B737-8 Max - Det ser ikke bra ut for Boeing - Curt Lewis

Ethiopian Airlines pilots followed Boeing's emergency procedures before crash: report Boeing 737 Max simulator flight (CNN)Pilots flying Ethiopian Airlines Flight 302 initially followed emergency procedures that were laid out by Boeing before the plane nose-dived into the ground, according to preliminary findings reported in the Wall Street Journal. Citing unnamed sources familiar with the investigation, the WSJ reported that despite following the steps, which included turning off an automated flight-control system, pilots could not regain control of the Boeing 737 MAX 8. CNN has not been able to confirm details of the report. Earlier this month, the Federal Aviation Administration agency grounded all Boeing 737 Max planes, saying it had identified similarities between the Ethiopian Airlines crash and the Lion Air crash in Indonesia six months earlier. Ethiopian Airlines Flight 302 crashed the morning of March 10 after taking off from Addis Ababa on its way to Nairobi, Kenya, killing all 157 people on board. Lion Air Flight 610 crashed into the Java Sea in Indonesia on October 29 after taking off from Jakarta. All 189 people on board died. Following the Lion Air crash, Boeing issued an "Operations Manual Bulletin" advising airline operators how to address incorrect cockpit readings. It pointed airlines "to existing flight crew procedures to address circumstances where there is erroneous input from an AOA (angle of attack) sensor," a Boeing statement said. If confirmed, the findings reported in the Wall Street Journal suggest that following emergency procedures in the Boeing handbook may not have been sufficient enough to prevent a crash. The reported findings come from a preliminary report that's required by the investigating authority to be produced within 30 days of an incident. The findings are not final and subject to change as the investigation continues. Other reported preliminary findings from data retrieved from the Ethiopian Airlines jet's black box suggest that the flight-control feature, called the Maneuvering Characteristics Augmentation System (MCAS), automatically activated before the crash. The MCAS is a system that automatically lowers the nose of the plane when it receives information from its external angle of attack (AOA) sensors that the aircraft is flying too slowly or steeply, and at risk of stalling. In the Lion Air crash, the MCAS forced the plane's nose down more than 24 times before it finally hit water, according to a preliminary investigation by Indonesia's National Transportation Safety Committee, which also found the system was responding to a faulty sensor. US pilots who fly the Boeing 737 Max have also registered complaints about the way the jet has performed in flight, according to a federal database accessed by CNN. Investigators have pointed to whether pilots had sufficient training with the system. According to Ethiopian Airlines CEO Tewolde GebreMariam, pilots transitioning to the Boeing 737 Max 8 aircraft from older 737 models were required only to undertake a short computer-based training program prescribed by Boeing and approved by the FAA. GebreMariam also said the flight simulator that pilots trained on to learn how to fly the Boeing 737 Max 8 plane did not replicate the MCAS automated feature that crash investigators are scrutinizing. Pilots' union spokesmen for Southwest and American said the self-administered course -- which one pilot told CNN he took on his iPad -- highlighted the differences between the Max 8 and older 737s, but did not explain the MCAS feature. Boeing has said it is working on a software fix for the 737 MAX jets but the FAA said on Monday that the company concluded "additional work" is needed. "The FAA expects to receive Boeing's final package of its software enhancement over the coming weeks for FAA approval," the agency said in a statement. "Time is needed for additional work by Boeing as the result of an ongoing review of the 737 Max Flight Control System to ensure that Boeing has identified and appropriately addressed all pertinent issues." On Tuesday, a new Senate investigation was launched after whistleblower reports raised questions about whether FAA inspectors who reviewed the Boeing 737 MAX for certification were properly trained. https://www.cnn.com/2019/04/03/africa/ethiopian-airlines-emergency-procedures-intl/index.html Back to Top

MIT Expert Highlights 'Divergent Condition' Caused By 737 MAX Engine Placement In this photo taken with a fish-eye lens, a Boeing 737 MAX 8 airplane sits on the assembly line during a brief media tour in Boeing's 737 assembly facility, Wednesday, March 27, 2019, in Renton, Wash. AP Photo/Ted S. Warren Boeing is making airlines nervous -- they're wondering whether it's rushing too fast to get regulatory agencies around the world to approve what it says is the fix to the problems with its 737 MAX -- two of which have crashed since last October -- claiming 346 lives. There are big bucks hanging on how well Boeing handles this challenge. Boeing has $50 billion worth of orders for the 737 MAX, according to the Wall Street Journal. But the global fleet was grounded last month with the FAA being the last of global airline regulators to conclude that the plane should not fly until the suspected cause of those crashes is identified and fixed. But an MIT expert I interviewed sounds confident that Boeing will do the right thing. (I have no financial interest in the securities mentioned in this post). As I wrote last month, the Journal reported that Boeing engineers found that under certain conditions the 737 MAX's engine -- which were larger and located higher and closer to the front -- boosted the chances that the aircraft would tilt upward too steeply -- causing the plane to stall. To offset that risk, Boeing engineers installed a Maneuvering Characteristics Augmentation System (MCAS) in the 737 MAX "to compensate for the extra pitch up produced by its larger engines at elevated angle-of-attack (AOA)," noted the Journal. If the AOA sensor detected too steep a pitch, the MCAS would elevate the horizontal stabilizer -- the little wings on the airplane's tail -- to push down the nose of the plane. The 737 MAX has two AOAs in its nose that measure air pressure to calculate its pitch. According to Newsy, in the original MCAS design, a signal from just one of the AOA sensors could trigger the MCAS to push down the nose repeatedly. If that AOA was faulty, the MCAS would push the nose down even though the 737 MAX was not actually stalling -- thus sending it into a nosedive. While there is no final conclusion about the cause, a preliminary probe found that this is why Lion Air 610 crashed last October killing all 189 people onboard. According to the Journal In the Lion Air crash, the stall-prevention system, based on erroneous sensor information, repeatedly pushed the plane's nose down. According to a preliminary accident probe, the pilot battled the flight controls while facing a cacophony of alarms before losing control and plunging into the Java Sea. An MIT expert raised a question in my mind of whether Boeing's fundamental design mistake was with the size and placement of the 737 MAX engine. That's because the potential for aerodynamic instability caused by its engine may be inappropriate for passenger aircraft. However, he does not think it is a bad design because the MCAS fixes the pitch up problem. As R. John Hansman, a professor of aeronautics at the Massachusetts Institute of Technology, told me in a March 28 interview, As I understand it, at high angles of attack the Nacelles -- which are the tube shaped structures around the fans -- create aerodynamic lift. Because the engines are further forward, the lift tends to push the nose up -- causing the angle of attack to increase further. This reinforces itself and results in a pitch-up tendency which if not corrected can result in a stall. This is called an unstable or divergent condition. It should be noted that many high performance aircraft have this tendency but it is not acceptable in transport category aircraft [emphasis mine] where there is a requirement that the aircraft is stable and returns to a steady condition if no forces are applied to the controls. In an April 2 interview Hansman emphasized that Boeing's installation of the MCAS system "fixes the pitch up problem. It is not a bad design." Boeing is proposing a fix to the MCAS which would require that both AOA sensors deliver similar readings -- they must be within 5.5 degrees -- before triggering the MCAS to tip down the nose. Boeing's fix will limit how sharply the MCAS can tip the nose down -- to no more than flight crew can counteract by pulling back on the control column in the cockpit. What's more, the fix would only allow the MCAS to tip down the nose once, rather than repeatedly -- as the current version does -- thus making it easier for pilots to recover, according to Newsy. Hansman suggested that AOA sensors could fail for many reasons including, "Electrical failures such as a short circuit, mechanical failures, a bird strike, icing, software, and/or a maintenance error." He pointed out that "triple redundancy" is standard safety practice for flight critical systems but the MCAS is exempt from this since it's not flight critical. As he explained [There is a fairly low risk that both AOA sensors would fail for the same reason. However,] one of the issues is if one has failed it can be difficult to determine which is correct. In flight critical applications where the airplane cannot fly without the sensor (not the case here as the airplane can continue to fly) it is standard practice to have triple redundancy. This is not always a third identical sensor but sometimes something that can be the tiebreaker. Last week Boeing faced skepticism as its executives tried to calm things down. According to the Washington Post, "They tried to sell a skeptical community of pilots, regulators and airline representatives on the idea that the new software would allay their concerns related to the MCAS system - even as they emphasized that the causes of the two crashes had not yet been firmly established." Peter Lemme, a former Boeing engineer, told the Post that he was glad that Boeing plans to disengage MCAS if the sensors send different signals. While newer Boeing jets have three AOA sensors, Lemme pointed out, the 737 MAX only has two. "If one's wrong, you can't take the average of two, and you can't use the good one, because the computer doesn't know which one is right," Lemme told the Post. Hansman told the Post, "Right now, we know what we are worried about. One of the challenges though is, when you start messing around with software, you have to make sure you haven't created some other problem or failure." But Hansman told me that the problems will ultimately be fixed. There is a standard testing and software validation and verification process that all flight control software must go through. My understanding is that this is in progress. The 737 MAX crashes have not helped [Boeing's reputation] but this is always the case when there is an accident. This case is not dissimilar to the initial problems with the A320 when it initially entered service. Boeing must get the improved software and training material approved by the FAA, EASA and Canadians and get the airplane flying again. There is not a fundamental problem in the design of the aircraft.

Faulty 737 Sensor From Lion Air Crash Linked to U.S. Repair Shop By Alan Levin and Harry Suhartono A faulty sensor on a Lion Air 737 Max that's been linked to the jetliner's deadly crash last October and a harrowing ride the previous day was repaired in a U.S. aircraft maintenance facility before the tragedy, according to investigative documents. Accident investigators in Indonesia, home of Lion Air, and the U.S., where Boeing Co., the plane's manufacturer, is based, have been examining the work that a Florida repair shop previously performed on the so-called angle-of-attack sensor, according to briefing documents prepared for Indonesia's parliament. Erroneous signals from that sensor triggered the repeated nose-down movements on the Oct. 29 flight that pilots struggled with until the jet plunged into the Java Sea, killing all 189 people aboard, according to a preliminary accident report by Indonesian investigators. The Lion Air crash and a similar one about five months later involving an Ethiopian Airlines 737 Max together prompted the grounding of Boeing's best-selling jet March 13 and touched off a global rebellion against U.S. aviation regulators. Investigators have focused on the sensor's role in the two disasters. Documents obtained by Bloomberg show the repair station XTRA Aerospace Inc. in Miramar, Florida, had worked on the sensor. It was later installed on the Lion Air plane on Oct. 28 in Bali, after pilots had reported problems with instruments displaying speed and altitude. There's no indication the Florida shop did maintenance on the Ethiopian jet's device. The Indonesian National Transportation Safety Committee is seeking data "from repair station in Florida" where the unit was worked on, the investigative agency said in a briefing to parliament last November and contained in a presentation. "Our thoughts and condolences are with all those who have lost loved ones in the recent 737 Max 8 accidents," XTRA Aerospace, a unit of Wencor Group LLC, said in a written statement. The company, it said, "is fully committed to supporting any investigations into this matter." Nurcahyo Utomo, lead investigator at the Indonesia NTSC, said the U.S. National Transportation Safety Board was conducting a review of the work performed on the sensor, but hasn't yet reported back on its findings. The sensor was made by Rosemount Aerospace Inc., of Minnesota, a subsidiary of United Technologies Corp. United Technologies declined to comment, citing the investigation. The sensor involved in the crash wasn't working from the time it was installed, according to the NTSC's preliminary report on the accident. Angle-of-attack sensors, which operate like a wind vane on the side of a jet, are designed to show how air is flowing relative to where the nose is pointed and alert pilots of a too-steep climb that could result in an aerodynamic stall. In the case of the Lion Air flights, the left-side sensor was showing the nose pointed about 20 degrees higher than was actually the case. It was that erroneous reading that caused an anti-stall computer system to assume the plane was in danger of losing lift and to repeatedly try to push down the nose on the final flight and the one that preceded it, according to the preliminary report that cited information from the plane's crash-proof data recorder. XTRA Aerospace is certified by the U.S. Federal Aviation Administration to perform repairs on multiple Boeing and Airbus SE models, according to its website. U.S. teams assisting the Indonesian investigation reviewed the work by the company to ensure that there weren't additional angle-of-attack sensors in the supply chain with defects, said a person familiar with the work. They didn't find any evidence of systemic issues on other sensors the company may have worked on, said the person, who wasn't authorized to comment on the work and asked not to be identified. Representatives of the NTSB, which is assisting Indonesia and Ethiopia in their crash probes, and the FAA, which is also participating, said they couldn't comment on a foreign accident investigation. A spokesman for Lion Air didn't respond to a request for comment left after business hours. Much of the concern by regulators and lawmakers after the Lion Air and Ethiopian Airlines crashes has focused on Boeing's design of the Maneuvering Characteristics Augmentation System, or MCAS, which was programmed to push down a plane's nose to help prevent aerodynamic stalls in some situations. But the preliminary report by Indonesia on the Lion Air crash shows that maintenance and pilot actions are also being reviewed. Repair Stations It's common for licensed repair stations to overhaul older parts so they can be resold, said John Goglia, a former member of the NTSB who earlier worked as an airline mechanic. Airlines can save money buying used parts and U.S. regulations require that the parts meet legal standards, Goglia said. If the sensor was repaired at XTRA Aerospace, "it would have to go through what the manual says to overhaul it," he said. "That means all the steps." The Indonesian preliminary report doesn't say what went wrong with the device but indicates that the plane's maintenance is a subject of the investigation. Even if it was improperly repaired or damaged in transit, the procedure for installation on the plane should catch any problems with the device, according to Charles Horning, chairman of the Department of Aviation Maintenance Science at Embry-Riddle Aeronautical University in Daytona Beach, Florida. "There would definitely be a return-to-service test to verify the installation," Horning said. "That would be the goal of the test, provided the test was done properly." When Goglia was a mechanic working on the 737 and other models, there was a procedure to move a new angle-of-attack sensor on the side of the plane and then check to see if readings in the cockpit were correct, he said. With today's electronic cockpits, mechanics would probably use a testing device that plugs into a computer system, he said. So far, it isn't clear why that required test didn't identify that the part wasn't functioning properly. The 737 Max that crashed in Ethiopia on March 10 also apparently had issues with the same type of sensor, which triggered a safety system on the plane that was driving down the plane's nose, according to people familiar with the accident. In that case, investigators are still attempting to locate one of the sensors to help determine why it malfunctioned, the people said. A preliminary report on that crash has not yet been issued and it could not be learned if the sensors had been previously repaired. Ethiopian Airlines Chief Executive Officer Tewolde GebreMariam has said there were no indications of maintenance issues before the flight.