The U.S. Federal Aviation Administration issued an order effective immediately.Order Boeing to address potential safety risks caused by a fault in the environmental control system of the 737 MAX series aircraft, which may cause the temperature of the aircraft cabin to rise to dangerous levels.According to relevant documents, there were two flight incidents this time where "the temperatures in the cabin and cockpit were too high and the crew could not control them through existing operating procedures." For this reason, the US Federal Aviation Administration issued an airworthiness directive on February 24. The directive covers all Boeing 737 MAX fleets in the United States.
The Authority requires operators of all Boeing 737 MAX series models currently in service (including MAX 8, MAX 8-200 and MAX 9) to update their aircraft flight manuals within 30 days and add crew operating procedures for dealing with this failure.
Boeing responded: "We support this airworthiness directive issued by the U.S. Federal Aviation Administration. We are currently stepping up the development of engineering solutions to fundamentally eliminate the possibility of such electrical failures."
Investigations into the aforementioned two incidents revealed that the cause of the failure was the tripping of a circuit breaker in the aircraft's backup power control unit, which provides power support for the aircraft's air conditioning system and cabin pressurization system.
A tripped circuit breaker "triggers an unintended erroneous electrical signal to ground" that instructs actuators to close the two ram air inlet deflector doors on the 737 MAX aircraft.
This deflector covers the air inlet that delivers cooling air to the aircraft's air conditioning heat exchanger. Once closed,The aircraft environmental control system will deliver overly hot air to the passenger cabin and cockpit, which may cause "the cabin temperature to be out of control and rise sharply."
The Federal Aviation Administration emphasized: "If the fault is not handled promptly, it may cause injuries to crew members and passengers, or even incapacitation."
Boeing revealed to the media that the company had confirmed that the "root cause of the failure was a grounding wire failure in the air conditioning system" and made it clear that previous generations of Boeing 737 series aircraft were not affected by this problem.
According to the requirements of this airworthiness directive,Each operator needs to revise the aircraft flight manual, add a special situation checklist, and clarify the specific procedures for crew members to deal with when the circuit breaker trips or the cabin temperature is too high.
