What are Aircraft Maintenance Checks?
Aircraft maintenance checks refer to the periodic inspections every commercial and civil aircraft must go through after completing a specific number of flying hours or length of time of use. Military aircraft may or may or may not have the same maintenance checks as commercial aircraft, but it certainly has its own maintenance programs.
The aviation and airline is a highly regulated industry. Commercial operators are required to comply to continuous inspection programs established by aviation authorities of different countries. In the United States, aircraft maintenance programs are regulated by the Federal Aviation Administration (FAA), Transport Canada in Canada, and European Aviation Safety Agency (EASA) in Europe. Each operator is required to establish a Continuous Airworthiness Maintenance Program (CAMP) in its operations specifications. This should contain routine and detailed inspections of their air assets.
Commercial aircraft operators, airworthiness authorities, and MRO aerospace providers call detailed inspections as “checks.” These are the A check and B check for minor inspections, and C check and D check for major or heavier inspections. Aircraft operators are allowed to conduct lighter checks on their own facilities, but heavier checks are expected to happen at the site of a certified maintenance, repair and overhaul (MRO) company.
Here are the types of checks and their meanings:
A Check
This type of check is performed every 400–600 flight hours or 200–300 cycles (takeoff and landing = 1 aircraft cycle). This inspection, which takes approximately 50–70 man-hours, usually requires an aircraft to remain on the ground for at least 10 hours, depending on its condition, and until certain predetermined conditions are met.
B Check
This check is conducted every six to eight months, and it requires approximately 160–180 man-hours, depending on the type of aircraft and its actual condition. The check, which is conducted at an airport hangar, usually takes one to three days to complete.
C Check
Performed every 20–24 months or a specific number of manufacturer-defined flight hours, the C Check is more extensive than the A and B checks. It also involves inspection of a large number of components. Being a major maintenance routine, the C check requires an aircraft to stay in the maintenance site for at least two weeks and up to 6,000 man-hours of maintenance jobs.
3C Check
The 3C check is also known as Intermediate Layover (IL). It typically refers to light maintenance checks for corrosion or deterioration of specific parts of the airframe. Aircraft operators may also take the 3C check as an opportunity to perform cabin upgrades (such as the installation of new entertainment systems, carpeting, etc.) as these would put the aircraft on the ground and out of service for some time.
Some aircraft operators who want to perform maintenance checks and upgrades spread the job across several C checks or incorporate the 3C into D checks.
D check
The D check is the most comprehensive check designed for aircraft. Also called “heavy maintenance visit,” the D check is conducted every 6–10 years. The extent of this check can go as far as taking an entire airplane apart for inspection and repair. It is even possible for an airplane to be scraped to bare metal just to make sure that nothing is corroded or worn out.
The D check requires an aircraft to be stationed at a spacious maintenance base. The repair jobs generally take up to two months, approximately 50,000 man-hours, and about one million dollars to complete, depending on the age of the aircraft. For this reason, most aircraft operators retire their airplane when they realize that its cost of repair is greater than the actual value of the airplane. This usually happens after an airplane goes through two or three D checks.