The structure of the aircraft is precise, and the aircraft air-conditioning system is an important system module that supports the safe and stable flight of the aircraft, and plays a role in tracking and adjusting the environmental parameters of the aircraft cabin and equipment cabin.

Pre-conditioned air unit​ is a brand-new type of air-conditioning unit that is placed outside of civil aviation aircraft and uses long air supply ducts and aircraft-specific connectors to supply air to the cabin through the external air-conditioning interface at the lower part of the aircraft fuselage and the complex air supply ducts inside the fuselage wind special air conditioner.