Types of aircraft maintenance

In order to maintain flight safety, the aircraft will be regularly inspected and repaired. The US Federal Aviation Administration (FAA) stipulates a set of special standards, and divides aircraft maintenance checks into the following categories according to the complexity:

A-level inspection (A Check)
This inspection is performed on average every 500-800 flight hours and usually requires 20 man-hours. The aircraft usually spends the night at the airport to complete this check. What is checked depends on the type of aircraft, the number of takeoff and landing cycles and the number of hours flown since the last check. The main maintenance items include: replenishment of consumables such as engine lubricating oil, aircraft hydraulic oil, and oxygen, as well as wing control surfaces (flaps, ailerons, speed brakes, etc.), tires, and brakes that are more easily damaged according to the number of takeoffs and landings or during flight , The engine is the center for maintenance.

B-level inspection (B Check)
Class B overhauls are performed on average every 4 to 6 months. Each test takes 150 man-hours and typically takes 1 to 3 days to complete in the hangar. A B-level overhaul sometimes turns into multiple A-level overhauls. For example, a level B inspection may include the inspection items from A-1 to A-10. In addition to the A-level overhaul, a detailed overhaul related to the engine is specially added.

C-level inspection (C Check)
Class C inspections are performed on average every 15-21 months, or after a specified number of flight hours. The exact time is determined by the aircraft manufacturer. C-level overhaul is more complicated and complete than A and B-level overhauls, and almost all parts of the aircraft must be overhauled. According to the regulations, the aircraft will be suspended during the inspection and cannot leave the inspection area until it is completed. C-level overhaul also takes up a lot of space and takes at least 1 to 2 weeks to complete, with a total workload of 6,000 man-hours. There are many steps in this detection, which will vary according to the type of aircraft. In addition to A and B-level inspections, the main inspection items include detailed inspections of pipelines, engines, and landing gears of various systems, as well as inspections of the body structure, fuel replenishment of various parts of the fuel tank, and regular replacement of equipment.

D-level inspection (D Check)
Also known as an overhaul or overhaul, the aircraft is towed into a hangar for 3-4 weeks and is the highest level of overhaul. The aircraft will undergo a D check every more than 10,000 flight hours. During the D Check, most aircraft will undergo modification, internal inspection of the body structure and anti-rust treatment, thorough overhaul of various systems, functional tests, and repainting of the body. Theoretically, the aircraft that passed the D Check will return to its original reliability.

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