F.A.A. tells airlines to inspect Boeing 737 switches that could pose a safety risk.

The Federal Aviation Administration on Thursday instructed airlines to inspect a pair of cabin air stress switches on all Boeing 737 planes, citing safety issues.

If the switches fail, oxygen ranges could fall dangerously low inside a aircraft with out warning. That could incapacitate flight crews, making them lose management of the aircraft.

“Addressing these failures requires immediate action,” the company stated in a directive.

Airlines haven’t reported any failures that led to a harmful drop in oxygen ranges throughout flight. But in September, an unnamed airplane operator stated the switches on three planes — all completely different 737 fashions — had failed a take a look at. Boeing determined late final yr that these failures weren’t a safety subject, however the firm and the F.A.A. later concluded that they represented a menace after additional investigation and evaluation.

The F.A.A.’s directive applies to all 737 fashions, together with the troubled 737 Max, which was banned globally in March 2019 after two deadly crashes. That ban started to be lifted late final yr and the Max has been used on hundreds of flights since.

The order, referred to as an airworthiness directive, makes necessary a advice that Boeing issued to its prospects final month, the corporate stated in a assertion. “Safety is our highest priority, and we fully support the F.A.A.’s direction,” Boeing stated.

The order applies to about 2,500 planes within the United States and over 9,300 extra worldwide. The switches should be inspected inside 2,000 flight hours of the final time they have been examined or inside 90 days of the efficient date of the order.