Checks for Aircraft

A Check

This is performed approximately every month or 500 Flight Hours (FH). This check is usually done overnight at an airport gate. The actual occurrence of this check varies by aircraft type, the cycle count (takeoff and landing is considered an aircraft "cycle"), or the number of hours flown since the last check. The occurrence can be delayed by the airline if certain predetermined conditions are met.

[edit]B Check

This is performed approximately every 3 months. This check is also usually done overnight at an airport gate. A similar occurrence schedule applies to the B check as to the A check. B checks may be incorporated into successive A checks, ie: A-1 through A-10 complete all the B check items.

[edit]C Check

This is performed approximately every 12–18 months or a specific amount of actual Flight Hours(FH) as defined by the manufacturer. This maintenance check puts the aircraft out of service and requires plenty of space - usually at a hangar at a maintenance base. The schedule of occurrence has many factors and components as has been described, and thus varies by aircraft category and type.

[edit]D Check

This is the heaviest check for the airplane, also known as a Heavy Maintenance visit (HMV). This check occurs approximately every 4–5 years. This is the check that, more or less, takes the entire airplane apart for inspection. This requires even more space and time than all other checks, and must be performed at a maintenance base. Often, older aircraft being phased out of a particular airlines' fleet are stored or scrapped upon reaching their next check.

Modern transport category airplanes with MSG-3 derived maintenance programs employ usage parameters for each maintenance requirement such as flight hours, calendar time, or flight cycles. Maintenance intervals based on usage parameters allow more flexibility in scheduling the maintenance program to optimize aircraft utilization and minimize aircraft downtime.

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