Aviation Maintenance Glossary: 50+ Key Terms Every AME Student Should Know
Every industry has its own language, and aviation maintenance is no exception. From regulatory acronyms to technical manual designations, the terms you encounter as an AME student can be overwhelming at first. This glossary defines 50+ essential terms with clear explanations and real-world context — helping you decode the documents, pass your exams, and talk the talk on the hangar floor.
Sky Licence Team
AME exam preparation specialists — helping engineers earn their Transport Canada license since 2025
Whether you are preparing for Transport Canada exams, reading an AMM for the first time, or trying to understand a DER-approved repair disposition, this glossary will help you cut through the jargon. Each entry includes a concise definition and a real-world usage context so you understand not just what the term means, but how it applies in your daily work as an AME.
For exam-specific preparation resources, see our AME licensing guide, CARS exam guide, and complete AME exam study guide.
A
AC (Advisory Circular)
An informational document issued by aviation authorities (FAA, Transport Canada) that provides guidance on acceptable methods, techniques, and practices for complying with regulations. AC43.13-1B is the most important AC for AMEs — it covers standard repair methods for aircraft structures.
Context: Used as approved data when performing structural repairs under CAR 571. Not mandatory but provides "acceptable means of compliance."
AC43.13-1B
The FAA Advisory Circular titled "Acceptable Methods, Techniques, and Practices — Aircraft Inspection and Repair." The definitive reference for sheet metal repair, welding, corrosion treatment, composite repair, and non-destructive testing. Transport Canada accepts AC43.13-1B as approved data.
Context: Every AME should own a copy. Frequently referenced in the Airframe exam and in daily repair work.
AD (Airworthiness Directive)
A legally enforceable regulation issued by the aviation authority (Transport Canada, FAA, EASA) requiring mandatory action on an aircraft, engine, propeller, or component. ADs address known safety deficiencies and may require inspection, modification, replacement, or operational limitations.
Context: Compliance with ADs is mandatory under CAR 571. Tracking AD compliance is a core AME responsibility.
AMM (Aircraft Maintenance Manual)
The manufacturer-issued manual containing step-by-step maintenance, inspection, and repair procedures for a specific aircraft model. The AMM is the primary source of approved data for all scheduled and unscheduled maintenance.
Context: The AMM must be available and current whenever maintenance is performed. Working without the AMM is a regulatory violation.
AME (Aircraft Maintenance Engineer)
A licensed professional authorized by Transport Canada to certify that aircraft maintenance has been completed in accordance with regulatory standards. AMEs hold one of three licence categories: M (Airframe & Powerplant), E (Electronics), or S (Structures).
Context: Licensed under CAR 573. Must hold a valid Transport Canada medical certificate and meet ongoing professional development requirements.
APU (Auxiliary Power Unit)
A small gas turbine engine mounted in the aircraft (usually in the tail cone) that provides electrical and pneumatic power when the main engines are not running. Used for ground operations, engine starting, and air conditioning.
Context: Maintenance of APUs falls under the powerplant section. APUs have their own maintenance schedules and component lives.
ATA Chapters
The Air Transport Association (now Airlines for America) standardized numbering system for aircraft maintenance documentation. Each aircraft system is assigned a chapter number — e.g., ATA 32 for Landing Gear, ATA 72 for Turbine Engine, ATA 21 for Air Conditioning. The ATA iSpec 2200 specification governs this standard.
Context: Every AME must know ATA chapter numbers to navigate maintenance manuals efficiently. ATA chapter references appear on virtually every maintenance document.
AWL (Airworthiness Limitation)
Mandatory life limits or inspection intervals for critical components defined in the Aircraft Maintenance Plan (AMP). AWLs are set by the manufacturer and approved by the aviation authority. Exceeding an AWL renders the aircraft unairworthy.
Context: Tracked meticulously in maintenance records. AWL compliance is audited by Transport Canada during surveillance inspections.
B
Borescope Inspection
A non-destructive inspection method using a flexible or rigid optical probe (borescope) to examine internal surfaces of engines, components, and structures without disassembly. Essential for turbine engine hot-section inspections.
Context: Commonly used during scheduled engine inspections to check compressor and turbine blades for cracks, burning, and FOD damage.
C
CARs (Canadian Aviation Regulations)
The comprehensive regulatory framework governing all aviation activities in Canada, including aircraft maintenance, licensing, operations, and airworthiness. For AMEs, the most critical sections are CAR Parts I (General Provisions), II (Aircraft Identification), V (Airworthiness), and VI (Personnel Licensing).
Context: The CARS exam tests direct knowledge of these regulations. Every AME must maintain working familiarity with CARs.
CAR 571
Standard 571 — Maintenance. Defines the requirements for maintenance, repair, and modification of aeronautical products in Canada. Covers maintenance releases, technical records, continuing airworthiness, and approved maintenance organizations.
Context: Essential for understanding legal maintenance documentation requirements. Referenced in both the CARS and Standards exams.
CAR 573
Standard 573 — Aircraft Maintenance Engineer Licensing. Defines AME licence categories (M, E, S), experience requirements, examination standards, privileges, and limitations. The regulatory foundation for all AME licensing.
Context: Every AME candidate should know the applicable sections of CAR 573 by heart.
CDL (Configuration Deviation List)
A document approved by the aviation authority that lists non-essential airframe or engine components that may be missing or inoperative for a limited period. The CDL is aircraft-specific and supplements the MEL.
Context: A missing fairing or access panel may be permissible under the CDL, but only for a specified number of flight cycles. The AME must document the deviation in the journey log.
CRS (Certificate of Release to Service)
Also called a maintenance release. The formal certification signed by a licensed AME stating that maintenance has been completed satisfactorily and the aircraft is fit for return to service. Required under CAR 571 after any maintenance.
Context: The single most important document an AME signs. Making a false or inaccurate CRS entry can result in licence suspension or revocation.
D
DER (Designated Engineering Representative)
An individual authorized by the FAA (or equivalent national authority) to approve engineering data and modifications on behalf of the regulatory authority. DERs approve STCs, field approvals, and repair designs.
Context: When a structural repair exceeds the limits of the SRM or AMM, a DER must approve the engineering disposition.
DHC (De Havilland Canada)
A Canadian aircraft manufacturer known for rugged utility aircraft including the DHC-2 Beaver, DHC-3 Otter, DHC-6 Twin Otter, Dash 7, and Dash 8 (Q400). Many DHC aircraft are still in active service and maintained by Canadian AMEs.
Context: DHC aircraft have unique maintenance requirements — the Twin Otter, for example, has extensive corrosion inspection requirements.
E
EASA (European Union Aviation Safety Agency)
The European regulatory authority for civil aviation. EASA issues its own Type Certificates, Airworthiness Directives, and maintenance standards. EASA regulations are relevant to Canadian AMEs working on European-designed aircraft or at MROs with EASA approvals.
Context: EASA Part-145 is the maintenance organization standard for European-approved repair stations. Some Canadian MROs hold both Transport Canada and EASA certifications.
EFIS (Electronic Flight Instrument System)
A glass cockpit system that replaces traditional analog flight instruments with electronic displays. EFIS includes Primary Flight Display (PFD), Navigation Display (ND), and Engine Indication and Crew Alerting System (EICAS).
Context: AME Licence E engineers specialize in EFIS troubleshooting and repair. Common faults include display failures, symbol generator issues, and data bus faults.
F
FAA (Federal Aviation Administration)
The United States civil aviation authority. The FAA issues Type Certificates for most aircraft operating in Canada, Airworthiness Directives, and advisory circulars (including AC43.13-1B). Canadian AMEs must be familiar with FAA requirements for U.S.-registered aircraft.
Context: Transport Canada has bilateral agreements with the FAA that recognize each other's maintenance certifications under certain conditions (see CAR 571 and the BASA agreement).
FOD (Foreign Object Debris/Damage)
Any foreign object (tools, hardware, debris) left in or near an aircraft that can cause damage to engines, systems, or structures. FOD is a critical safety concern in all maintenance environments.
Context: FOD prevention programs are mandatory at all MROs. Tool control, FOD walks, and zoned inspections are standard procedures.
FMS (Flight Management System)
A computerized avionics system that automates navigation, flight planning, and performance optimization. The FMS integrates GPS, inertial navigation, VOR/DME, and ILS sensors to provide continuous position information and flight guidance.
Context: FMS database updates are a recurring Licence E task. Navigation databases must be current for IFR operations.
G
GSE (Ground Support Equipment)
Equipment used to service and maintain aircraft on the ground, including tow tractors, power carts, nitrogen carts, hydraulic test stands, engine stands, and maintenance platforms. GSE must be maintained and calibrated as part of the MRO quality system.
Context: Proper GSE operation and maintenance is critical — poorly maintained GSE can damage aircraft just as easily as poor maintenance can.
H
HPT (High Pressure Turbine)
The section of a gas turbine engine immediately downstream of the combustion chamber. The HPT extracts energy from the hot gas flow to drive the high-pressure compressor. HPT blades operate under extreme thermal and mechanical stress.
Context: HPT inspection intervals are governed by AWLs. Borescope inspection of HPT blades is a critical scheduled maintenance task on all turbine engines.
I
ICA (Instructions for Continued Airworthiness)
The manufacturer-prepared document that defines the maintenance program for an aircraft, engine, or component. The ICA includes inspection intervals, life limits, maintenance procedures, and lubrication schedules. Required under CAR 571.
Context: The ICA forms the basis of the Aircraft Maintenance Plan (AMP) for each aircraft.
IFSD (In-Flight Shutdown)
An engine shutdown that occurs in flight, either automatically or by crew action, due to a malfunction. IFSD rate is a key reliability metric for engines and airlines.
Context: IFSD events trigger mandatory investigation and reporting requirements under the ICA and CAR 571.
IPC (Illustrated Parts Catalog)
A manufacturer-issued document containing exploded-view diagrams and parts lists for an aircraft, engine, or component. The IPC is used to identify and order correct replacement parts with the proper part numbers.
Context: Every AME uses the IPC regularly to verify part numbers during installations. Using the wrong part number can have serious consequences.
M
MCC (Maintenance Control Centre)
The central operations hub within an airline or MRO that coordinates and controls all maintenance activities. The MCC manages scheduling, work packages, parts availability, and technical support for line and base maintenance.
Context: Large airline MROs have 24/7 MCCs that manage daily maintenance operations across the fleet.
MEL (Minimum Equipment List)
A document approved by the aviation authority that lists specific equipment that may be inoperative for a defined period while maintaining safe operations. The MEL is aircraft-specific and derived from the Master Minimum Equipment List (MMEL).
Context: When an MEL item is deferred, the AME must placard the inoperative equipment and make the appropriate journey log entry. MEL deferrals are temporary — there are limits on how long items can remain deferred.
MMEL (Master Minimum Equipment List)
The baseline document developed by the aircraft manufacturer and approved by the regulatory authority (Transport Canada or FAA) that establishes minimum operating equipment for the aircraft type. Each operator develops their specific MEL from the MMEL.
Context: The MMEL is more restrictive than the operator MEL — operators may add items but cannot remove items from the MMEL.
MRO (Maintenance, Repair, and Overhaul)
An organization certified to perform maintenance, repair, and overhaul services on aircraft, engines, and components. MROs range from small general aviation shops to large facilities like StandardAero, L3Harris, and Avmax.
Context: Canadian MROs are certified under CAR 573. Major MROs hold multiple certifications including Transport Canada, FAA, and EASA approvals.
N
NDT / NDI (Non-Destructive Testing / Inspection)
Inspection techniques that evaluate material properties and detect defects without damaging the component. Common NDT methods include dye penetrant, magnetic particle, eddy current, ultrasonic, radiographic (X-ray), and thermographic inspection.
Context: NDT is essential for crack detection in landing gear, engine components, and airframe structures. NDT certifications (Level I, II, III) are separate from the AME licence.
O
OEM (Original Equipment Manufacturer)
The company that designed and manufactured the aircraft, engine, or component. OEMs produce maintenance manuals, parts catalogs, and service bulletins. Examples include Boeing, Airbus, Pratt & Whitney, Honeywell, and Collins Aerospace.
Context: OEM-approved data takes precedence over other maintenance instructions. AMEs must follow the OEM's AMM and IPC.
P
PMA (Parts Manufacturer Approval)
An FAA (or Transport Canada equivalent) approval that allows a manufacturer to produce replacement parts for a type-certificated product. PMA parts are functionally equivalent to OEM parts and must meet the same airworthiness standards.
Context: PMA parts are commonly used as cost-effective alternatives to OEM parts. AMEs must verify that the PMA part is approved for the specific application.
R
RII (Required Inspection Item)
A maintenance task that requires an independent inspection by a second qualified inspector before the aircraft can return to service. RII items are critical to flight safety — examples include flight control rigging, engine installation, and landing gear retraction tests.
Context: RII programs are part of the approved maintenance organization's quality system. Performing an RII task without the required independent inspection is a serious regulatory violation.
RTS (Return to Service)
The formal process of releasing an aircraft back to operational service after maintenance. The RTS requires a completed Certificate of Release to Service (CRS) signed by a licensed AME certifying that all maintenance is complete and correct.
Context: No aircraft may fly after maintenance without a valid RTS. The AME who signs the RTS assumes legal responsibility for the work.
S
SB (Service Bulletin)
A manufacturer-issued document that provides recommendations for product improvement, modification, or enhanced inspection. Unlike Airworthiness Directives, SBs are generally not mandatory unless specifically required by an AD or the operator's AMP.
Context: Many operators choose to comply with SBs proactively. Some SBs become mandatory when they are incorporated into an AD.
SRM (Structural Repair Manual)
The manufacturer-issued manual that provides approved data for structural repairs on a specific aircraft model. The SRM defines damage limits, repair schemes, material specifications, and allowable loads for structural repairs.
Context: Repairs within SRM limits can be performed using the SRM as approved data. Repairs exceeding SRM limits require DER-approved engineering dispositions.
STC (Supplemental Type Certificate)
An approval issued by the aviation authority to modify an aircraft, engine, or component from its original design configuration. STCs cover modifications like avionics upgrades, interior reconfigurations, engine changes, and cargo conversions.
Context: AMEs installing STC modifications must follow the STC installation instructions exactly. The STC becomes part of the aircraft's approved type design.
T
TBO (Time Between Overhauls)
The manufacturer-recommended interval (in flight hours, cycles, or calendar time) between major overhauls of an engine, component, or accessory. TBO intervals are established based on reliability data and may be extended under engine health monitoring programs.
Context: Exceeding TBO renders the component unairworthy unless an approved TBO extension program is in place. TBO compliance is tracked in the AMP.
TC / TCCA (Transport Canada Civil Aviation)
The Canadian civil aviation authority responsible for regulating all aspects of aviation safety in Canada, including aircraft maintenance, licensing, and airworthiness. TCCA issues Type Certificates, AME licences, and Airworthiness Directives.
Context: All AME candidates in Canada must pass Transport Canada written exams and undergo a TCCA-administered oral and practical exam to earn their licence.
TSO (Technical Standard Order)
A minimum performance standard issued by the FAA (and adopted by Transport Canada) for specific aircraft components and materials. Components manufactured to a TSO (e.g., TSO-C112 for Mode S transponders) are accepted as meeting regulatory requirements.
Context: TSO-marked components are interchangeable and do not require individual airworthiness approval for each installation.
W
W&B (Weight and Balance)
The calculation of aircraft weight and center of gravity position to ensure the aircraft remains within certified limits. Weight and balance data must be updated after any modification, repair, or equipment change that affects aircraft weight.
Context: AMEs performing modifications must update W&B data. The W&B report is part of the aircraft technical records and must be current.
Keep Learning with Sky Licence
This glossary is just the beginning. Sky Licence offers AI-powered exam preparation for all three AME licence categories — M, E, and S — with complete TP14038E syllabus coverage. Our adaptive learning platform helps you master aviation terminology, regulations, and technical concepts through targeted practice questions and instant feedback.
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