WASHINGTON/CHICAGO • Federal aviation regulators have ordered Boeing to fix a second problem with the flight-control system of its grounded 737 Max, the company has acknowledged.
This came as new details emerged that pilots of two planes could not counteract a malfunction of the system using the company's recommended procedures.
The pilots of Ethiopian Airlines Flight 302 performed all the procedures recommended by Boeing to save their 737 Max 8 aircraft, but could not pull it out of a flight-system-induced dive, a preliminary report into the crash concluded last Thursday.
In a brief summary of the much-anticipated preliminary report on the March 10 crash, Ethiopian Transport Minister Dagmawit Moges told reporters that the aircraft flight-control system contributed to the plane's difficulty in gaining altitude after it left Addis Ababa airport. It crashed six minutes later, killing all 157 on board.
She said the crew "performed all the procedures, repeatedly, provided by the manufacturer but was not able to control the aircraft".
As in the aftermath of a Boeing 737 Max 8 crash in Indonesia last October, attention in the Ethiopian Airlines crash has zeroed in on a flight-control system known as the Manoeuvring Characteristics Augmentation System, or MCAS, which pushes the nose of the aircraft down to avoid a stall.
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You don't want to be in a situation where there was one contributing factor to an accident, and then three weeks later, you find another one.
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But later last Thursday, Boeing confirmed to The Washington Post that it had found a second software problem that the Federal Aviation Administration (FAA) has ordered fixed - separate from the anti-stall system under investigation in the two crashes, and that had led to the aircraft's worldwide grounding.
That additional problem pertains to software affecting flaps and other flight stabilisation hardware and is therefore classified as critical to flight safety, said two officials who spoke on condition of anonymity to discuss the ongoing probe.
The realisation of a second software problem explains why the timeline that Boeing projected publicly two weeks ago for getting hundreds of the aircraft airborne again has slipped, the officials said.
Boeing initially said it planned to submit fixes for its stall-prevention system to the FAA for review two weeks ago. Last Monday, an FAA spokesman said the agency instead expected to receive the final package of software over the coming weeks.
"Obviously, we ended up at a situation that in hindsight was not supposed to happen," one of the officials familiar with the investigation told The Washington Post.
"Now, you don't want to be in a situation where there was one contributing factor to an accident, and then three weeks later, you find another one."
In a statement, Boeing called the additional problem "relatively minor", but did not offer details of how the second issue affects the plane's flight-control system.
"We are taking steps to thoroughly address this relatively minor issue and already have the solution in the works to do that."
Meanwhile, Boeing is cutting production of its 737 jetliner for the first time since the Sept 11, 2001, attacks as the planemaker works to limit financial damage from the global grounding.
By slashing output 19 per cent - to 42 airplanes a month by mid-April - Boeing will be able to reduce its spending on the 737 and preserve cash. Boeing chief executive Dennis Muilenburg outlined the plan last Friday as the company ramped up efforts to restore public confidence in the 737 Max.
"When the Max returns to the skies, we've promised our airline customers and their passengers and crew that it will be as safe as any airplane ever to fly," Mr Muilenburg said.
THE WASHINGTON POST, BLOOMBERG