The Federal Aviation Administration (FAA) issued a directive Thursday that requires airlines to do regular maintenance checks of the flight-control software on Boeing’s 737 MAX and to periodically test the operation of cutoff switches (Override) the pilots use if system failures occur.
The latest directive makes mandatory instructions released by Boeing in December that recommend planes with more than 6,000 flight hours be subject to specific electronic checks.
However, all the MAX aircrafts currently flying had these MCAS checks done before the planes returned to the sky after a 21-month grounding of the worldwide fleet.
MCAS, an automated flight control system on the B737 MAX,came to limelight after two fatal 737 MAX crashes that led to the plane's 21-month grounding that was lifted in November.
Boeing said it "fully supports the FAA mandate "requiring functional checks at certain intervals to the digital flight control system, stabilizer trim, and the primary and secondary aisle stand stabilizer."
The three repetitive inspections are to be done during existing maintenance programs, the FAA said, "to ensure the continued functioning of certain systems throughout the life of the airplane."
Boeing said it “fully supports” the directive, which affects approximately 72 MAXs registered in the U.S. and 389 of the jets worldwide.
The FAA also issued a notice on Wednesday called a Continued Airworthiness Notification to the International Community (CANIC) "to highlight the importance of these inspections to other international regulators and to operators outside the United States."
The directive impacts about 72 U.S.-registered airplanes and 389 airplanes worldwide, the FAA said.
The FAA said the directive is necessary because a "potential latent failure of a flight control system function" if combined with "unusual flight maneuvers or with another flight control system failure" could result in reduced controllability of the airplane.
The FAA said all operators of U.S.-registered 737 MAX airplanes have already included these inspections in their maintenance programs.
The 737 MAX was grounded in March 2019 worldwide after two fatal crashes in five months killed 346 people. The grounding was not lifted until November 2020 by the FAA after Boeing made significant safety upgrades and improvements in pilot training as well as adding new safeguards to MCAS.
