February 25, 2026, 11:51 am | Read time: 3 minutes
The U.S. Federal Aviation Administration (FAA) has issued an immediate order for the Boeing 737 Max. The reason: Two aircraft experienced excessively high temperatures in the cabin and cockpit, which the crew could not control. The details.
There have been repeated issues in the past with aircraft from the Boeing 737 Max series. The new Airworthiness Directive (AD) applies to all Boeing models 737-8, 737-9, and 737-8200, all part of the Max family. According to the Federal Aviation Administration (FAA), 771 aircraft registered in the U.S. are affected. The cost for this first step is estimated at $65,535.
With the directive, the FAA requires operators to revise the current flight operations manual. This is intended to provide the crew with additional operating instructions and checklists for an exceptional case where the temperature cannot be regulated due to a switch. This is meant to temporarily resolve the unsafe condition of the aircraft.
Malfunction of the Air Conditioning System
The FAA published the directive on February 24 in response to incidents “with excessively high cabin and cockpit temperatures during flight that could not be regulated by the flight crew with existing procedures,” according to the document. A subsequent investigation revealed that the triggering of a specific circuit breaker in the standby power control unit (SPCU) caused the incidents.
“The SPCU controls the battery and standby buses automatically and manually,” the FAA document states. The circuit breaker BAT BUS SECT 2 is responsible for powering the air conditioning and cabin pressure functions. This includes the overheat protection circuits and manual cabin pressure control. If the switch is triggered, the mechanisms lead to a malfunction of the air conditioning system. Ultimately, this can mean “an uncontrollably high temperature in the cabin and cockpit,” the document states. The aviation authority warns: “If this condition is not corrected, it can lead to injuries or incapacitation of crew and passengers.” A safe flight, including a safe landing, is not guaranteed and may even be “impossible.”
Further Measures Necessary
The new operating directive provides the crew with procedures and individual steps in case the circuit breaker is triggered. According to the FAA, the Airworthiness Directive “describes the flight crew’s procedure for a controlled descent, the attempt to reset the triggered circuit breaker of battery bus section 2, and, if this attempt fails, the shutdown of the engine bleed air switches.”
However, according to the agency, this AD is only a “preliminary measure,” as the investigation revealed further weaknesses. Additional regulations may follow. According to the FAA, Boeing is already working on a “modification to address the unsafe condition described in this Airworthiness Directive.”