As Boeing hustled in 2015 to catch up to Airbus and certify its new 737 MAX, Federal Aviation Administration managers pushed the agency’s safety engineers to delegate safety assessments to Boeing itself, and to speedily approve the resulting analysis. The original safety analysis that Boeing delivered to the FAA for a new flight control system on the MAX had several flaws.
That flight control system, called MCAS (Maneuvering Characteristics Augmentation System), is now under scrutiny after two crashes of the jet in less than five months resulted in Wednesday’s FAA order to ground the plane.
Current and former engineers directly involved with the evaluations or familiar with the document shared details of Boeing’s “System Safety Analysis” of MCAS, which The Seattle Times confirmed.
The people who spoke to The Seattle Times and shared details of the safety analysis all spoke on condition of anonymity to protect their jobs at the FAA and other aviation organizations.
Both Boeing and the FAA were informed of the specifics of this story and were asked for responses 11 days ago, before the second crash of a 737 MAX last Sunday. Late Friday, the FAA said it followed its standard certification process on the MAX. Citing a busy week, a spokesman said the agency was “unable to delve into any detailed inquiries.”
Boeing responded Saturday with a statement that “the FAA considered the final configuration and operating parameters of MCAS during MAX certification, and concluded that it met all certification and regulatory requirements.”
Several technical experts inside the FAA said October’s Lion Air crash, where the MCAS has been implicated by investigators in Indonesia, is only the latest indicator that the agency’s delegation of certification has gone too far.
They said that it’s inappropriate for Boeing employees to have so much authority over safety analyses of Boeing jets.
Going against a long Boeing tradition of giving the pilot complete control of the aircraft, the MAX’s system was designed to act in the background, without pilot input.
It was needed because the MAX’s much larger engines had to be placed farther forward on the wing, changing the airframe’s aerodynamic lift.
Designed to activate automatically only in the extreme flight situation of a high-speed stall, this extra kick downward of the nose would make the plane feel the same to a pilot as older-model 737s.
Boeing engineers authorized to work on behalf of the FAA developed the System Safety Analysis for MCAS, a document which in turn was shared with foreign air-safety regulators in Europe, Canada and elsewhere in the world.
The document, “developed to ensure the safe operation of the 737 MAX,” concluded that the system complied with all applicable FAA regulations.
Yet black box data retrieved after the Lion Air crash indicates that a single faulty sensor triggered MCAS multiple times during the deadly flight, initiating a tug of war as the system repeatedly pushed the nose of the plane down and the pilots wrestled with the controls to pull it back up, before the final crash.
Investigators are working to determine if MCAS could be the cause of both crashes.
The FAA, citing lack of funding and resources, has over the years delegated increasing authority to Boeing to take on more of the work of certifying the safety of its own airplanes.
Several FAA technical experts said that, as certification proceeded, managers prodded them to speed the process. Development of the MAX was lagging nine months behind the rival Airbus A320neo.
A former FAA safety engineer who was directly involved in certifying the MAX said that halfway through the certification process, “we were asked by management to re-evaluate what would be delegated. Management thought we had retained too much at the FAA.”
Even the work that was retained, such as reviewing technical documents provided by Boeing, was sometimes curtailed. When time was too short for FAA technical staff to complete a review, sometimes managers either signed off on the documents themselves or delegated their review back to Boeing.
In this atmosphere, the System Safety Analysis on MCAS, just one piece of the mountain of documents needed for certification, was delegated to Boeing.
The original Boeing document provided to the FAA included a description specifying a limit to how much the system could move the horizontal tail — a limit of 0.6 degrees, out of a physical maximum of just less than 5 degrees of nose-down movement. That limit was later increased after flight tests; it’s not uncommon to tweak the control software to refine the jet’s performance.
After the Lion Air Flight 610 crash, that number was new to FAA engineers who had seen 0.6 degrees in the safety assessment.
The bottom line of Boeing’s System Safety Analysis with regard to MCAS was that, in normal flight, an activation of MCAS to the maximum assumed authority of 0.6 degrees was classified as only a “major failure,” meaning that it could cause physical distress, but not death.
In the case of an extreme maneuver, specifically when the plane is in a banked descending spiral, an activation of MCAS was classified as a “hazardous failure,” meaning that it could cause serious or fatal injuries to a small number of passengers. That’s still one level below a “catastrophic failure,” which represents the loss of the plane with multiple fatalities.