Aircraft Maintenance

Maintenance means the preservation, inspection, overhaul, and repair of aircraft, including the replacement of parts. The purpose of maintenance is to ensure that the aircraft remains airworthy throughout its operational life. A properly maintained aircraft is a safe aircraft.

Although maintenance requirements vary for different types of aircraft, experience shows that most aircraft need some type of preventive maintenance every 25 hours or less of flying time, and minor maintenance at least every 100 hours. This is influenced by the kind of operation, climactic conditions, storage facilities, age, and construction of the aircraft. Maintenance manuals are available from aircraft manufacturers or commercial vendors with revisions for maintaining your aircraft.

While the requirements for maintaining your aircraft are contained in Title 14 of the Code of Federal Regulations (14 CFR), it is essential for every aircraft owner to remember that specific maintenance requirements are available from the aircraft manufacturer.


Maintenance Responsibilities

14 CFR part 91, section 91.403, places primary responsibility on the owner or operator for maintaining an aircraft in an airworthy condition. Certain inspections must be performed on your aircraft, and you must maintain the airworthiness of the aircraft between the required inspections by having any defects corrected. 14 CFR part 91, section 91.327 pertains to lightsport aircraft. Light-sport aircraft certificated in the light sport category under 14 CFR part 21, section 21.190 must be maintained by an FAA-certificated airframe and powerplant (A&P) mechanic or a light-sport repairman with a maintenance rating.

14 CFR Part 91, Subpart E

14 CFR part 91, subpart E, requires the inspection of all civil aircraft at specific intervals to determine the overall condition. The interval generally depends on the type of operations in which the aircraft is engaged. Some aircraft need to be inspected at least once every 12 calendar months, while inspection is required for others after each 100 hours of operation. In other instances, an aircraft may be inspected in accordance with an inspection system set up to provide for total inspection of the aircraft on the basis of calendar time, time in service, number of system operations, or any combination of these factors.

To determine the specific inspection requirements and rules for the performance of inspections, you should refer to 14 CFR part 91, subpart E, which prescribes the requirements for various types of operations.

Manufacturer Maintenance Manuals

All inspections must follow the manufacturer maintenance manual, including the instructions for continued airworthiness concerning inspection intervals, parts replacement, and life-limited items as applicable to your aircraft. The maintenance manuals provided by the manufacturer of your aircraft are your best available resource on issues of aircraft maintenance.

Preventive Maintenance

14 CFR lists 32 relatively uncomplicated repairs and procedures defined as preventive maintenance. Certificated pilots, excluding student and recreational pilots, may perform preventive maintenance on any aircraft owned or operated by them that are not used in air carrier service. These preventive maintenance operations are listed in 14 CFR Part 43, Appendix A, Preventive Maintenance. 14 CFR part 43 also contains other rules to be followed in the maintenance of aircraft.

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In order to provide a reasonable assurance that aircraft are functioning properly, the Federal Aviation Administration (FAA) requires a series of aircraft inspections somewhat similar to the many currency requirements for airmen. This section outlines the basic inspection requirements for aircraft.

Annual Inspection

Most general aviation aircraft require an annual inspection pursuant to 14 CFR part 91, section 91.409.

Excluded aircraft:

  • Use an approved progressive inspection plan;
  • Carry a special flight permit; or
  • Carry a provisional airworthiness certificate.

The annual inspection must be completed and approved by a mechanic with an inspection authorization (IA) once every 12 calendar months. For example, if the aircraft’s annual is endorsed on June 16, 2008, the next annual inspection is due before July 1, 2009; otherwise the aircraft may not be flown without authorization (e.g., a special flight or “ferry” permit).

A ferry permit is required to fly an aircraft that is out of annual, such as in the case of flying to another airport for the inspection. Chapter 5 discusses the issuance of special flight permits. You can contact your local Flight Standards District Office (FSDO) for instructions on applying for a special flight or ferry permit.

100-Hour Inspection

The 100-hour (14 CFR part 91, section 91.409) inspection is required for aircraft that either:

  • Carry any person (other than a crewmember) for hire, or
  • Are provided by any person giving flight instruction.

The 100-hour limit may be exceeded by 10 hours for the purposes of flying to a place where the inspection can be completed. The excess time must be included in computing the next 100 hours of time in service.

Some examples of “for hire” operations under 14 CFR part 91 that subject the aircraft to the 100-hour inspection requirement include:

  • An aerial photography flight, or
  • A flight instructor providing an aircraft, or any operation that supplies both flight instruction and an aircraft. (An aircraft provided by the (student) pilot receiving instruction is not subject to the 100-hour inspection.)

Condition Inspection

A condition inspection is required once every 12 calendar months for light-sport aircraft certificated in the light-sport category. In accordance with 14 CFR part 91, section 91.327, the condition inspection must be performed by “a certificated repairman (light-sport aircraft) with a maintenance rating, an appropriately rated mechanic, or an appropriately rated repair station in accordance with inspection procedures developed by the aircraft manufacturer or a person acceptable to the FAA.”


Other Inspection Programs

The annual and 100-hour inspection requirements do not apply to large (over 12,500 pounds) airplanes, turbojets, or turbopropeller-powered multiengine airplanes, or to airplanes for which the owner or operator complies with the progressive inspection requirements. Details of these requirements may be determined by reference to 14 CFR part 43, section 43.11; 14 CFR part 91, subpart E; and by inquiry at the local FSDO.

Progressive Inspection

To minimize maintenance downtime, the owner may opt for a progressive inspection plan. Progressive inspections benefit owners whose aircraft experience high usage such as fixed base operators (FBOs), flight schools, and corporate flight departments. Unlike an annual inspection, a progressive inspection allows for more frequent but shorter inspection phases, only if all items required for the annual and 100-hour inspections are inspected within the required time. The authority to use a progressive inspection plan is non-transferable. Once the aircraft is sold, an annual becomes due within 12 calendar months of the last complete cycle. The 100-hour inspection is due at the completion of the next 100 hours of operation. Most airframe manufacturers provide a boilerplate progressive maintenance plan.

14 CFR Part 43, Appendix D, Scope and Detail of Items (as Applicable to the Particular Aircraft) To Be Included in Annual and 100-Hour Inspections, contains a list of general items to be checked during inspections.

Altimeter System Inspection

The aircraft’s static system, altimeter, and automatic altitude-reporting (Mode C) system must have been inspected and tested in the preceding 24 calendar months before flying instrument flight rules (IFR) in controlled airspace. 14 CFR Part 43, Appendix E, Altimeter System Test and Inspection, lists the items that must be checked.

Transponder Inspection

The transponder must be inspected every 24 calendar months. 14 CFR Part 43, Appendix F, ATC Transponder Tests and Inspections, lists the items that must be checked. Additionally, the installation of or modification to a transponder must be inspected for data errors as well.

Preflight Inspection

A pilot is required to conduct a thorough preflight inspection before every flight to ensure that the aircraft is safe for flight. Pilots should review the maintenance status of the aircraft as a part of the preflight inspection.

Repairs and Alterations

All repairs and alterations of standard airworthiness certificated aircraft are classified as either major or minor. 14 CFR part 43, appendix A, describes the alterations and repairs considered major. Major repairs or alterations are approved for return to service on FAA Form 337, Major Repair and Alteration, by an appropriately rated certificated repair station, an FAA-certificated A&P mechanic holding an IA, or a representative of the Administrator. Minor repairs and minor alterations may be approved for return to service with a proper entry in the maintenance records by a certificated A&P mechanic or an appropriately certificated repair station.

Alterations to light-sport aircraft certificated in the light-sport aircraft category under 14 CFR part 21, section 21.190, must be authorized by the manufacturer or a person acceptable to the FAA in accordance with 14 CFR part 91, section 91.327.


Minimum Equipment List/Configuration Deviation List

If your aircraft has an approved Minimum Equipment List (MEL), the MEL should be used to determine if a flight may be initiated with inoperative aircraft equipment without the issuance of a special flight permit. Your Airplane Flight Manual (AFM) may also include a Configuration Deviation List (CDL) prepared by the manufacturer.

If your aircraft does not have an approved MEL, and you have inoperative equipment or instruments, then you must refer to 14 CFR part 91, section 91.213, to determine if a special flight permit is needed to operate the aircraft.

FAA Resources

You can find all of the maintenance requirements applicable to your aircraft in 14 CFR by accessing the relevant regulations on the FAA website at The best resource for answering questions about the maintenance necessary on your aircraft is your local FSDO.

Experimental Aircraft

If you make any major alterations to your experimental aircraft, you must notify your local FSDO of those alterations.

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