overhaul Check	Scheduled heavy maintenance event restoring components to serviceable limits.
PAR	Precision Approach Radar	Ground-based radar system providing guidance to landing aircraft.
PAX	Passengers	Standard abbreviation for aircraft passengers in maintenance and ops documentation.
PFD	Primary Flight Display	Main cockpit display showing attitude, airspeed, altitude, and heading.
PMA	Parts Manufacturer Approval	FAA approval allowing a manufacturer other than the OEM to produce replacement parts.
QEC	Quick Engine Change	Kit and procedure for rapid engine replacement using pre-assembled components.
QRH	Quick Reference Handbook	Pilot reference for abnormal and emergency procedures.
R&R	Removal and Replacement	Common maintenance shorthand for removing and installing a component.
RII	Required Inspection Item	Maintenance task that must be inspected by a second, independent certificated person.
RVSM	Reduced Vertical Separation Minimum	Airspace where aircraft maintain 1,000 ft separation between FL290-FL410.
SAF	Safety Management System	Systematic approach to managing safety risk in aviation organizations.
SATCOM	Satellite Communications	Aircraft communication system using satellite links for voice and data.
SB	Service Bulletin	Manufacturer-issued maintenance instructions; may be mandatory (via AD) or optional.
SI	Service Instruction	Lycoming's term for manufacturer maintenance guidance (equivalent to SB for other manufacturers).
SL	Service Letter	Manufacturer communication providing maintenance information or recommendations; typically less urgent than SBs.
SMS	Safety Management System	Organizational framework for managing aviation safety risks and promoting safety culture.
SOC	Statement of Compliance	Document certifying that a product or procedure meets specified requirements.
SPM	Standard Practices Manual	Manual covering general maintenance practices applicable across aircraft types.
SRM	Structural Repair Manual	Manual providing approved methods for repairing aircraft structure.
SSB	Single Sideband	Radio transmission mode used in HF communications for long-range voice.
STC	Supplemental Type Certificate	FAA approval for a modification or alteration to a type-certificated product.
TAWS	Terrain Awareness and Warning System	Enhanced GPWS providing forward-looking terrain avoidance.
TBO	Time Between Overhaul	Manufacturer-recommended interval between engine or component overhauls (not always mandatory for Part 91).
TCAS	Traffic Collision Avoidance System	Onboard system providing traffic advisories and collision avoidance.
TCDS	Type Certificate Data Sheet	FAA document listing the approved configuration and limitations of a type-certificated aircraft.
TOLD	Takeoff and Landing Data	Calculated performance data for specific runway/weight/atmospheric conditions.
TSN	Time Since New	Total operating hours or cycles since a component was manufactured.
TSO	Technical Standard Order / Time Since Overhaul	FAA minimum performance standard for specified avionics and equipment. Also used for Time Since Overhaul (context-dependent).
UHF	Ultra High Frequency	Radio range (300 MHz - 3 GHz); used for military aviation and some navigation aids.
VFR	Visual Flight Rules	FAA regulations governing flight in VMC; pilots navigate by visual reference.
VHF	Very High Frequency	Radio frequency range (30-300 MHz) used for aviation voice communications.
VMC	Visual Meteorological Conditions	Weather conditions meeting VFR minimums; flight by visual reference.
VMO	Maximum Operating Speed	Maximum allowable indicated airspeed in level flight.
WDM	Wiring Diagram Manual	Manual containing complete aircraft wiring schematics and wire routing data.
WO	Work Order	Document authorizing and tracking maintenance work performed on an aircraft or component.
ZFW	Zero Fuel Weight	Maximum allowable weight of an aircraft without usable fuel; structural design limit.