The Federal Aviation Administration has issued a directive to airlines to inspect cabin air pressure switches in all Boeing 737s for possible failures — which could lead to pilots not being warned about a dangerous loss of oxygen.
The FAA’s directive — which covers 2,502 US-registered jets among 9,315 worldwide — was prompted after an operator reported in September that both switches failed tests on three aircraft, according to Reuters.
Airlines were instructed Thursday to conduct repetitive tests of the switches and replace them if necessary.
The federal agency said failures could result in the cabin altitude warning system not activating if the internal altitude exceeds 10,000 feet, at which point oxygen levels could become perilously low.
Airplane cabins are pressurized to the equivalent of not more than 8,000 feet.
The FAA said the tests must be conducted within 2,000 flight hours since the last test of the cabin altitude pressure switches, before planes have flown 2,000 hours, or