How often does an aircraft need to be inspected?

How often does an aircraft need to be inspected?April 8, 2020

How often does an aircraft need to be inspected?
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A car has to be inspected regularly – but what about aircraft?

For an aircraft, the inspection intervals are determined according to the following values:

  1. Number of flights
  2. Number of flying hours.


There are generally two forms of maintenance in itself.

Many parts of an aircraft have a lifetime. Since it is precisely monitored when the part has been installed, it is always possible to trace how long the part has been in use. When the lifespan has expired, the part will be removed. It is then taken to a mechanic who checks it and gives it a general overhaul. Whenever possible, the parts are repaired so that they can be used again.  If not, the part is disposed of.


The second measure is to check very carefully those parts of the aircraft that cannot be removed or can only be removed with difficulty. These checks are not only visual inspections, a variety of technologies are used here. With a camera attached to a long thin tube (borescope), even inaccessible cavities can be viewed. Using eddy current or ultrasonic methods, even the smallest cracks in metal parts can be made visible. And if the aircraft is placed on three trestles, even the flight can be simulated and the landing gear extended and retracted.


An inspection before every flight

Before each flight the so-called “Walk-Around” or “Exterior Inspection” of the pilot is carried out. It is a visual inspection of the airplane, during which possible damage is detected. Prior to this, the aircraft has already been inspected by a mechanic who looks once a day at the most important operating materials and checks the aircraft for general damage or particular wear and tear.


The first regular check is the classic A-check. This check is performed approximately every 400-500 flight hours. For a normally used aircraft this means an intensive check every six to eight weeks. This check requires about 50 to 80 working hours. This is where the regular service checks as well as engine and function checks are carried out.


The next logical check would be the B-check. However, this is hard to find and is usually replaced by a series of A-checks.


The first really big check is the C-check: about every one and a half to two years – or about 1500 to 2000 flights – a commercial aircraft is brought to the maintenance hangar for several days. In about 2000 hours of work, a lot more time is spent looking into the depths and, above all, inspecting the structure of the airframe and load-bearing parts. If defects are found, they can be further observed at close range or repaired immediately, depending on their severity.


The check, which is symbolic of the overall safety in maintenance and thus in air traffic, is the D-check: about every six to ten years a commercial aircraft comes to the maintenance hangar for the D-check. During this general overhaul, the entire aircraft is disassembled: All installations are removed, all moving parts are removed and even the paint is removed if necessary. The aircraft can now be completely inspected and overhauled: 30 to 50,000 man-hours are needed for this, while the aircraft remains in the maintenance hangar for four to eight weeks.

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  • Ryanair