Aircraft cabin odor is a very common fault. Once it occurs, it is usually difficult to confirm and eliminate the fault. This is because the aircraft air conditioning system is associated with many other systems (such as engine air supply, APU air supply, etc.).

The full name of APU is Auxiliary Power Unit. Its core part is a turbine engine, which is generally installed in the tail cone part of the rear end of the aircraft.

During the ground deicing process of the aircraft, it is necessary to turn off the air conditioning system of the aircraft cabin briefly.