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Turn off aircraft cabin air conditioning system during ground deicing

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On January 10, 2015, when flight MU2036 (model Boeing 737-800) was launched at Kunming Changshui Airport after the ground was de-iced and ready to take off, passengers on board opened the emergency exits above the three wings, causing the flight to abandon takeoff. According to relevant news, it was snowing heavily at Kunming Airport at that time, and most flights were delayed. In order to ensure the safe take-off of the aircraft, the aircraft was pushed to the de-icing position for ground de-icing before take-off, and the air-conditioning system of the aircraft cockpit was turned off for about 30 minutes at the same time. During the process, some passengers reported physical discomfort, which caused conflicts between the passengers and the crew. In the end, the emotional passengers opened three of the four emergency exits above the wings, causing the plane to abandon takeoff.

Why does the aircraft cabin air conditioning system need to be turned off during ground deicing?

During the ground deicing process of the aircraft, it is necessary to turn off the air conditioning system of the aircraft cabin briefly. This is because during the ground deicing process, if the aircraft air conditioning system is not turned off, the deicing liquid vapor enters the aircraft air conditioning system through the bleed air of the aircraft power unit, thereby polluting the air conditioning system. Airplane cockpit air. Therefore, before ground deicing, the aircraft engine bleed air valve, as well as the APU bleed air valve, must be closed, and the air conditioning system must be closed.pca hose price -Julong

After the ground is de-iced, it is still necessary to run the engine and APU for more than 1 minute to ensure that the contamination of the de-icing fluid is removed before opening the power unit bleed valve to restore the cabin air-conditioning system.

Aircraft ground deicing methods and procedures

Since there have been many aviation accidents caused by aircraft icing in the history of civil aviation, aircraft de-icing has become an important issue of common concern for airports and airlines.

1. Aircraft ground deicing method

In the period when the aircraft has just started to de-icing, hot water is often sprayed on the leading edge of the aircraft's wings and tail to de-icing, and the effect is very good. However, when the outside temperature is far below zero, the hot water will quickly re-freeze on the surface of the aircraft in a low-temperature environment. Only after taking off within three minutes after deicing with hot water, it can de-icing and anti-icing. , has great limitations.

The most widely used deicing method is to use a heated (greater than 80°C) mixed proportion of glycol deicing fluid to spray onto the typical surface of the aircraft to remove the ice layer and at the same time play the role of anti-icing, in one operation. Complete de-icing and anti-icing work.

2. Aircraft ground deicing procedures

For the anti-icing on the ground or in the air, each type of aircraft has a set of scientific and rigorous anti-icing procedures, which are clearly given in the Aircraft Flight Manual (AFM).

Depending on different operational requirements and local airport policies, de-icing with the engine at idle or off can be performed in the gate area, in a dedicated de-icing area, or slightly pushed away from the gate area. When de-icing is performed by de-icing personnel, the following general communication procedures apply to these different de-icing methods:

Engine off or idle (sign signal to cockpit to shut down engine)

De-icer No. 1: (before de-icing begins) "Make sure the brakes are in place. Make sure the plane is ready to spray."

Captain: (After the brakes are in place, the air conditioning components are turned off, etc.) "The brakes are in place, the air conditioning system is turned off, and the aircraft is ready for spraying."

Or before starting the use of de-icing/anti-icing fluid, the ground de-icing/anti-icing personnel shall confirm to the captain whether the aircraft is in the appropriate de-icing/anti-icing configuration, for example: "Captain, is this aircraft de-icing/anti-icing possible? anti-icing";

After completion of de-icing/anti-icing, the ground de-icing/anti-icing personnel inform the captain of the type of de-icing/anti-icing fluid used, the concentration ratio and the start time of the final use of the fluid.

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