Officials have issued a new alert for Boeing 737 Max planes this week.
The FAA published an airworthiness directive (AD) for the aircraft on June 29 due to the risk of the cabin overheating.
According to the AD, the problem can occur when a tripped circuit breaker causes ram air doors to close, which prevents the air conditioning system from cooling hot air from the engine, called bleed air.
The alert applies to all 737 Max 8 and 9 planes in service and directs airlines to revise their existing airplane flight manuals with new operating procedures if the circuit is tripped.
The problem was “prompted by reports of in-flight events of excessive cabin and flight deck temperatures that could not be controlled by the flightcrew using existing procedures,” according to the documents.
The FAA first addressed the issue with an AD in February 2026. “This air conditioning system malfunction could cause an uncontrollable, excessively high temperature in the cabin and flight deck,” says the bulletin from February.
The latest AD provides new procedures for flightcrew, including resetting the tripped circuits and possibly turning engine bleed switches off. The alert says that “the risk to the flying public justifies forgoing notice and comment prior to adoption of this rule.”
If not addressed, the overheated cabin “could lead to injury or incapacitation of flightcrew and passengers, which could result in the inability to maintain safe flight and landing,” the AD says.
The rule will take effect in the federal register in mid-July.
The FAA said that the procedures in its most recent directive are just an interim fix, and that Boeing is working on modifying the system to address the issue permanently.
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