March 17, 2019 Flawed Safety Analysis, Failed Oversight - Why Two 737 MAX Planes Crashed Two accidents of the Boeing 737 MAX aircraft led to a loss of 338 lives. Planes of that type are now grounded world wide. We earlier explained in detail why the incidents happened. New reports confirm that take. For commercial reasons Boeing wanted the new 737 version to handle like the old ones. But changes in the new version required an additional system to handle certain flight situations. The development of that system and the safety analysis of its implications were rushed through. Pilots were not informed of it and not trained to counter its failure. Boeing now hopes that a software update, planned for April, will allow its grounded 737 MAX airplanes back to the flight line. For several reasons that is unlikely to happen. On Thursday Captain C.B. Sully Sullenberger, who successfully landed a plane on the Hudson river after a bird strike disabled both engines, spoke out against Boeing's patch up attempt: It has been obvious since the Lion Air crash that a redesign of the 737 MAX 8 has been urgently needed, yet has still not been done, and the announced proposed fixes do not go far enough. The public will not trust Boeing's, or the Federal Aviation Administration's assurances if Sullenberger sticks to his view. Another reason that Boeing's update will not suffice is a detailed bombshell report researched mostly before last Sunday's crash but just now published by the Seattle Times. It summarizes: [T]he original safety analysis that Boeing delivered to the FAA for a new flight control system on the MAX — a report used to certify the plane as safe to fly — had several crucial flaws.

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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 safety analysis: Understated the power of the new flight control system, which was designed to swivel the horizontal tail to push the nose of the plane down to avert a stall. When the planes later entered service, MCAS was capable of moving the tail more than four times farther than was stated in the initial safety analysis document .

. Failed to account for how the system could reset itself each time a pilot responded, thereby missing the potential impact of the system repeatedly pushing the airplane’s nose downward.

Assessed a failure of the system as one level below “catastrophic.” But even that “hazardous” danger level should have precluded activation of the system based on input from a single sensor — and yet that’s how it was designed. The 737 MAX maneuver characteristics augmentation system (MCAS) depends on the input of a vane on the side of the airplane.

Angle-of-attack sensor The vane measure the angle between the airflow and the wing. It thereby detects if the nose of airplane points up or down. It can easily be damaged by a ramp accident or due to a bird strike. The MCAS system depends on the input of only one of these sensors. The corrections MCAS applies to the trim of the airplane are too large for a busy pilot to counter. (A detailed explanation of the system and the accidents is provided by a professional pilot in two videos here and here.) That the system, as designed, engages repeatedly can lead to situations that are extremely difficult to handle. The Seattle Times also reports that managers at the FAA pushed their safety engineers to delegate more certification tasks to Boeing itself. Boeing was eager to get the new version of the 737 out of the door to catch up with Airbus's A-320 NEO. Shortcuts were taken to rush the safety analysis through. The MCAS system is poorly engineered and the design should never have been certified in the first place. But the issue is even worse. The certification that was given relied on false data. The first MCAS design, on which the safety analysis and certification was based, allowed for a maximum trim movement by MCAS of 0.6 degree of a maximum of 5 degree. Flight tests proved that to be too little to achieve the desired effects and the maximum movement was changed to 2.5 degree. A safety analysis for the new value was not conducted. “The FAA believed the airplane was designed to the 0.6 limit, and that’s what the foreign regulatory authorities thought, too,” said an FAA engineer. “It makes a difference in your assessment of the hazard involved.”

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“None of the engineers were aware of a higher limit,” said a second current FAA engineer. Boeing and the U.S. government have a special relation. All administrations, independent of which party rules, give it extraordinary support. That leads to regulatory capture. The FAA is under constant political pressure to relent to Boeing's demands: For Boeing’s 102-year history, dating to the start of the First World War, the company and the country have relied upon one another, together creating hundreds of thousands of jobs, outfitting the United States with top military aircraft and supplying planes worldwide to allow the growth of passenger air travel and to boost U.S. exports.

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“Whenever the government is seeking to enhance exports, usually you’re going to find that Boeing is heavily involved in whatever initiative they’re carrying out,” said Andrew Hunter, a defense industry expert with the Center for Strategic and International Studies. “That was true in the Obama administration, and it’s true in the Trump administration.”

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“The risk is obviously that when agencies that are regulatory in nature work closely with a company over a long period of time, the concern is that it could undermine its independence,” Hunter said. After the accident last Sunday Boeing used its political connections to prevent the grounding of the 737 MAX. Only after all other countries prohibited further flights did the U.S. join in. It was the president, not the FAA, who announced the decision. The new reports about the outsourcing of FAA safety analyses to Boeing itself, and of the inappropriate certification process, add to the impression that the FAA can no longer be trusted. Even if it certifies Boeing's patch-up solution for the MCAS problem other regulators will disagree. That then will become a severe political problem. Trump's trade negotiations with China depend on the Chinese willingness to buy a large number of Boeing planes. If the Chinese regulators, who were the first to ground the MAX, do not accept the solution Boeing provides, those trade negotiations will go nowhere. It is clear than that Boeing will have to provide a better solution. The U.S. government will have to strengthen its aviation regulator and will have to protect it from political pressure. Should either not happen Boeing's role in the international airline business will be severely damaged. Posted by b on March 17, 2019 at 16:26 UTC | Permalink Comments next page » next page »