1. Mandatory aircraft maintenance checks

The manufacturers (Boeing and Airbus, and others) impose on the companies regular mandatory technical visits, called A, B, C and D, corresponding to a given number of flight hours or an estimated life of a given aircraft. These aircraft maintenance visits are carried out according to a schedule determined by the manufacturers.

The A check occurs approximately every month or every 500 flight hours. It is usually carried out in one night at an airport facility.

The B check occurs approximately every 3 months. The inspection is usually performed overnight at an airport facility1. All systems, such as emergency equipment and navigation units, are examined.

The C check is performed approximately every 12-18 months or according to a specific number of actual flight hours defined by the manufacturer. This visit lasts one week. As the aircraft is taken out of service, a lot of space is needed, most often a maintenance hangar. The entire structure of the aircraft is examined with a fine-tooth comb.

The D check is also known as the "overhaul check" or "heavy maintenance check ". It is performed approximately every 4-5 years. It requires more time and space than the other types and must be performed in a maintenance hangar. It lasts at least 2 weeks, sometimes up to 2 or 3 months depending on the type of aircraft, its age and the number of flight hours. The companies generally take advantage of this time to install the latest improvements made by the manufacturers. The aircraft is then grounded for a long period, during which all its components are inspected and repaired if necessary.