What does an annual or 100-hour inspection include?
October 20, 2026 · Chris van Eijk
An annual inspection and a 100-hour inspection cover the same ground. The FAA sets one scope for both in 14 CFR part 43, Appendix D, titled "Scope and Detail of Items (as Applicable to the Particular Aircraft) To Be Included in Annual and 100-Hour Inspections". This guide walks through what that appendix lists, what 43.15 adds, and what EASA's minimum inspection programme asks for a European aeroplane. All three rules were read at the primary source on 20 October 2026.
Short answer: An annual or 100-hour inspection under FAA rules opens the aircraft up, cleans it, and inspects nine groups: fuselage and hull, cabin and cockpit, engine and nacelle, landing gear, wing and center section, empennage, propeller, radio, and any other installed item. The inspector must use a checklist that includes at least the items of Appendix D. Before return to service the engine must be run; for a piston engine the rule names four checks: power output, magnetos, fuel and oil pressure, and cylinder and oil temperature. EASA's minimum inspection programme names much the same areas of an aeroplane and the same engine checks.
What the inspection covers, FAA and EASA
FAA: 14 CFR part 43, Appendix D
(b) Fuselage and hull · 3 items
Fabric and skin — for deterioration, distortion, other evidence of failure
(c) Cabin and cockpit · 7 items
Seats and safety belts — for poor condition and apparent defects
(d) Engine and nacelle · 11 items
Internal engine — for cylinder compression and for metal particles or foreign matter on screens and sump drain plugs
(e) Landing gear · 10 items
Wheels — for cracks, defects, and condition of bearings
(f) Wing and center section · one paragraph
all components, for poor general condition, fabric or skin deterioration, distortion, evidence of failure
(g) Empennage · one paragraph
all components and systems of the complete empennage assembly
(h) Propeller · 4 items
Propeller assembly — for cracks, nicks, binds, and oil leakage
(i) Radio · 4 items
Wiring and conduits — for improper routing, insecure mounting, and obvious defects
(j) Miscellaneous · one paragraph
each installed item not otherwise covered
EASA: minimum inspection programme, aeroplane areas
- airframe
- cabin and cockpit
- landing gear
- wing and centre section
- flight controls
- empennage
- avionics and electrics
- power plant
- clutches and gearboxes
- propeller
- miscellaneous systems, such as the ballistic rescue system
Before the inspection: open and clean
Appendix D starts with paragraph (a): "Each person performing an annual or 100-hour inspection shall, before that inspection, remove or open all necessary inspection plates, access doors, fairing, and cowling. He shall thoroughly clean the aircraft and aircraft engine." Shops that publish a flat rate also list opening and closing the aircraft as part of it.
The nine groups
Paragraphs (b) to (j) list what to inspect, each "where applicable", and what to look for. A few of the 39 numbered items show the level of detail:
- Engine and nacelle, 11 items, among them "Internal engine—for cylinder compression and for metal particles or foreign matter on screens and sump drain plugs", "Engine mount—for cracks, looseness of mounting, and looseness of engine to mount" and "Exhaust stacks—for cracks, defects, and improper attachment".
- Landing gear, 10 items: from "Wheels—for cracks, defects, and condition of bearings" and "Tires—for wear and cuts" to "Brakes—for improper adjustment".
- Cabin and cockpit, 7 items, including "Seats and safety belts—for poor condition and apparent defects" and "Batteries—for improper installation and improper charge".
- Propeller, 4 items, starting with "Propeller assembly—for cracks, nicks, binds, and oil leakage".
- Radio, 4 items: equipment, "Wiring and conduits", bonding and shielding, and antennas.
- Fuselage and hull, 3 items, among them "Fabric and skin".
The wing and center section, the empennage and "each installed miscellaneous item that is not otherwise covered by this listing" each get one paragraph instead of a list.
The checklist and the engine run
Section 43.15(c) adds two duties. First: "Each person performing an annual or 100-hour inspection shall use a checklist while performing the inspection." The checklist "may be of the person's own design, one provided by the manufacturer of the equipment being inspected or one obtained from another source", but it "must include the scope and detail of the items contained in appendix D". Second, the engine must be run before the aircraft goes back into service, "to determine satisfactory performance in accordance with the manufacturer's recommendations": for a piston engine the four checks below (43.15(c)(2)), for a turbine engine to the manufacturer's recommendations alone (43.15(c)(3)).
The engine run after the inspection
| FAA 43.15(c)(2) | EASA ML.A.302(d)(2)(f)(i) |
|---|---|
| Power output (static and idle r.p.m.) | power and revolutions per minute (rpm) |
| Magnetos | magnetos |
| Fuel and oil pressure | fuel and oil pressure |
| Cylinder and oil temperature | engine temperatures |
Above all of that, 43.15(a)(1) sets the goal of every inspection under part 91: to "determine whether the aircraft, or portion(s) thereof under inspection, meets all applicable airworthiness requirements."
What EASA's minimum inspection programme asks
In Europe, a light aeroplane is maintained to an aircraft maintenance programme. If that programme follows the minimum inspection programme of Part-ML, it is inspected every year or every 100 hours, whichever comes first, with a tolerance of one month or 10 hours, and the next interval runs from the inspection (ML.A.302(d)). The tasks of that inspection are listed in ML.A.302(d)(2), "as applicable to the aircraft type":
- servicing tasks as required by the design approval holder;
- inspection of markings;
- review of weighing records, and weighing where the operating rules require it;
- an operational test of the transponder, if installed, and a functional test of the pitot-static system;
- for aeroplanes, operational tests of the power plant: power and rpm, magnetos, fuel and oil pressure and engine temperatures; the published run-up procedure for an engine with automated engine control; and, for dry-sump, turbocharged and liquid-cooled engines, a test for signs of disturbed fluid circulation;
- an inspection of the condition and attachment of the structural items, systems and components in the areas shown in the figure above, from the airframe to "miscellaneous systems, such as the ballistic rescue system".
Some items on the EASA list have no counterpart in Appendix D: the servicing tasks, the weighing records and the fluid-circulation test. Appendix D also has no dedicated transponder or pitot-static test; it only asks for instruments and radio equipment to be inspected for condition, mounting and operation. The FAA covers two of those in separate rules on their own 24-calendar-month cycle: the transponder (91.413) and, for flight under IFR in controlled airspace, the static pressure system and altimeter (91.411). EASA's list ties its tests to the annual/100-hour inspection.
Is a 50-hour inspection required?
Not by these rules. 14 CFR 91.409 sets the annual, the 100-hour, a progressive inspection and the programmes of paragraph (e) for large and turbine-powered aircraft, and no 50-hour interval. EASA's minimum inspection programme in ML.A.302(d) sets "every annual or 100-h interval" and no 50-hour interval either. Shops still price a 50-hour check: A-Maintenance in Germany lists €830 for a Cessna 172 and Flugschule Basel CHF 1,056, both excluding VAT. Whether your aircraft needs one is set by its maintenance programme or the manufacturer's instructions, which ML.A.302(d)(2) brings in as "servicing tasks as required by the DAH's requirements".
Annual or 100-hour: same checklist, different signature
Because Appendix D applies to "Annual and 100-Hour Inspections" alike, the difference lies elsewhere. It is who may sign off, how often each is due and which flights need the 100-hour. See does a flying club aircraft need a 100-hour inspection? for that, and how much does an annual inspection cost? for the flat rates 16 shops publish for doing it.
Keeping track of when it is due
The checklist is the mechanic's; when it is due is the owner's or the club's. In Pilot-Next a maintenance plan holds the interval in hours, months or both. Every settled flight moves the meter, and pilots see the next item due on the schedule while they book. Under FAA rules the transponder and static-system tests fit the same way, as plans on 24 months; Pilot-Next counts the months from the day of completion, which falls slightly before the end of the calendar month the rule allows.