The periodic inspection cycle of European and American aircraft: Usually classified as A, B, C, D according to flight time or landing gear.
Generally speaking, 4A = B 4B = C 8C = D250FH is an A inspection, 4000FH is a C inspection (16A), 24000FH is a D inspection (6C) The flight intervals of various inspections mainly depend on the aircraft type.
The aircraft was parked during scheduled inspections, and some parts were inspected or replaced as needed.
D inspection, also known as overhaul and renovation;
This is a comprehensive overhaul of the aircraft after a long period of operation and must be carried out in the workshop of the maintenance base, where the aircraft was parked for more than 10 days.
D inspection is the highest level of inspection and maintenance, as well as the comprehensive inspection and decoration of various aircraft systems.
Since the interval between D inspections is usually more than 10,000 flight hours, many aircraft will undergo structural or large parts modification or replacement during D inspections.
In theory, the D-tested aircraft will be fully restored to the original reliability of the aircraft, and the number of flights of the aircraft will be counted starting from “0”.
A Inspection does not require a special flight day for parking maintenance.
Post-flight inspection time after the completion of routine flight tasks is used to perform this work.
The flight interval of A inspection of the same model may not be fixed. The aircraft operator and the maintenance department of the airline shall make corresponding adjustments according to the actual operation state of the aircraft and accumulated maintenance experience, and shall expand it to appropriately reduce unnecessary maintenance costs.
In practice, aircraft operators and airline maintenance departments often cancel B inspection and adjust B inspection items to A or C inspection to reduce unnecessary parking maintenance time.
For the home Boeing 737, the A test is usually set to 200 hours, there is no B test, and the C test is 3200 hours.
Special maintenance: Maintenance performed for special reasons. Some theories also classify this type of maintenance as line maintenance or routine maintenance.
Such maintenance usually includes: special inspection and maintenance of certain parts of equipment and aircraft structure after lightning strike, heavy landing or bumpy flight;
Repair after foreign body impact or abrasion;
Rust removal and anti-corrosion treatment were carried out after corrosion was found in some parts of the aircraft. The aircraft was added or modified according to the requirements of the airworthiness department or the manufacturer. Intermediate inspection (IL inspection) was added in the two D inspections, or the cabin was renovated.
