Aircraft maintenance checks

Aircraft maintenance checks are periodic inspections that have to be done on all commercial/civil aircraft after a certain amount of time or usage; military aircraft normally follow specific maintenance programmes which may or may not be similar to those of commercial/civil operators. Airlines and other commercial operators of large or turbine-powered aircraft follow a continuous inspection program approved by the Federal Aviation Administration (FAA) in the United States, or by other airworthiness authorities such as Transport Canada or the European Aviation Safety Agency (EASA). Under FAA oversight, each operator prepares a Continuous Airworthiness Maintenance Program (CAMP) under its Operations Specifications or "OpSpecs". The CAMP includes both routine and detailed inspections. Airlines and airworthiness authorities casually refer to the detailed inspections as "checks", commonly one of the following: A check, B check, C check, or D check. A and B checks are lighter checks, while C and D are considered heavier checks.

This is performed approximately every 400-600 flight hours or 200–300 cycles (takeoff and landing is considered an aircraft "cycle"), depending on aircraft type. It needs about 50-70 man-hours and is usually on the ground in a hangar for a minimum of 10 hours. The actual occurrence of this check varies by aircraft type, the cycle count, or the number of hours flown since the last check. The occurrence can be delayed by the airline if certain predetermined conditions are met.

This is performed approximately every 6-8 months. It needs about 160-180 man-hours, depending on the aircraft, and is usually completed within 1–3 days at an airport hangar. A similar occurrence schedule applies to the B check as to the A check. However, B checks may also be incorporated into successive A checks, i.e.: Checks A-1 through A-10 complete all the B check items.

This is performed approximately every 20–24 months or a specific amount of actual flight hours (FH) or as defined by the manufacturer. This maintenance check is much more extensive than a B check, requiring a large majority of the aircraft's components to be inspected. This check puts the aircraft out of service, and the aircraft must not leave the maintenance site until it is completed. It also requires more space than A and B checks. It is, therefore, usually carried out in a hangar at a maintenance base. The time needed to complete such a check is at least 1–2 weeks and the effort involved can require up to 6,000 man-hours. The schedule of occurrence has many factors and components as has been described, and thus varies by aircraft category and type.

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