Robert Besser
21 Jul 2021

WASHINGTON D.C.: The Federal Aviation Administration (FAA) on July 15 instructed airlines operating the Boeing 737 to carry out inspections of malfunctioning switches that could affect altitude pressure in aircraft cabins.

The instructions necessitated those operating Boeing 737 aircraft to carry out inspections of switches and ensure their replacements. A total of 2,502 aircraft registered in the United States, as well as 9,315 aircraft worldwide, fall under this instruction.

This decision came in close heels after two pressure switches failed during checks on wing structures by an operator during September, reportedly in three different models of the 737 aircraft.

The agency stated that the malfunctioning of the switches could lead to failure to activate the cabin altitude warning system in the event of the plane surpassing 10,000 feet, during which time the oxygen levels could fall perilously.

Pressurization in aircraft cabins is aimed at simulating the pressure experienced at 8,000 feet.

Boeing officials said they support "the FAA's direction, which makes mandatory the inspection interval that we issued to the fleet in June."

Probes and examinations conducted subsequently have, in the FAA as well as Boeing, concluded that "the failure rate of both switches is much higher than initially estimated and, therefore, does pose a safety issue."

However, Boeing did not furnish information on the failure rate.

All 737 MAX aircraft fall under this directive.