Old 7th Jun 2019, 17:26
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Join Date: Feb 2006
Location: USA
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Seattle Times article

Boeing didn’t plan to fix 737 MAX warning light until 2020
June 7, 2019 at 9:17 am Updated June 7, 2019 at 9:52 am

By Mike Baker
Seattle Times staff reporter

After discovering a problem in 2017 with a cockpit warning light on the 737 MAX, Boeing decided it would defer an update to fix the issue until 2020, congressional officials said Friday.

Even as it continued delivering MAX airplanes to customers, Boeing had kept quiet the details of the problem, which prevented a light from warning pilots when there was disagreement between the plane’s angle-of-attack sensors. Those sensors are now suspected of playing in a role in two MAX crashes.

The company didn’t disclose the issue to the FAA until after a 737 MAX crash in Indonesia last year, something that frustrated FAA leadership. Now, leaders with a transportation committee in the U.S. House said they have obtained information about the initial plan to fix the issue in 2020, although they did not immediately explain the origin of that information. They have sent letters to Boeing, the FAA and supplier United Technologies requesting documents around the problematic alert.

“An important part of the Committee’s investigation is finding out what Boeing knew, when the company knew it and who it informed,” said Rep. Rick Larsen, a Washington state Democrat who leads the aviation subcommittee. “I have questions about the decision to not deem the AOA Disagree alert as safety critical and I am concerned it took Boeing so long to report this defective feature to the FAA and its customers.”

Boeing has said its engineers discovered that the warning light wasn’t functioning in 2017. The company determined that the issue did not adversely impact the safety or operation of the plane.

The warning light, which is standard on the MAX and included in the pilot manuals, is designed to light up if there’s a disagreement between the two sensors on either side of the plane’s nose that measure the jet’s angle of attack — the angle between the oncoming air flow and the airplane’s wing.

At the time of the crashes, the alert worked only on planes flown by airlines that had bought a different indicator added to the main flight-display panel. Lion Air and Ethiopian Airlines did not have those packages.

If it had been working, the warning light would have lit up on the fatal flights of both the Lion Air and Ethiopian jets. It’s not clear that it would have made a difference, as Lion Air pilots were unaware of the MAX’s new automated maneuvering system that pushed the plane’s nose down in response to the erroneous angle-of-attack data.

With knowledge of the overall system in the wake of the Lion Air crash, the Ethiopian pilots might have benefited from the information, but a preliminary report suggests they were ultimately able to diagnose the problem. They still weren’t able to maintain control of the plane.

Mike Baker: 206-464-2729 or [email protected]; on Twitter: @ByMikeBaker.
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