Don Hudson

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Everything posted by Don Hudson

  1. TWO great-grandbabies?! How wonderful for you, Greg! Please say hello to your son & family for us. We have 3 GB's, 4, 2 & 4mo...we're often a hundred-and-an-eighth in coloring books, toys & 95-110db these days - ! Yes, the Neo...never understood the switch to a 1966 cable-&-pulley bread-and-butter type. I hope it works out for Boeing, and all the airlines that trusted and bought the airplane, but truly, it's an organizational & design/engineering lesson that never should have needed learning.
  2. Hi Greg; The splash-screen seen here in the link to the video posted by Jaydee is a clear illustration of the change in the engine/cowling arrangement, (a "btw", IEEE is a technical/profession/engineering association of which the gentleman who wrote the article is a member.) From the article: The last statement about the raised thrust line being the cause of the pitch up does not make sense. A thrust line that is closer to the longitudinal centerline of the fuselage does not increase force, it reduces it, so the statement is wrong right away without examining the actual design. The higher thrust line is not the reason MCAS was required. It is stated that the increased area of the engine cowlings providing an increase in lift at higher AoA's. This lift came just at the point where the older Boeings would be providing a heavier control column feel to the pilots, which certification standards, (CFR 25.173, I have seen quoted, pasted below), required. On the MAX, as speed reduced and the stall AoA was approached, a certain, required "pull" on the control column was not evident, so Boeing used the MCAS solution to provide this additional pull, which was necessary if the single B737 "type" was to be retained. They just don't appear to have done an "FMEA" when designing/building the system. MCAS action is intermittent, and if the trim wheels are seen rotating right after takeoff, it's the same as STS, (Speed Trim System) operation which is designed to force the pilot to trim out the artificial-feel forces as speed increases. Since the late 60's, we've been trained to recognize a runaway stabilizer as a continuous event, not an intermitent one with "intervals" of operation, which do not raise awareness, signal danger or provide a hint of what's actually happening, particularly when the crew is trying to determine why the stick shaker is activated and the airspeeds appear unreliable. Cheers as always, Greg!
  3. blues, re, "Interesting scrape marks.", yes, and also on the corner of the aileron, perhaps while it was full-down?...(brrrrrr). I have had the experience, once, of "running out of aileron" in a cross-wind in YYC, (A320) while the airplane kept rolling. It would be at the point where the airplane was likely in Direct Law, and I suspect this A321 was in the process of entering Normal Law...I'd have to get out the books. Oh,...wait,...
  4. It's not possible to know/predict the chances of that happening, but the drill is to hold the trim wheel & re-trim to neutral and continue to trim using the manual trim wheels as required.
  5. Both AoA sensors are used by the FCCs on alternate flight legs. The switch between left & right is accomplished through WoW sensing. One hopes the change includes some resiliency in a brittle system that breaks quickly and badly and instead fails gracefully, permitting crews time to assess what kind of runaway they're dealing with - continuous, or by 5" intervals which mimicks STS behaviour after lift-off. Along with comparison software that stops just the MCAS with an AoA disagreement of say, > 5°, one hopes there is clarity for crews on what the cut-off switches actually do. I believe they're both shut off now in the Runaway drill?
  6. j.k., agree with your comments. Also, at time 2:56, the video misleads viewers on the fundamental reason for the existence of MCAS on the MAX. Quote: "Except, moving the engines up on the 737 had a side effect. When the 737 was at full thrust, like during takeoff, the nose tended to point too far upward which can lead to a stall. This was a problem because these planes were supposed to behave like the old ones." end quote. They show the reason for the engine arrangement on the MAX quite well, but the statement regarding thrust & stalling at takeoff defies physics - moving the thrust line higher and thus closer to the longitudinal center of the fuselage, (or just above the floor-line) reduces, not increases, the effect of thrust line. The reason for MCAS is, the increased cowling area for the LEAP engine produced sufficient lift so as to render too-light a response when the a/c was nearing entry to the stall, (discovered in early flight tests). The reduced 'feel' of the CC did not conform to design standards under which the type was certified (in 1966). To be certifiable under the same type, it had to be demonstrated that the MAX had the same response as all previous B737s. Keeping same type was crucial to the sale of the aircraft. MCAS, which produced the required "heavier" control feel was Boeing's solution. This is all simplified I know. The false statement in the video invites an incorrect conclusion regarding the stall warning/stick shaker at takeoff on both accident aircraft, which occur for entirely different reasons to do with the left AoA sensor and possibly the left FCC.
  7. There is lots of scaffolding, meaning renovations were taking place.
  8. A manned giant six-engine aircraft with the world’s longest wingspan – surpassing Howard Hughes’s infamous Spruce Goose – took off from California on its first flight on Saturday. The twin-fuselage Stratolaunch jet lifted off from Mojave air and space port and climbed into the desert sky 70 miles north of Los Angeles. It successfully landed two hours later. The aircraft is designed to carry as many as three satellite-laden rockets under the centre of its enormous wing, which stretches 385ft, or 117 metres.
  9. Okay, there it is, confirmed, many thanks thinair.
  10. Seattle Times With close industry ties, FAA safety chief pushed more delegation of oversight to Boeing April 14, 2019 at 6:00 am By Dominic Gates Seattle Times aerospace reporter In 2012 the Department of Transportation’s Inspector General sent investigators to interview Federal Aviation Administration (FAA) technical staff in Renton, where engineers working under manager Ali Bahrami were responsible for certifying new planes developed by Boeing. The investigation substantiated employee allegations that FAA managers did not always support efforts by their technical experts to ensure Boeing complied with safety rules. It found “a negative work environment” where safety engineers feared retaliation “for attempting to hold Boeing accountable.” Now, two fatal crashes of Boeing’s 737 MAX have brought new scrutiny to the close-knit relations between the regulatory agency and the industry, to the FAA’s practice of delegating most safety analysis for new Boeing airliners to Boeing itself, and to shortfalls in the FAA’s final oversight role. With the MAX crisis jolting public faith in both Boeing and the FAA, Bahrami, now the executive at FAA headquarters in Washington D.C. specifically tasked with ensuring aviation safety, faces the daunting task of restoring confidence in his agency and in the process of certifying aircraft as safe. Hank Krakowski, former chief operating officer at the FAA, says, “Ali, coming from the certification branch in Seattle, is uniquely qualified to manage through this current situation.” But Michael Collins, a just-retired aerospace safety engineer who worked under Bahrami here, sees him as representing what’s gone wrong at the FAA. “He helped foster a culture among management in Seattle of delegating more than the FAA technical specialists were comfortable with,” said Collins. “When the FAA’s safety engineers had an opinion different from Boeing’s, he tended to side with Boeing.” Personifying tight FAA/industry relations Bahrami, 64, was born in Iran and came to the U.S for his education not long before Ayatollah Khomeini’s 1979 revolution. That year, having already earned a B.S. degree in engineering, he completed his M.S. at the University of Michigan and like many educated Iranian exiles decided not to return to his newly theocratic homeland. Instead, he took a job as an engineer with Douglas Aircraft in southern California, where he spent 10 years. Bahrami joined the FAA as an engineer in 1989, then rose to become in 2004 manager of the Transport Airplane Directorate in Renton, which oversees the safety of the operating fleet of U.S. commercial aircraft as well as the certification of new airplane models. During his tenure in Renton, Bahrami spearheaded efforts to delegate more inspection and certification work to industry, and specifically to outsource much of the safety analysis of new Boeing jets to Boeing itself. In 2013, Bahrami made a move reflecting the tightly intertwined relationship between regulator and industry. Just months after overheated batteries in flight caused the worldwide grounding of Boeing’s recently introduced 787 Dreamliner — a jet that Bahrami had shepherded through certification — he left the FAA for a lucrative lobbying job as a vice president of the Aerospace Industries Association,representing the big U.S. aerospace companies. That fall, testifying for the trade group before the House Subcommittee on Aviation, he painted the regulatory process as too slow and asked for changes to make it “more responsive to industry.” “We urge the FAA to allow maximum use of delegation,” Bahrami told Congress, now wearing an industry hat. “It would be detrimental to our competitiveness if foreign manufacturers are able to move improved products into the marketplace more quickly.” Then in 2017, he returned to the FAA executive ranks at just one level below the top job: Based at FAA headquarters, he’s now associate administrator for aviation safety, overseeing 7,200 employees and a budget of $1.3 billion. Former National Transportation Safety Board (NTSB) chairman Jim Hall succinctly summed up his view of Bahrami: “He’s been the agent for Boeing’s self-certification.” Bahrami, in emailed responses to questions, defended the delegation of safety analyses to Boeing and other private companies, and disputed Hall’s characterization. “Delegation is not self certification,” he said. “Our staff remains engaged throughout the certification process.” The U.S. aviation system, he insisted, “has never been safer.” Boeing controls certification Today’s reality is that when Boeing designs a new airplane, almost all the hands-on safety evaluations and tests are done by employees of Boeing or Boeing’s suppliers who are authorized to represent the FAA. These Authorized Representatives (ARs) file written documents that are then evaluated for compliance and signed off by FAA technical specialists. A Seattle Times investigation published last month showed that the safety analysis of a new flight control system on the 737 MAX that played a major role in the fatal crashes of a Lion Air jet last October and an Ethiopian Airlines jet last month was done entirely by Boeing. In addition, FAA engineers complained of being asked to delegate even more of the work to Boeing than originally agreed and of a constant schedule pressure during MAX certification. They said they were often given insufficient time to finish the evaluations — which in that case were sometimes signed off not by the technical staff but by managers or even just delegated back to Boeing for a final decision. In the case of the MAX’s suspect flight control system — called Maneuvering Characteristics Augmentation System, or MCAS — as a result of flight testing in the final year of certification, Boeing made significant changes to how it worked, including in certain circumstances increasing by a factor of four the system’s authority to move the horizontal tail so as to push down the nose of the plane. Those changes were never communicated back to the FAA technical staff, who had seen only a system safety analysis prepared before the changes. Drawing on Boeing’s expertise As the 2012 Inspector General (IG) investigation indicates, there was constant tension throughout Bahrami’s tenure as FAA boss in Renton between the agency’s technical staff, who wanted stringent application of the safety regulations, and managers who pressed for more speed and ever more delegation to Boeing. Mike McRae, a former senior aerospace engineer at the local FAA office, retired in 2013, a month before Bahrami left for his four-year stint working for industry. McRae said he retired unhappy with the direction of the safety agency and management’s lack of support for technical staff. He described Bahrami as a very capable bureaucrat who merely implemented the policy of increased delegation that was pushed from FAA headquarters. When Bahrami came in as boss, the policy was already firmly in place, mandated by Congress under heavy lobbying from Boeing and other giant aerospace companies. “He was a product of that culture,” said McRae. “He was inclined to delegate more. He thought we had to get the companies to take more responsibility for safety.” “That’s not irrational,” he said. “Delegation is an unfortunate necessity. You can’t fund an old-school regulatory FAA.” But McRae added, “I personally think they took it too far.” Bahrami himself argued, both from inside the FAA and when he spoke for industry, that there’s no alternative to delegation. The FAA has only about 1,300 personnel in its certification offices around the country, compared to the 56,000 engineers at Boeing. At a 2013 NTSB hearing after the 787 was grounded due to overheating lithium-ion batteries, Bahrami testified that he had only 20 to 25 staff working on the jet’s certification, so the FAA had to rely on 950 Boeing ARs to oversee and approve the detailed work. FAA personnel who certified the 787 never visited the battery manufacturer in Japan nor the company in France that designed the surrounding battery system. Boeing ARs handled all of that. And two IG audits have turned up shortcomings in the broader delegation process. An audit in 2011 found 45 instances between 2005 and 2008 where the agency had not carefully reviewed certification plans in advance, including one plan that didn’t comply with the regulations governing aircraft flight controls. A 2015 audit revealed that the previous year the agency had performed direct oversight of only 4 percent of the ARs conducting certification work on behalf of the FAA at aerospace suppliers. Bahrami co-chaired an extensive review of the airplane certification process in 2012. Tellingly, he was the only FAA representative on the review committee along with eight representatives of industry. The co-chair was Christine Thompson, a senior manager of Boeing’s airplane certification organization. That review recommended that because “the FAA has limited capacity,” it should “maximize delegation to the greatest extent.” A year later, now testifying for the industry, Bahrami told the House committee that due to lack of resources and budget the FAA simply cannot perform all the technical audits required to certify planes as safe. “Expecting FAA to keep pace with industry … is not in the realm of possibilities,” he said. Answering questions this month via email Bahrami said that this delegation of work to industry “enables regulators to leverage expertise at manufacturers’ facilities.” He added that the shortage of engineers throughout the aviation industry means the public sector must compete with the private sector in attracting talent. “Given the complex nature of today’s aviation products, it is virtually impossible for regulators to have all necessary expertise in every FAA office throughout the country, especially when global manufacturing models continue to evolve and grow,” Bahrami wrote. Mo Yahyavi, a former top executive at Boeing who ran the 747-8 program while that big jet was being certified in 2010, said Bahrami came with his team and toured the Everett production line as the test planes were being built, to verify and validate Boeing’s work on the design and testing. “I really was impressed with the guy as a hands-on person and trustful,” said Yahyavi. Earlier in his career, Yahyavi was himself designated an FAA representative at Boeing specializing in propulsion systems, and was given extra training for that role in how to interpret and define how the jet’s software worked with its mechanical systems. He said ARs at Boeing all have such specialized expertise. “There’s no way a certification organization like the FAA can understand and verify and validate everything by itself. They depend on the manufacturer’s engineers.” “The system was working,” Yahyavi concluded. “I wouldn’t change anything.” The gold standard of air safety Until the MAX crashes, regulation of aviation safety in the U.S., where 2.6 million passengers fly every day, has been the model for every other country. The last commercial passenger airplane lost in a crash in U.S. airspace was 10 years ago. In the decade since, airlines have flown 7.4 billion passengers safely to their destinations on 90 million U.S.-regulated flights with exactly one passenger death: on a Southwest Airlines 737 last year when an engine disintegration in flight blew out a window. That’s a remarkable record, not even closely approached by any other form of transportation. Former NTSB chair Hall believes the historically high level of air safety is based on years of experience and care, that’s now at risk from excessive delegation to industry. He points to the Volkswagen emissions scandal as evidence that “greed drives industry to do things that do not benefit society.” And he’s not impressed by Bahrami’s argument that the FAA doesn’t have the resources. “I have a hard time understanding anyone who sells increased industry participation by essentially saying that the agency he represents is incapable of doing its job,” said Hall. “Safety depends on checks and balances,” he added. “When you don’t have the checks in place, things get out of balance.” In the wake of the two MAX crashes, Congress has been scrambling to hold hearings and demand accountability. The House Committee on Transportation and Infrastructure has requested records from Boeing and the FAA as part of its investigation into the 737 MAX certification process. And yet Congress itself has backed that process, with prodding from the industry. The latest legislation, the FAA Reauthorization Act of 2018, passed into law just weeks before the Lion Air crash last October, requires the FAA to “delegate fully” unless the head of the agency determines there is specific public safety reason to limit the delegation. In such a case, the FAA is instructed to work with the industry partner to return it to full authority. Furthermore, if any certification glitch occurs to slow down an airplane program, the FAA must automatically elevate the issue to management and resolve it within a time period agreed with the manufacturer. Hall says the reason for such provisions is straightforward: The heavy lobbying of Congress by Boeing and other aerospace companies. U.S. Transportation Secretary Elaine Chao, the ultimate boss of the FAA, is the wife of Republican Senate Majority Leader Mitch McConnell. But the influence is bipartisan. In the late 1990s, the deputy FAA administrator and for a time acting administrator was Linda Hall Daschle, wife of U.S. Senator Tom Daschle, then Democratic Senate Minority Leader. Linda Daschle left the FAA to work as an aerospace lobbyist. Former FAA chief operating officer Krakowski defends the role of manufacturers in ensuring the safety of their own products. While there is always commercial pressure to meet schedules, he said, jet manufacturers face a more existential pressure to make their airplanes safe. “If you don’t, the ramifications for Boeing and the airlines are evident right now” with the MAX crisis, he said. “I think there is a moral driver (to protect passengers) that Boeing does understand, but also, from a business point of view, the consequences they are living with right now are an additional driver.” Yet somehow, this complex safety ecosystem failed on the MAX. Krakowski said that the missed flaws in the MCAS flight control system that seem to have caused both recent crashes mean something went wrong not only at Boeing and the FAA, but also at the major airlines, where the flight technical departments “typically know every nut and bolt on the airplane and how it should operate.” “All three own a piece of this. Nobody raised a hand and said, wait a minute, let’s talk more about this system,” he said. “I’m thunderstruck nobody caught this.”
  11. Gosh, I don't know what's acceptable anymore conehead. We are in a period of great flux. As my brother, an electrical engineer, says with a smile, "That's the wonderful thing about standards: there are so many to choose from." To me anyway, the Boeing manuals I have experience with are thin on information. The details of what a control or indicator actually does and how it works are absent. I think there is less than even pilot-NTK information but that's just my view. I know the reasons, one of which Boeing itself stated recently with regard to MCAS. So, for the 250 turns, I have two was a PPRuNe post on the Ethiopian thread, and the other was a site where someone was building their own flight-simulator and made the statement regarding "250 turns". Kip's mental filing cabinet may very well be functioning perfectly! One way or another, people will find things out, fill stuff in or, these days it seems to me, with increasing legitimacy, just make up the information they want or need. It's always best that original, formal sources, (the manufacturers, the regulator, etc.), share as much as they can when working in high-risk enterprises. Otherwise, trust in information, (and resulting behaviours) become an issue as we "choose" our standard then claim we've met it. Not a good way to do aviation, in my opinion.
  12. Yes, I think that's a reasonable notion. On turns of the wheel, I've read that it takes 250 turns to go from full NU to full ND, (17°), or 14.7 turns for one degree or 0.068° per turn. That is not verified in any manual to which I have access, but if it's that, one can understanding giving the method up and turning the system back on again. If it's 40-45 turns for 17°, then its just over a third-of-a-degree per turn. I suspect the mechanical advantage, (ratio of 1 turn to how much the stab moves) would be small and the wheel would be very difficult to move. As shown in the traces with the last two blips of trim, the Pitch Trim parameter moves so the CC trim switches worked, which I believe is evidence that the manual method would have worked but not fast and probably not easily. - they had a long way to wind the trim ANU at ~15 turns per degree. I don't know how units and degrees relate - and I could be using "degrees" when it might be "units". Again, there is no information in the AMM, the AOM or the FCTM.
  13. Hi Kip; Yep, got that, thanks. As I expressed in my previous post to Turbofan, “Main electric” would of course be the control column switches." But that illustrates why I wrote the full descriptions in red font in the original post of the article from AW&ST - the article uses the term "manual" when referring to the trim wheels but conflates the term "manual" when applied to the trim switches on the control column because they're manipulated by hand even as they are controlling an electrically-driven, (primary) trim system. edited to add: There is further confusion regarding manual & electric trim - it is claimed, (but without verifiable evidence yet) that the manual trim wheels could not be moved. One theory is, "HS stall due high loads on the trim mechanism due high airspeed". But the trim moved ANU when the crew used the CC trim switches, (indicating, along with MCAS input, that the cut-off switches had been moved back to their normal position). Manual trim using the wheels doesn't work but electric does? Why? On Woody's comment, yes, got that too but probably didn't express it very well. It makes complete/logical sense that if the trim has run away due MCAS and nothing was done until time had passed, then when the trim is cut off by the CUTOFF switches, it freezes the system with whatever trim was in prior to using the switches. That's why the NNC states to trim neutral then cut-off the trim, (but, and Woody makes this point), the FAA AD doesn't emphasize the highly-critical importance of trimming the pitch to neutral right away and then cutting off the trim system. That's the key of course, and I agree with Woody that the wording is weak and buried, but it isn't confusing - it's just obscured in all the blather of the FAA's original and subsequent ADs. This goes back to the absence of any information and therefore training for a system that controls the most powerful flight control on the aircraft which has the potential for loss of the aircraft under certain, previously-latent conditions.
  14. Hi Woody; Minor point, the Boeing FCOM wording is from the FAA Emergency AD's issued November 07, 2018 and December 21, 2018 as a revision to the AFM, (Airplane Flight Manual). It is obviously impossible to trim if the cut-off switches have been moved to CUT-OFF without trimming first, but the wording in the AD is to ensure neutral trim prior to doing so*. If I understand what you meant by, " manual trimming may be impossible ", I don't think trimming to neutral using the manual trim switches on the control column would be impossible purely due to high loads on the HS. Stabilizer 'blow-back' can occur with a "ball-screw" arrangement, (vice a screw-jack) but there are two brakes on the HS mechanism that are released whenever the electric trim or the manual-wheel trim is used. I believe that electric trim was available because there is slight HS movement concurrent with the last two blips of ANU electric trim, (resetting the MCAS which dutifully re-trims AND for ~6" resulting in the final dive). * There is no statement in the AD or the FCOM requiring that the procedures (in Fig.2 & the Runaway Stabilizer NNC) set out/referenced in the FAA AD are to be executed by memory. The FAA and Boeing leave it to individual airlines and crews to decide how to handle these procedures. Runaway stabilizer NNC: FAA AD revision: *
  15. The terms “manual trim” have been sources of confusion and Boeing’s FCOM hasn’t made it clearer. For the AW&ST article, when referring to trim, the author accompanies the term, "manual" with a description of which manual trim is being used, the control column switches or the center console trim wheels. Take a look at the AW&ST article, re-posted with descriptions of which "manual" trim is in use, (red font). The term "manual trim" is used in five places in which "switches" or "wheel" are not specified, and one place in which the Boeing’ runaway stabilizer checklist is referenced as, “control aircraft pitch attitude manually with control column and main electric trim as needed,”. “Main electric” would of course be the control column switches. I used red font in the original article below, clarifying what “manual trim” is being referenced. Apologies if it seems a bit pedantic. It was the only way I could get it clear in my own mind... So, yes, they could trim the aircraft manually using the control column switches until they used the cut-off switches. Why they couldn't use the manual trim wheels on the center console has not been determined, but one reason may be the rate at which these wheels change the revolution is about 0.07deg of HS trim, or, 1deg change using the wheels takes almost 15 turns.* Also, from what I have read, it's easier to rapidly turn the wheel, (handle extended), from the left seat than the right. This may have to do with simply being right or left handed. And yes, they could have used the manual (switches) trim right up to the end. This is verified by the albeit-tiny change, that the two manual-switch inputs by the crew changed the HS position. Full HS range using manual trim wheel = 17deg It takes 250 turns to go from stop to stop.
  16. From AW&ST; April 12, 2019 LOS ANGELES—As the investigation continues into the causes of the Mar. 10 Ethiopian Airlines Boeing 737 MAX accident, sources close to the probe say flight data recorder (FDR) data firmly supports the supposition that the aircraft’s left angle-of-attack (AOA) sensor vane detached seconds after take-off and that, contrary to statements from the airline, suggests the crew did not follow all the steps for the correct procedure for a runaway stabilizer. Detailed analysis of the FDR trace data shows that approximately six seconds after liftoff was signaled by the weight-on-wheels switch data, the data indicate the divergence in angle-of-attack (AOA) and the onset of the captain’s stick-shaker, or stall warning. Almost simultaneously, data shows the AOA sensor vane pivoted to an extreme nose-high position. This, says one source, is a clear indication that the AOA’s external vane was sheared off—most likely by a bird impact. The vane is counter-balanced by a weight located inside the AOA sensor mounting unit, and without aerodynamic forces acting on the vane, the counterweight drops down. The AOA sensor, however, interpreted the position of the alpha vane balance as being at an extreme nose-high angle-of-attack. With the stick shaker active, the trace indicates the crew pushed forward on the column to counteract what they believed were indications of potential approach to stall. The aircraft, now in level flight, also accelerated rapidly as its power setting remained at 94% N1 thrust used for take-off. This was followed by some manual trim inputs using the thumb switches on the control column. Seconds after speed advisories were heard, the crew raised the flaps. With the autopilot turned off, flaps up and erroneous AOA data being fed to the flight control computer (FCC), the stage was set for the MAX’s maneuvering characteristics augmentation system (MCAS) to activate. This is indicated by approximately 8-sec of nose-down stabilizer movement, which was followed by the use of manual trim on the control column. However, with the MCAS having moved the stabilizer trim by 2.5 units, the amount of manual nose-up trim using the control column switches applied to counteract the movement was around 0.5 units, or roughly only 20% of the amount required to correctly re-trim the aircraft. Because of the way the aircraft’s flight control computer P11.1 software worked, the use of manual trim using the control column switches also reset the MCAS timer, and 5 sec. later, its logic having not sensed any correction to an appropriate AOA, the MCAS activated again. The second input was enough to put in the full nose-down trim amount. The crew again manually counteracted with nose-up trim using the control column switches, this time offsetting the full amount of mis-trim applied by the latest MCAS activation. By then, some 80% of the initial MCAS-applied nose down trim was still in place, leaving the aircraft incorrectly trimmed. The crew then activated the stabilizer trim cutoff switches, a fact the flight data recorder indicates by showing that, despite the MCAS issuing a further command, there was no corresponding stabilizer motion. The aircraft was flying at about 2,000 ft. above ground level, and climbing. The crew apparently attempted to manually trim the aircraft, using the center-console mounted control trim wheels, but could not. The cut-out switches were then turned back on, and manual trim using the control column switches briefly applied twice in quick succession. This reset the MCAS and resulted in the triggering of a third nose-down trim activation lasting around 6 sec. The source says the residual forces from the mis-trim would be locked into the control system when the stabilizer cut-off switches were thrown. This would have resulted in column forces of up to around 50 lb. when the system was switched back on. Although this could have been reduced by manually trimming the aircraft using the center-console mounted control trim wheels, this did not occur, and the third MCAS activation placed the aircraft in a steep nose-down attitude. This occurred with the aircraft near its peak altitude on the flight—about 6,000 ft. The engines remained at full take-off power throughout the flight, imposing high aerodynamic loads on the elevators as the crew attempted to pull back on the columns. Vertical acceleration data also indicates momentary negative g during which the AOA sensor on the left side unwinds. This is seen as further validation of the theory that the external part of the alpha vane was detached as the apparent change in angle indication could only be explained by the effect of negative g on the counterbalance weight, forcing it to float up inside the sensor housing. In addition, the captain’s stick shaker also comes off twice in this final phase, further reinforcing the severed vane notion. The source indicates the crew appeared to be overwhelmed and, in a high workload environment, may not have followed the recommended procedures for re-trimming. Boeing’s stabilizer runaway checklist’s second step directs pilots to “control aircraft pitch attitude manually with control column and main electric trim as needed,” according to one U.S. airline’s manual reviewed by Aviation Week. If the runaway condition persists, the cut-out switches should be toggled, the checklist says.
  17. Boeing Expands MCAS Demos To Speed Lifting Of 737 MAX Grounding Apr 9, 2019 Guy Norris | Aviation Week & Space Technology Pilot feedback to the proposed software changes to the Boeing 737 MAX Maneuvering Characteristics Augmentation System (MCAS) flight-control law is positive, says Boeing. After demonstrations, pilots believe the potential for further flight-control problems from the system are a “nonissue,” the airframer says. However, despite the positive response from pilots to the upgraded control system and associated training package, Boeing is gearing up for a prolonged international effort to reinstate the grounded MAX fleet. The embattled company, which first unveiled the proposed MCAS changes to a group of certification authorities and airline pilots in Seattle on March 27, is embarking on a global campaign to convince regulators that the updates will be sufficient to enable the aircraft to return to service. The campaign encompasses a series of simulator demonstrations and briefings at multiple training sites throughout Europe, Asia and Australia and comes as Boeing attempts to handle a situation unprecedented in its history. Because the MAX was grounded first by China and other authorities around the world days before the FAA followed suit, the company says it is imperative to build support for an international caucus of regulators willing to reauthorize the MAX to return to flight. The FAA, which in past years would have taken a lead role in such an effort, is similarly shifting gears and is now working alongside a broader group of international regulators to adjudicate the case. The agency says it expects to receive Boeing’s final package of its software enhancement over the coming weeks. Meanwhile the FAA has set up a Joint Authorities Technical Review (JATR) to conduct a comprehensive review of the certification of the aircraft’s automated flight-control system. Chaired by former NTSB Chairman Christopher Hart, the JATR is comprised of a team from the FAA, NASA and international aviation authorities. Boeing, which on April 5 signaled a 19% production slowdown of its 737 line to ease the growing logjam of undelivered aircraft, is also providing more details about the changes to the MCAS functionality contained in the new P12.1 flight-control computer (FCC) software load that will replace the existing P11.1 software. Based on pilot reaction to date, the company says it is confident its software upgrade is certifiable. The briefings continue to emphasize that the MCAS, which was added to the speed-trim system to standardize handling qualities with those of the 737 Next Generation, is “not a stall-protection function and not a stall-prevention function,” says Mike Sinnett, Boeing Commercial Airplanes vice president of product development and future airplane development. “It is a handling-qualities function. There’s a misconception it is something other than that. “ Added to ensure a linear relationship between stick force per G, “speed trim is a function of airspeed, so if you’re going fast, it’s a low angle-of-attack (AOA), and if you’re going slow, it’s at higher AOA,” he notes. “The thing you are trying to avoid is a situation where you are pulling back and all of a sudden it gets easier, and you wind up overshooting and making the nose higher than you want it to be.” The updated MCAS is being demonstrated to pilots in MAX simulators around the world. Credit: Boeing Underscoring the difference between the speed-trim system on the 737 Next Generation (NG) and the MAX, Sinnett says: “Mechanically, on the NG there is a column cutoff switch that stops any automatic trim when the column is back to a certain spot. On the MAX, we still needed automatic trim when you got to that spot. MCAS differs from speed trim at elevated alpha because it bypasses that switch by design. To do that, it activates based on AOA rather than based on speed—which is what speed trim does. Speed trim is a function of airspeed, and MCAS is a function of angle-of-attack and Mach number, but it only triggers off AOA.” In the initial briefing sessions for pilots on March 27, “we didn’t talk specifically about either of the accidents, but we ran through MCAS scenarios,” says Sinnett. “From the accidents, we now know how MCAS can behave when there is an erroneously high AOA input, so we walked through scenarios where that could occur. We demonstrated those in the simulator.” In these sessions, pilots and regulators were able to interact via intercom and a big screen with Boeing pilots in the 737 MAX engineering cab. Following the sessions, “we went back to the classroom and said, ‘Here are the things that concern us most when we look at the scenario of the two accidents we just experienced,’” Sinnett says. “Upon reflection on what has occurred, it appeared the system could present a high-workload environment—and that’s not our intention. So we looked at changing the design to compare values from multiple AOA indicators to essentially eliminate the unintended trigger condition that causes MCAS to activate. “ Sinnett says pilots appear satisfied that the three main layers of protection now added to the MCAS will prevent any potential repeat of the circumstances involved in the Lion Air and Ethiopian Airlines accidents. “We answered a lot of questions during the discussion, and then we went back into the simulator and demonstrated a number of different scenarios to run against these changes,” Sinnett says. “And the most compelling thing is that the AOA failure case turns into a run-of-the-mill AOA failure case like you might have on any other airplane. We didn’t get any negative feedback. It was all very positive, and any of the pilots who got into the simulator and saw the before and after, it was like, ‘Yes, OK, this is now a nonissue.’” The first main layer of protection provided by the update is a cross-channel bus between the aircraft’s two FCCs, which now allows data from the two AOA sensors, or alpha vanes, to be shared and compared. AOA data continues to be fed from left and right vanes into their respective air data inertial reference units before being passed to the flight computers. However, the AOA data in both computers is now continuously compared. The change is made by software only and requires no hardware modification. “In a situation where there is erroneous AOA information, it will not lead to activation of MCAS,” says Sinnett. He underlines that the entire speed-trim system, including the MCAS, will be inhibited for the remainder of the flight if data from the two vanes varies by more than 5.5 deg. If an AOA disagreement of more than 10 deg. occurs between the sensors for more than 10 sec., it will be flagged to the crew on the primary flight display. The second layer of protection is a change to the logic in the MCAS algorithm that provides “a fundamental robust check to ensure that before it ever activates a second time, pilots really want it to activate,” says Sinnett. The change would have protected the system from continuing to activate in the case of the Lion Air accident, in which the left AOA vane was stuck in the 20-deg.-nose-high position. In that circumstance, the logic rechecked if the MCAS was required and, registering the apparent nose-high position from the errant vane, commanded more nose-down trim. “Now it sees you’re in the same spot, it says you’ve got a stuck vane and says, ‘I’m not going to activate again,’” Sinnett notes. “That’s assuming it will activate in the first place, which it won’t because one AOA vane with a high value won’t activate,” he adds. “When you do defense in depth, you have to artificially fail one layer to make sure you adequately design and test the next layer—so that’s what we had to do.” Explaining the background to the third layer of protection, Sinnett says: “We also made sure if the second layer of protection failed somehow in some weird way and allowed MCAS to activate multiple times, the system now ensures the sum total is command-limited.” The result is that the pilots always have maneuvering authority remaining with the control column. “Pilots will always have the ability to override—although they had that before in other ways, like with the trim switch, for example. But with the software update, the column itself will always provide at least 1.2g of maneuvering capability. So you don’t just have the ability to hold the nose level, you can still pitch up and climb.”
  18. Boeing will slow 737 production by one-fifth; no layoffs planned Seattle Times April 5, 2019 at 1:06 pm Updated April 5, 2019 at 5:55 pm By Dominic Gates Seattle Times aerospace reporter The two recent fatal crashes and subsequent grounding of Boeing’s 737 MAX have prompted the jet maker to sharply and quickly cut production in Renton from the current 52 airplanes per month to 42 per month, signaling that a return to flight isn’t expected soon. Boeing said it does not plan any layoffs due to the rate reduction, which begins in about 10 days. Managers are informing employees of the Renton 737 factory at meetings on Friday. “The 737 program will maintain current employment levels,” said Boeing spokesman Paul Bergman. “We’re adjusting the rate to accommodate the pause in deliveries. There’s no employment impact.” Boeing Chief Executive Dennis Muilenburg said the rate reduction will allow the company “to prioritize additional resources to focus on software certification and returning the MAX to flight.” The move will hurt Boeing’s cash flow this year, putting more pressure on the share price, which has dropped 9 percent since the second crash, Ethiopian Airlines Flight 302 on March 10. Boeing announced the news of the production-rate drop moments after the stock market closed Friday. About 12,000 people work at the Renton plant where the 737s are assembled. The plant now mostly produces the MAX model, with a fast-dwindling number of older-model 737s rolling off the line. In February, Boeing delivered 20 MAXs and just 14 older models. Boeing makes rate-change decisions like this only reluctantly, because the impact on suppliers is severe and the whole production system will be disrupted unless all the suppliers can act in unison. So Boeing typically changes the rate only when it knows it can maintain the new production pace for at least a year or so. In this case, Boeing is calling the rate reduction “temporary,” its extent dependent on how long the MAXs are grounded — which is unpredictable. However, the move suggests Boeing anticipates a prolonged grounding lasting months. Obstacles to resumption of flight include both technical fixes and regulatory approvals from a global community of aviation-safety agencies that have grown more skeptical of both Boeing and the U.S. Federal Aviation Administration (FAA). The 737 production system is such a well-oiled, efficient machine — it has gradually accelerated production from 27 jets per month 20 years ago to 52 per month today — that it can accelerate or slow down only in very carefully choreographed phases. Related FAA official tells senator that Boeing 737 MAX inspectors were ‘fully qualified’ Every rate increase requires a synchronized step up by the entire supply chain, whether it’s a company supplying tens of thousands of small fasteners or one delivering dozens of whole fuselages. It has to be meticulously planned so that raw materials and labor are in place to handle the extra work. Each step up means more money coming in, which is part of each supplier’s business plan many months ahead. This rate decrease will require suppliers to correspondingly step down, meaning a hit to their business as well as potential layoffs. Muilenburg said Boeing will “work directly with our suppliers on their production plans to minimize operational disruption and financial impact of the production rate change.” Hardest hit will be Spirit AeroSystems in Wichita, Kansas, which makes the complete fuselages for all 737s and sends them by train to Renton. Spirit must quickly adjust its own pace to build 10 fewer fuselages per month. Likewise, CFM International, which provides the new LEAP engine on the MAX, will have to deliver 20 fewer engines per month. But since CFM was struggling with the steep production ramp up of these engines, which are delivered to both Boeing and Airbus, the slowing of its pace may actually be a welcome chance to get back on track. Bergman, the Boeing spokesman, said that because of the complexity of the 737 supply chain, once the grounding is lifted, production in Renton will have to ramp back up “in a phased approach.” That could mean some months. It’s likely that once Boeing does get the go-ahead from the FAA and foreign regulators to begin flying the planes again, it will first ramp up to 47 jets a month and get that pace running smoothly before moving back up to 52 per month. And when it does resume deliveries of the MAX, it will take Boeing many months to catch up on the delayed deliveries to airlines. It may shuffle the delivery schedule to try to accommodate airlines that need their planes sooner, asking others to wait longer. Moving around the delivery schedule should be made easier because some airlines are now wavering on whether to defer or even keep their orders for the MAX. Some will want to hold off taking their airplanes until a successful re-entry into service has overcome anxiety among the flying public about the plane’s safety. A resumption of higher production will depend on how long it takes to get approval from the FAA and foreign regulators for Boeing’s proposed software fix to the MAX’s flight-control system and accompanying pilot training. “We’ll have to monitor as we go,” Bergman said. Other issues will also need addressed before the grounding can be lifted. The preliminary investigation into the Ethiopian Airlines crash last month revealed that it had essentially the same cause as the Lion Air crash in October: a failed angle-of-attack sensor that measures the angle between the wing and the oncoming airflow fooled the flight computer into thinking the plane was pitched too high and triggered a new automatic flight-control system that pushed the nose of the jet down repeatedly. But the sensors in the two accidents apparently failed in different ways. So in addition to the software update for its new Maneuvering Characteristics Augmentation System, or MCAS, Boeing will also have to find out how those sensors failed. Airlines must also be satisfied before the MAX can fly again. In an interview Thursday on NPR’s “All Things Considered,” Ethiopian Airlines Chief Executive Tewolde GebreMariam said he’s undecided on whether the carrier will stick with its Boeing order for 29 MAX airplanes. “Boeing and the FAA will have to convince us all, not only Ethiopian Airlines, but all the regulators, all the operators that have grounded the airplanes,” Tewolde said. “We will have to be convinced beyond reasonable doubt that the airplane is safe to be back on the air and then we will decide what to do with our orders.” CEO Muilenburg said Boeing is “coordinating closely with our customers as we work through plans to mitigate the impact” of the production cut. In a note to clients last month, Ron Epstein, an aerospace-industry analyst with Bank of America, estimated a three- to six-month grounding is likely. The 737s that continue to be built will still have to be parked all around the Puget Sound region until the grounding is lifted and deliveries resume. The news of the sharp rate reduction seems to place out of reach Boeing’s publicly stated goal of increasing 737 production later this year to 57 jets per month. That will have a competitive impact because Airbus is ramping up to build 60 single-aisle jets per month by mid year, including its rival A320 family of jets and its new A220 models. It has ambitions to hike that to 63 per month in subsequent years. The higher rate allows Airbus to offer airlines earlier delivery slots. The main barrier to increasing its production has been the availability of LEAP engines, so the slowdown in supplying those engines to Boeing may even help Airbus ramp up more quickly. On Friday, Bergman said he has “no information” about any change to the plan to ramp up to 57 per month. But Boeing cannot really plan for that without more clarity on when the grounding might be lifted.
  19. No, probably not. It's a screwjack and can't easily be back-driven by stabilizer forces. Flaps driven by hydraulic cylinders, (vice motors) can blowback but not flaps driven by screwjacks. Edit to add: The AoA sensor is physically capable of reading +/- 20°, (AMM test procedure), so 1) the AoA was damaged on takeoff, (appears normal - trails to '0' - until liftoff), or 2) the AoA sensor is working correctly and the incorrect data is being generated downstream, possibly by the FCCs. What, statisically, fits better, an errant AoA sensor or an errant box downstream? In the million-plus hours that have been flown by the MAX since 2017, why two incidents of incorrect AoA data within months of one another?
  20. From D.P. Davies, "Handling the Big Jets", (2nd ed., 1970): Obviously he treated the trimmable stabiizer with great seriousness and extraordinary respect for it's capable (and lethal) power. I would like to have been able to hear what Davies would say regarding the present circumstances.
  21. Ethiopian Airlines Pilots Initially Followed Boeing’s Required Emergency Steps to Disable 737 MAX System Details of Ethiopian crew’s actions gleaned from preliminary black-box data People from various hamlets and villages pay respects to the 157 victims who perished in the crash of Ethiopian Airlines flight 302. Photo: Jemal Countess/Getty Images By Andy Pasztor and Andrew Tangel April 2, 2019 11:47 p.m. ET Pilots at the controls of the Boeing Co. 737 MAX that crashed in March in Ethiopia initially followed emergency procedures laid out by the plane maker but still failed to recover control of the jet, according to people briefed on the probe’s preliminary findings. After turning off a flight-control system that was automatically pushing down the plane’s nose shortly after takeoff March 10, these people said, the crew couldn’t get the aircraft to climb and ended up turning it back on and relying on other steps before the final plunge killed all 157 people on board. The sequence of events, still subject to further evaluation by investigators, calls into question assertions by Boeing and the U.S. Federal Aviation Administration over the past five months that by simply following established procedures to turn off the suspect stall-prevention feature, called MCAS, pilots could overcome a misfire of the system and avoid ending in a crash. The pilots on Ethiopian Airlines Flight 302 initially reacted to the emergency by shutting off power to electric motors driven by the automated system, these people said, but then appear to have re-engaged the system to cope with a persistent steep nose-down angle. It wasn’t immediately clear why the pilots turned the automated system back on instead of continuing to follow Boeing’s standard emergency checklist, but government and industry officials said the likely reason would have been because manual controls to raise the nose didn’t achieve the desired results. After first cranking a manual wheel in the cockpit that controls the same movable surfaces on the plane’s tail that MCAS had affected, the pilots turned electric power back on, one of these people said. They began to use electric switches to try to raise the plane’s nose, according to these people. But the electric power also reactivated MCAS, allowing it to continue its strong downward commands, the people said. The same automated system, also implicated in a 737 MAX crash in Indonesia in late October, has become the focus of various congressional and federal investigations, including a Justice Department criminal probe.Boeing announced it is making changes to how a new a stall-prevention system works on its new 737 MAX aircraft — the same model jet involved in the Ethiopian Airline s crash. WSJ’s Jason Bellini reports. The latest details are based on data downloaded from the plane’s black-box recorders, these people said. They come as Ethiopian investigators prepare to release their report about their preliminary conclusions from the accident, anticipated in the coming days. Investigators probing the Oct. 29 crash of Lion Air Flight 610 believe erroneous data from a single sensor caused the MCAS system to misfire, ultimately sending the plane into a fatal nose-dive and killing all 189 people on board. Some of the same key factors were at play in the Ethiopian crash, according to people briefed on the details of both crashes. After the Lion Air accident, Boeing and the FAA issued bulletins to 737 MAX operators around the world reminding them of the existing procedure pilots are trained to follow should the plane’s flight-control system go haywire and mistakenly push down the nose. Those are the steps the Ethiopian pilots initially took months later, these people said. That procedure works to disable the new MCAS, much like another flight-control feature on earlier 737 models, by cutting power. The plane maker and FAA’s bulletins highlighting that safeguard were often mentioned after the Lion Air accident when U.S. aviation industry officials vouched for the aircraft’s safety. U.S. Investigators looked at debris from the crash in Bishoftu, Ethiopia, on March 12. Photo: Jemal Countess/Getty Images Boeing Chief Executive Dennis Muilenburg noted the procedure in a Nov. 13 television interview when asked about information given to pilots. “In fact, that’s part of the training manual,” Mr. Muilenburg said on Fox Business Network, adding the manufacturer was confident in the plane’s safety. “It’s an existing procedure so the bulletin we put out…pointed to that existing flight procedure.” At a briefing for reporters last week, a Boeing official noted investigations of both crashes were continuing but didn’t comment about specifics when he outlined a coming software fix for the MCAS system and related training changes. The revised system will rely on two sensors, instead of one as originally designed, to prevent erroneous data triggering it. The system will now be designed to make it less aggressive and allow pilots more control over it, according to previous Boeing and FAA statements. Mike Sinnett, Boeing’s vice president of product strategy, said last week the plane maker had “complete confidence that the changes we’re making would address any of these accidents.” Between Two Deadly Crashes, Boeing Moved Haltingly to Make 737 MAX Fixes The Final Minutes of Ethiopian Airlines’ Doomed Boeing 737 MAX How Boeing’s 737 MAX Failed The software fix could come as soon as mid-April, according to a person briefed on that issue, but further tests are needed before regulators can approve and mandate it so the grounded fleet can return to service. Another person close to the process, however, said final FAA reviews and tests could take up to six weeks. After that, it could take months longer for some overseas regulators to review and certify the fix for aircraft they oversee. Activation of MCAS and a related pilot alert, which warns pilots of an impending aerodynamic stall, had been reported previously regarding the Ethiopian crash. But in the wake of the tragedy, Boeing, the FAA and Ethiopian authorities leading the probe have refrained from making any comments about whether the crew followed Boeing-sanctioned procedures to cope with the emergency. Going forward, aviation experts, regulators and pilots debating the relevant safety issues will have to consider the implications that while the pilots did take such steps in the beginning, those apparently didn’t work as expected likely due to the plane’s speed, altitude and other factors. Eventually, the crew veered to other, nonstandard procedures that made their predicament even worse. Another issue likely to be raised by the preliminary Ethiopian report is why a single sensor malfunctioned or somehow may have been damaged shortly after takeoff—touching off the deadly chain of events. Write to Andy Pasztor at and Andrew Tangel at
  22.,1,t0dL8-wyHZuc8SdqNGXe2VZHHI3GpMNR7u0WUV5qe7ejgQyQBhwz8Wl6jeoQnObVrDxKVV8ACzYHfVJ-UE5M3c7ghBKHZH7u8KTF2WowdACxfYg-a0ca&typo=1 The emerging 737 Max scandal, explained It’s more than bad software. By Matthew Mar 29, 2019, 9:10am EDT SHARE An employee walks down a stairway leading to a Boeing 737 MAX airplane on March 14, 2019, in Renton, Washington. Stephen Brashear/Getty Images Boeing executives are offering a simple explanation for why the company’s best-selling plane in the world, the 737 Max 8, crashed twice in the past several months, leaving Jakarta, Indonesia, in October and then Addis Ababa, Ethiopia, in March. Executives claimed on March 27 that the cause was a software problem — and that a new software upgrade fixes it. But this open-and-shut version of events conflicts with what diligent reporters in the aviation press have uncovered in the weeks since Asia, Europe, Canada, and then the United States grounded the planes. The story begins nine years ago when Boeing was faced with a major threat to its bottom line, spurring the airline to rush a series of kludges through the certification process — with an underresourced Federal Aviation Administration (FAA) seemingly all too eager to help an American company threatened by a foreign competitor, rather than to ask tough questions about the project. The specifics of what happened in the regulatory system are still emerging (and despite executives’ assurances, we don’t even really know what happened on the flights yet). But the big picture is coming into view: A major employer faced a major financial threat, and short-term politics and greed won out over the integrity of the regulatory system. It’s a scandal. The 737 versus 320 rivalry, explained There are lots of different passenger airplanes on the market, but just two very similar narrow-body planes dominate domestic (or intra-European) travel. One is the European company Airbus’s 320 family, with models called A318, A319, A320, or A321 depending on how long the plane is. These four variants, by design, have identical flight decks, so pilots can be trained to fly them interchangeably. The 320 family competes with a group of planes that Boeing calls the 737 — there’s a 737-600, a 737-700, a 737-800, and a 737-900 — with higher numbers indicating larger planes. Some of them are also extended-range models that have an ER appended to the name, and, as you would probably guess, they have longer ranges. Importantly, even though there are many different flavors of 737, they are all in some sense the same plane, just as all the 320 family planes are the same plane. Southwest Airlines, for example, simplifies its overall operations by exclusively flying different 737 variants. Both the 737 and the 320 come in lots of different flavors, so airlines have plenty of options in terms of what kind of aircraft should fly exactly which route. But because there are only two players in this market, and because their offerings are so fundamentally similar, the competition for this slice of the plane market is both intense and weirdly limited. If one company were to gain a clear technical advantage over the other, it would be a minor catastrophe for the losing company. And that’s what Boeing thought it was facing. The A320neo was trouble for Boeing Jet fuel is a major cost for airlines. With labor costs largely driven by collective bargaining agreements and regulations that require minimum ratios of flight attendants per passenger, fuel is the cost center airlines have the most capacity to do something about. Consequently, improving fuel efficiency has emerged as one of the major bases of competition between airline manufacturers. If you roll back to 2010, it began to look like Boeing had a real problem in this regard. Airbus was coming out with an updated version of the A320 family that it called the A320neo, with “neo” meaning “new engine option.” The new engines were going to be more fuel-efficient, with a larger diameter than previous A320 engines, that could nonetheless be mounted on what was basically the same airframe. This was a nontrivial engineering undertaking both in designing the new engines and in figuring out how to make them work with the old airframe, but even though it cost a bunch of money, it basically worked. And it raised the question of whether Boeing would respond. Initial word was that it wouldn’t. As CBS Moneywatch’s Brett Snyder wrote in December 2010, the basic problem was that you couldn’t slap the new generation of more efficient, larger-diameter engines onto the 737: Under the circumstances, Boeing’s best option was to just take the hit for a few years and accept that it was going to have to start selling 737s at a discount price while it designed a whole new airplane. That would, of course, be time-consuming and expensive, and during the interim, it would probably lose a bunch of narrow-body sales to Airbus. The original version of the 737 first flew in 1967, and a decades-old decision about how much height to leave between the wing and the runway left them boxed out of 21st-century engine technology — and there was simply nothing to be done about it. Unless there was. Boeing decided to put on the too-big engines anyway As late as February 2011, Boeing chair and CEO James McNerney was sticking to the plan to design a totally new aircraft. “We’re not done evaluating this whole situation yet,” he said on an analyst call, “but our current bias is to move to a newer airplane, an all-new airplane, at the end of the decade, beginning of the next decade. It’s our judgment that our customers will wait for us.” But in August 2011, Boeing announced that it had lined up orders for 496 re-engined Boeing 737 aircraft from five different airlines. It’s not entirely clear what happened, but, reading between the lines, it seems that in talking to its customers Boeing reached the conclusion that airlines would not wait for them. Some critical mass of carriers (American Airlines seems to have been particularly influential) was credible enough in its threat to switch to Airbus equipment that Boeing decided it needed to offer 737 buyers a Boeing solution sooner rather than later. Committing to putting a new engine that didn’t fit on the plane was the corporate version of the Fyre Festival’s “let’s just do it and be legends, man” moment, and it unsurprisingly wound up leading to a slew of engineering and regulatory problems. New engines on an old plane As the industry trade publication Leeham News and Analysis explained earlier in March, Boeing engineers had been working on the concept that became the 737 Max even back when the company’s plan was still not to build it. In a March 2011 interview with Aircraft Technology, Mike Bair, then the head of 737 product development, said that reengineering was possible. “There’s been fairly extensive engineering work on it,” he said. “We figured out a way to get a big enough engine under the wing.” The problem is that an airplane is a big, complicated network of interconnected parts. To get the engine under the 737 wing, engineers had to mount the engine nacelle higher and more forward on the plane. But moving the engine nacelle (and a related change to the nose of the plane) changed the aerodynamics of the plane, such that the plane did not handle properly at a high angle of attack. That, in turn, led to the creation of the Maneuvering Characteristics Augmentation System (MCAS). It fixed the angle-of-attack problem in most situations, but it created new problems in other situations when it made it difficult for pilots to directly control the plane without being overridden by the MCAS. On Wednesday, Boeing rolled out a software patch that it says corrects the problem, and it hopes to persuade the FAA to agree. But note that the underlying problem isn’t really software; it’s with the effort to use software to get around a whole host of other problems. Recall, after all, that the whole point of the 737 Max project was to be able to say that the new plane was the same as the old plane. From an engineering perspective, the preferred solution was to actually build a new plane. But for business reasons, Boeing didn’t want a “new plane” that would require a lengthy certification process and extensive (and expensive) new pilot training for its customers. The demand was for a plane that was simultaneously new and not new. But because the new engines wouldn’t fit under the old wings, the new plane wound up having different aerodynamic properties than the old plane. And because the aerodynamics were different, the flight control systems were also different. But treating the whole thing as a fundamentally different plane would have undermined the whole point. So the FAA and Boeing agreed to sort of fudge it. The new planes are pretty different As far as we can tell, the 737 Max is a perfectly airworthy plane in the sense that error-free piloting allows it to be operated safely. But pilots of planes that didn’t crash kept noticing the same basic pattern of behavior that is suspected to have been behind the two crashes, according to a Dallas Morning News review of voluntary aircraft incident reports to a NASA database: These pilots all safely disabled the MCAS and kept their planes in the air. But one of the pilots reported to the database that it was “unconscionable that a manufacturer, the FAA, and the airlines would have pilots flying an airplane without adequately training, or even providing available resources and sufficient documentation to understand the highly complex systems that differentiate this aircraft from prior models.” The training piece is important because a key selling feature of the 737 Max was the idea that since it wasn’t really a new plane, pilots didn’t really need to be retrained for the new equipment. As the New York Times reported, “For many new airplane models, pilots train for hours on giant, multimillion-dollar machines, on-the-ground versions of cockpits that mimic the flying experience and teach them new features” while the experienced 737 Max pilots were allowed light refresher courses that you could do on an iPad. That let Boeing get the planes into customers’ hands quickly and cheaply, but evidently at the cost of increasing the possibility of pilots not really knowing how to handle the planes, with dire consequences for everyone involved. The FAA put a lot of faith in Boeing In a blockbuster March 17 report for the Seattle Times, the newspaper’s aerospace reporter Dominic Gates details the extent to which the FAA delegated crucial evaluations of the 737’s safety to Boeing itself. The delegation, Gates explains, is in part a story of a years-long process during which 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.” But there are indications of failures that were specific to the 737 Max timeline. In particular, Gates reports that “as certification proceeded, managers prodded them to speed the process” and that “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.” Most of all, decisions about what could and could not be delegated were being made by managers concerned about the timeline, rather than by the agency’s technical experts. It’s not entirely clear at this point why the FAA was so determined to get the 737 cleared quickly (there will be more investigations), but if you recall the political circumstances of this period in Barack Obama’s presidency, you can quickly get a general sense of the issue. Boeing is not just a big company with a significant lobbying presence in Washington; it’s a major manufacturing company with a strong global export presence and a source of many good-paying union jobs. In short, it was exactly the kind of company the powers that be were eager to promote — with the Obama White House, for example, proudly going to bat for the Export-Import Bank as a key way to sustain America’s aerospace industry. A story about overweening regulators delaying an iconic American company’s product launch and costing good jobs compared to the European competition would have looked very bad. And the fact that the whole purpose of the plane was to be more fuel-efficient only made getting it off the ground a bigger priority. But the incentives really were reasonably aligned, and Boeing has only caused problems for itself by cutting corners. Boeing is now in a bad situation One emblem of the whole situation is that as the 737 Max engineering team piled kludge on top of kludge, they came up with a cockpit warning light that would alert the pilots if the plane’s two angle-of-attack sensors disagreed. But then, as Jon Ostrower reported for the Air Current, Boeing’s team decided to make the warning light an optional add-on, like how car companies will upcharge you for a moon roof. The light cost $80,000 extra per plane and neither Lion Air nor Ethiopian chose to buy it, perhaps figuring that Boeing would not sell a plane (nor would the FAA allow it to) that was not basically safe to fly. In the wake of the crashes, Boeing has decided to revisit this decision and make the light standard on all aircraft. Now, to be clear, Boeing has lost about $40 billion in stock market valuation since the crash, so it’s not like cheating out on the warning light turned out to have been a brilliant business decision or anything. This, fundamentally, is one reason the FAA has become comfortable working so closely with Boeing on safety regulations: The nature of the airline industry is such that there’s no real money to be made selling airplanes that have a poor safety track record. One could even imagine sketching out a utopian libertarian argument to the effect that there’s no real need for a government role in certifying new airplanes at all, precisely because there’s no reason to think it’s profitable to make unsafe ones. The real world, of course, is quite a bit different from that, and different individuals and institutions face particular pressures that can lead them to take actions that don’t collectively make sense. Looking back, Boeing probably wishes it had just stuck with the “build a new plane” plan and toughed out a few years of rough sales, rather than ending up in the current situation. Right now the company is, in effect, trying to patch things up piecemeal — a software update here, a new warning light there, etc. — in hopes of persuading global regulatory agencies to let its planes fly again. But even once that’s done, Boeing faces the task of convincing airlines to actually go buy its planes. An informative David Ljunggren article for Reuters reminds us that a somewhat comparable situation arose in 1965 when three then-new Boeing 727 jetliners crashed. There wasn’t really anything unsound about the 727 planes, but many pilots didn’t fully understand how to operate the new flaps — arguably a parallel to the MCAS situation with the 737 Max — which spurred some additional training and changes to the operation manual. Passengers avoided the planes for months, but eventually came back as there were no more crashes, and the 727 went on to fly safely for decades. Boeing hopes to have a similar happy ending to this saga, but so far it seems to be a long way from that point. And the immediate future likely involves more tough questions. A political scandal on slow burn The 737 Max was briefly a topic of political controversy in the United States as foreign regulators grounded the planes, but President Donald Trump — after speaking personally to Boeing’s CEO — declined to follow. Many members of Congress (from both parties) called on him to reconsider, which he rather quickly did, pushing the whole topic off Washington’s front burner. But Trump is generally friendly to Boeing (he even has a Boeing executive serving as acting defense secretary, despite an ongoing ethics inquiry into charges that he unfairly favors his former employer), and Republicans are generally averse to harsh regulatory crackdowns. The most important decisions in the mix appear to have been made back during the Obama administration, so it’s also difficult for Democrats to go after this issue. Meanwhile, Washington has been embroiled in wrangling over special counsel Robert Mueller’s investigation, and a new health care battlefield opened up as well. That said, on March 27, FAA officials faced the Senate Commerce Committee’s Subcommittee on Aviation and Space at a hearing called by subcommittee Chair Ted Cruz (R-TX). Cruz says he expects to call a second hearing featuring Boeing executives, as well as pilots and other industry players. Cruz was a leader on the anti-Boeing side of the Export-Import Bank fight years ago, so perhaps he’s more comfortable than others in Congress to take this on. When the political system does begin to engage on the issue, however, it’s unlikely to stop with just one congressional subcommittee. Billions of dollars are at stake for Boeing, the airlines that fly 737s, and the workers who build the planes. And since a central element of this story is the credibility of the FAA’s process — in the eyes of the American people and in the eyes of foreign regulatory agencies — it almost certainly isn’t going to get sorted out without more involvement from the actual decision-makers in the US government.
  23. boestar, I don't think the additional information is needed and is not, in the context of flying airliners, a suitable countermeasure. For airline pilots, particularly non-military-fighter types, AoA is a secondary piece of information. If AoA is to be implemented, then mental habits have to change to accomodate a new way of viewing the wing. One cannot make both airspeed and AoA equal in the pilot's mind due to the obvious potential for confusion. Airline pilots fly by speed not AoA, and introducing data on the PFD in an abnormal situation could be confusing in terms of a quick intellectual apprehension, (mental modelling), necessary for timely and correct decision-making. We are accustomed to "obeying" airspeed, not AoA and when the priority suddenly becomes "AoA over speed or pitch", even though perfectly correct, may in a rapidly unfolding situation which is becoming more confusing by the second, render AoA of dubious value. This is not to dismiss AoA itself as valuable; out of interest, I used to watch it using the ACMS section of the rear MCDU on the A330/A340 when in cruise. But the modelling of behaviours necessary to make it become "primary" in pilot awareness when we've used airspeed as primary forever, is a signifcant change which may not be necessary, for as I have mentioned before, recognizing and using AoA still doesn't have any "saves" to its credit in airline work. It may have such a potential, but planning for or requiring its use is by no means straightforward, as just displaying AoA on the PFD or even installing a comparator does not resolve the question of which parameter to prioritize when AoA's don't match by a set value and set off yet another attention-getting device to which the pilots must intutively react, possibly swiftly.
  24. Hi Vs... If I might add for boestar; with the B737MAX engine-arrangement, there is the thrust component (that causes a pitch-up force) that Vs mentions but actually the greatest contributor is the size of the nacelles which, as pitch angles increase, adds a lift component that, as the aircraft approaches the stall, alters the ordinary (B737 type-certified) stall characteristics such that the airplane's response is no longer linear but increasing. To retain the type-rating, something had to be installed to bring the curve down to match the stall characteristics of the other three iterations of the B737 type. Boeing wrote software that uses the STS, Speed Trim System that begins to counter pitch-up at thresholds set in the software. With millions of hours of event-free flight, it appeared as though the system was benign, until incorrect AoA data was fed into the MCAS. Boeing assumed pilots would respond as-trained to a "runaway" stabilizer system, the characteristics of which are, in the Boeing product, obvious with the large, continuously-rotating stabilizer trim wheel on the pedestal. The behaviour of the MCAS, as we now know, is different, giving little, short bursts of nose-down trim, which the B727/B737 does all the time. So the symptoms of trouble were masked by "normal behaviour" of the trim wheel until the airplane began to pitch down. Couple this with an unreliable airspeed on the left side and constant stall warning, and the crew is faced with a mammoth diagnostic problem and "no checklist or drill" that fits what they're seeing/experiencing and the control column just gets heavier. It is plainly obvious now because we all know more, and at least one pilot did on the Lion Air aircraft.