Mr. Elwell also said he was “not happy” with the 13-month lag between reports of a “software anomaly” involving a warning light that notifies pilots of a disagreement in sensors that measure which direction the plane is pointed, and Boeing’s actions to address the problem. Boeing discovered in 2017 that the warning light worked only on planes with an optional indicator that displayed the sensor readings. That indicator was sold as an add-on, and only 20 percent of 737 Max customers purchased it. Neither the Lion Air not the Ethiopian Airlines plane had it.
Still, Mr. Elwell said he did not believe that problem contributed to either crash.
Boeing is expected to soon submit a software fix that would keep the automated system from activating based on erroneous data, a factor in both crashes, according to agency investigators. An early version of the new software is being tested in simulators, F.A.A. officials said.
Mr. Elwell gave no timetable for when the plane might be cleared to fly again. He said the agency would clear the planes only on the recommendation of a multiagency technical advisory board made up of experts from the F.A.A., the Air Force, NASA and the Volpe National Transportation Systems Center who were not involved in the initial certification of the 737 Max.
F.A.A. officials convened a meeting with aviation officials from other countries this month to address their concerns about the plane, he said, an effort to bolster confidence in the “un-grounding” of the plane when it is finally approved.
Mr. Elwell was also pressed about why the F.A.A. did not ground the plane until China, much of Europe and Canada already had.
“Why did it take so long?” asked Eleanor Holmes Norton, a Democrat and the District of Columbia’s nonvoting delegate to the House.
Source : https://www.nytimes.com/2019/05/15/us/politics/boeing-faa-congress.html324