June 28, 2019
Joel Hruska

New 737 Max Flaw Keeps Jet Grounded as Past Boeing Problems Surface

Boeing’s 737 Max problem keeps getting worse. The plane has been grounded for months, after Lion Air Flight 610 and Ethiopian Airlines flight 302 both crashed, killing all 346 people aboard the two aircraft. In the aftermath of the Ethiopian Airlines crash, the FAA eventually mandated that the planes stay on the ground while Boeing worked out a fix. That fix has now been delayed again, due to the discovery of another flaw that can lead to the nose of the aircraft being pointed inappropriately downward. “Government pilots discovered that a microprocessor failure could push the nose of the plane toward the ground,” CNN reports, adding that “it is not known whether the microprocessor played a role in either crash.”

This appears to be distinct from the problem with the MCAS system, which is believed to have been critical to both previous crashes. In these events, the planes — which relied on data from a single, potentially faulty angle-of-attack sensor, without a backup sensor — drove the aircraft directly into the ground, despite pilot attempts to override it. The implication of the CNN report is that the microprocessor failure is separate from the AOA sensor failure, but there’s nothing to identify what subsystem the chip is in, or whether there are redundant parts that are supposed to take over the functionality in the event of a failure.

Once again, this will mean additional delays for the 737 Max’s return to the skies. Reuters reports that Boeing will not conduct a recertification flight until July 8, best-case, but that the delays could stretch on for several weeks more. There’s a bit of uncertainty on whether a hardware change might be required. CNN states: “Boeing engineers are trying to determine if the microprocessor issue can be fixed by reprogramming software or if replacing the physical microprocessors on each 737 Max aircraft may be required.”

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Apparently, the issue surfaced during deliberate efforts to activate the MCAS system in what sounds like edge case testing. In one of these edge cases, it was not possible to recover the vehicle in an acceptable period of time, presumably due to the microprocessor failure in question. The letter that Boeing officially released states that the FAA has asked it to resolve these issues via a further software change, distinct from the software change it had already planned to make. The writeups from both CNN and Reuters, however, state that Boeing has not determined whether it is p

ossible to actually fix the problem via software update or if a hardware replacement is required.

The Washington Post, meanwhile, points out that Boeing’s safety record has been anything but rosy. In 2015, FAA regulators discovered the company had falsified certifications on hundreds of cargo doors. Mechanics were leaving tools inside plane wings, near the cables that controlled the movements of those wings. Wires were improperly installed on 787s, increasing the risk of a fire. Boeing would repeatedly agree to fix these shortcomings and fail to do so, which led the government to wrap them up into a single global package, fined Boeing $12M, and got it to agree to fix the issues in 2015. Boeing specifically “agreed to make significant changes in its internal safety systems and practices for “ensuring compliance” with regulations.”

Despite continued problems with Boeing’s compliance, the FAA waived its right to invoke enforcement penalties last year that would have cost Boeing another $12M. Boeing reported a record operating profit in 2018, at $4.2B. According to WaPo, Boeing has had major problems following through with its own commitments. An FAA official told the paper that the US Air Force had temporarily ceased taking deliveries of Boeing tankers due to persistent problems with FOD (Foreign Object Debris) being left in or on the aircraft in question. Left-over tools in plane wings would definitely qualify. It took Boeing more than a year to notify the FAA about a software problem that disconnected a critical warning light connected to the MCAS system, for example.

Both Boeing and the FAA have generally signaled satisfaction with the FAA to-date, but there have been questions raised about just how close the manufacturer and its regulatory body have become. The FAA has generally outsourced plane safety inspections to Boeing and other manufacturers, allowing companies to ‘self-certify’ aircraft safety. In the wake of the Lion Air crash, it took the FAA days to decide the 737 Max wasn’t safe to fly after most other countries had already done so. There have been numerous allegations of improper behavior and the FAA has warned Boeing in at least one letter recently that its actions regarding an inspector constituted interference.

Also under discussion are the requirements 737 Max pilots will need to meet when the plane is recertified as airworthy. Boeing has pushed for computer-based training that could be completed on an iPad, while pilot unions and individuals like the “Miracle on the Hudson” pilot, Chelsey Sullenberger, have called for simulator training.

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