FAA orders manual revisions for Boeing 737 MAX over circuit breaker risk

The Federal Aviation Administration has issued a new airworthiness directive affecting all Boeing 737 MAX 8 and Boeing 737 MAX 8200 aircraft worldwide, citing a circuit breaker issue that could trigger dangerously high temperatures in the cabin and flight deck.

The directive applies to 2,119 aircraft globally, including 771 registered in the United States. Operators are required to revise their airplane flight manuals within 30 days to include specific crew procedures in the event that a particular circuit breaker trips, leading to an air conditioning system malfunction.

According to the FAA, two recent in-flight incidents were reported in which onboard temperatures rose sharply. The agency warned that such a malfunction could result in “uncontrollable, excessively high temperature,” potentially leading to injury or incapacitation of flight crew and passengers, and ultimately compromising the ability to maintain safe flight and landing.

Boeing said it supports the directive, which formalises operational guidance the manufacturer issued last month. The company identified the root cause as a ground wire fault in the air conditioning system and stated it is advancing an engineering fix to eliminate the possibility of the electrical fault recurring.

Boeing added that it expects the permanent solution to be incorporated into the Boeing 737 MAX 7 and Boeing 737 MAX 10 before certification and does not anticipate any impact on their certification timelines.

Southwest Airlines, which experienced one of the reported incidents, said it is working closely with both the FAA and Boeing. The carrier has informed its flight crews of the required procedures to address the specific electrical fault should it occur in service.