Plane Sense Chapter 5. Aircraft Maintenance

Maintenance means the preservation, inspection, overhaul, and repair of aircraft, including the replacement of parts. A PROPERLY MAINTAINED AIRCRAFT IS A SAFE AIRCRAFT.

The purpose of maintenance is to ensure that the aircraft remains airworthy throughout its operational life.

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, climatic 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.


14 CFR section 91.403 places primary responsibility on the owner or operator for maintaining an aircraft in an airworthy condition. Certain inspections shall be performed on your aircraft, and you must maintain the airworthiness of the aircraft between required inspections by having any defects corrected.

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.

All inspections shall 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.

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

Annual Inspection.
Any reciprocating-engine powered or single-engine turbojet/turbo propeller powered small aircraft (12,500 pounds and under) flown for business or pleasure is required to be inspected at least annually by an FAA certificated A&P mechanic holding an Inspection Authorization (IA), by an FAA certificated repair station that is appropriately rated, or by the manufacturer of the aircraft. The aircraft may not be operated unless the annual inspection has been performed within the preceding 12 calendar months. A period of 12 calendar months extends from any day of a month to the last day of the same month the following year. However, an aircraft with the annual inspection overdue may be operated under a special flight permit issued by the FAA for the purpose of flying the aircraft to a location where the annual inspection can be performed.

100-Hour Inspection.
Reciprocating-engine powered and single-engine turbojet/turbo propeller powered aircraft (12,500 pounds and under) used to carry passengers for hire or used for flight instruction shall be inspected within each 100 hours of time in service by an FAA certificated A&P mechanic, an FAA certificated repair station that is appropriately rated, or the aircraft manufacturer. An annual inspection is acceptable as a 100-hour inspection, but the reverse is not true.

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 section 43.11; 14 CFR part 91, subpart E; and by inquiry at the local FSDO.

Altimeter System Inspection.
14 CFR section 91.411 requires that the altimeter, encoding altimeter, and related system be tested and inspected in the preceding 24 calendar months before being operated in controlled airspace under Instrument Flight Rules (IFR).

Transponder Inspection.
14 CFR section 91.413 requires that before a transponder can be used under 14 CFR section 91.215(a), it shall be tested and inspected within the preceding 24 calendar months.

Preflight Inspection.
The CFR’s require a pilot to conduct a thorough preflight inspection before every flight to ensure that the aircraft is safe for flight.


The CFR’s list approximately two dozen 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, under Preventive Maintenance. 14 CFR part 43 also contains other rules to be followed in the maintenance of aircraft.


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

Modifications of experimental aircraft require the notification of your local FSDO.