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Boeing 737 Max Recertification Testing - Finally.

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Boeing 737 Max Recertification Testing - Finally.

Old 23rd Jun 2020, 08:53
  #101 (permalink)  
 
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Originally Posted by Bend alot View Post
I would say two MAX aircraft were un-serviceable (had issues that needed accurate warnings - it was NOT a runaway trim!)
QRH for B737 aircraft has long stated under the Runaway Stabilizer NNC as below:
Condition: Uncommanded stabilizer trim movement occurs continuously.
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Old 23rd Jun 2020, 12:50
  #102 (permalink)  
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So, what is the problem Ewbanks is talking about and what is his solution? Would it have avoided the Pakistani crash by better alerting the crew to their problem or is this a Boeing-only human factors solution?
The relevant design requirement applicable to the 737 says in part:

Sec. 25.1309 [Equipment, systems, and installations.]
.......
(c) Warning information must be provided to alert the crew to unsafe system operating conditions, and to enable them to take appropriate corrective action. Systems, controls, and associated monitoring and warning means must be designed to minimize crew errors which could create additional hazards.
'Sounds to me that the MCAS system malfunctioning as it did on the two crash airplanes constituted an unsafe system operating condition. The MCAS failing to operate as intended might be an unknown to the pilots? (I don't know, I'm not 737 rated). If the MCAS was malfunctioning, and the pilots did not know it did, or did not know what the correct action would be, would that design requirement have been met?

The 737MAX's delivered to American Airlines were equipped with an optional MCAS failure warning system? (which sounds like it would meet the design requirement). Other airlines received 737MAX's which were not equipped with this optional warning system? Would those airplanes meet the design requirement?
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Old 23rd Jun 2020, 12:52
  #103 (permalink)  
 
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Originally Posted by FlyingStone View Post
QRH for B737 aircraft has long stated under the Runaway Stabilizer NNC as below:
But in an MCAS nose down trim situation it doesn't. It can be stopped by main trim and then runs again when main trim is not active. So the condition statement is not completely correct and may explain why the crew who switched the trim system off in the first LionAir incident wrote it up as "speed trim working in reverse"
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Old 23rd Jun 2020, 13:36
  #104 (permalink)  
 
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But Pilot DAR, even if American's aircraft had the "MCAS warning system", was it not the case that the MCAS system overall and its functioning were covered only very briefly if at all in training, and likewise in the FCOM? Additionally, the intent of the regulation you have quoted - and it clearly is part of the context for the certification failures by both Boeing as well as FAA - is not to have the manufacturer skate, or to just get by, on a system with such significant effect on basic aeronautical stability.
Second, this set of warnings and systems was presented to airlines and the FAA within a template that very deliberately and very overtly said (in effect) "you know that 737NG version of the good ol' 737?...wellsir, there's hardly a dime's worth of difference between this brand-spankin' new MAX, and what you already know about all the wonderful safe operation maneuvering and handling characteristics of the airplanes you already have! So sign right here on the dotted line. . . ." It's one thing to make erroneous judgments - in this specific context about warning, relating to crew alerting and response times - to enable certification where it probably would not have been obtainable without those erroneous judgments. Isn't it a greater dereliction of responsibility to intensify the relevance of those erroneous judgments while telling airline customers, pilots and the FAA (and foreign regulators) alike that there are hardly any differences worth noting in the new variant?
(As SLF I am not emphasizing what I think could be another point: in an earlier thread there was a lot of discussion about whether the purpose of MCAS actually was largely or mostly to affect stick force gradients and also questions about basic aeronautical longitudinal stability and whether the airframe should have been tested, relative to that issue of stability, without MCAS. If that description of those other comments is accurate enough, then the warnings issue under the reg you cited, while relevant, I think is a secondary level point. The FARs do not contemplate an unsafe airframe which, with compliant warning systems, can be operated safely by fast-reacting pilots - until it is exposed as . . .. well, you know the rest.)
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Old 23rd Jun 2020, 19:45
  #105 (permalink)  
 
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Originally Posted by Pilot DAR View Post
'Sounds to me that the MCAS system malfunctioning as it did on the two crash airplanes constituted an unsafe system operating condition. The MCAS failing to operate as intended might be an unknown to the pilots? (I don't know, I'm not 737 rated). If the MCAS was malfunctioning, and the pilots did not know it did, or did not know what the correct action would be, would that design requirement have been met?

The 737MAX's delivered to American Airlines were equipped with an optional MCAS failure warning system? (which sounds like it would meet the design requirement). Other airlines received 737MAX's which were not equipped with this optional warning system? Would those airplanes meet the design requirement?
He claims the same flaw is also in the 777x. If it is specific why would he omit the exact solution he had identified that is in accordance with the latest human factors practice?
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Old 23rd Jun 2020, 19:59
  #106 (permalink)  
 
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Originally Posted by Pilot DAR View Post
The 737MAX's delivered to American Airlines were equipped with an optional MCAS failure warning system?
Is that not simply a reference to the previously-discussed (at length) "AOA DISAGREE" indication ?

If so, then hardly an "MCAS failure warning".
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Old 23rd Jun 2020, 20:09
  #107 (permalink)  
 
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The root cause is not human factors, unless you consider Boeing engineering screw ups to be human factors.

The root cause is Boeing Engineering gave MCAS lots of control authority and unlimited applications of this authority, and tied its activation to a electro-mechanical sensor with some pretty obvious and well known failure modes, yet never did any range checking in software to detect any of these well known failure modes, and never did any end to end testing to show these failure modes had benign outcomes because they do not. The fix was the one Boeing was close to releasing last April when the 2nd crash happened: fix all these glaring issues in MCAS. Let it have its one push to smooth the corner in the flight envelope, pass the certification test, move on.

The pilot community seems to be happy to fixate on "if I only had information X I would have sorted it out". Sure, but the better idea is to do as much as possible to make sure you don't need to rely on the pilot sorting it out. Fix the damn code so the plane won't keep pointing its nose at the ground repeatedly the minute the flaps go up. Sure, also, tell the pilots about the "feature" and how to deal with it, but start by not producing such a dangerous product.

I think Boeing is happy to keep the discussion focused on human factors because as the name says they are human factors and are thus subjective rather than objective. It's a lot better outcome from a liability point of view than focusing on how Boeing Engineering produced such a deeply flawed product.
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Old 23rd Jun 2020, 20:41
  #108 (permalink)  
 
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Originally Posted by FlyingStone View Post
QRH for B737 aircraft has long stated under the Runaway Stabilizer NNC as below:
But it got changed after the first crash, as it was incorrect to cover for a MCAS malfunction.
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Old 24th Jun 2020, 06:02
  #109 (permalink)  
 
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ElectroVlasic


as to ...

I still think Mr. Forkner involuntarily did exactly that and was very loquatious about it. Curious on how that plays out in the legal aftermath.
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Old 24th Jun 2020, 11:01
  #110 (permalink)  
 
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Legal after-calculus

The general rule is that (using terminology from U.S. civil litigation rules) when a "transaction or occurence" is something which becomes the subject of multiple civil lawsuits and those court actions are filed by various categories of parties (groups, individuals, companies) who claim they were harmed, then where there are potential criminal charges to be brought by prosecutors, the larger the number of civil lawsuits, the higher probability the charges will be evaluated as proper and will be initiated. Especially when the prosecutors are federal government authorities rather than at the state level. (I'm omitting any factor of election-year and/or Congressional or legislative political factors, beyond this parenthetical.)
But the sad and tragic saga of Boeing's excursion off of sound engineering and corporate accountability standards is so unprecedented, that any forecast is really just a seat-of-the-pants piece of guesswork.
The roster of lawsuits in Chicago continues to grow.....flight attendants also have filed claims in federal district court against the once-proud airframer.
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Old 25th Jun 2020, 13:29
  #111 (permalink)  
 
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September ?

Seattle Times reports (24 June) that Boeing may be restarting test flying as early as next Monday. Then providing the modified MCAS is accepted, the aircraft could return to service in Sept.

The initial inter-authority agreement would relate to MCAS, although Canada could include pulling SS cbs.

Full agreement on other system changes, consequences of AoA failure, is being debated, but likely to be a requirement for MAX -10, and retrofit to all variants by -10 certification date.

Possible areas being considered discussed here :- Boeing 737 Max Recertification Testing - Finally.

https://www-seattletimes-com.cdn.amp...ontrols/?amp=1
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Old 25th Jun 2020, 14:14
  #112 (permalink)  
 
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Flight Global report with regard to wiring inspections:
https://www.flightglobal.com/airfram...138982.article
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Old 28th Jun 2020, 08:38
  #113 (permalink)  
 
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Any news on the certification flight/s rumoured for this month?
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Old 28th Jun 2020, 08:47
  #114 (permalink)  
 
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Rumored to start tomorrow.
https://www.bloomberg.com/news/artic...?sref=ez43dC45
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Old 28th Jun 2020, 09:26
  #115 (permalink)  
 
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Reported also by Wall Street Journal (on website early June 28 with very reputable by-line):
https://www.wsj.com/articles/faa-to-...d=hp_lead_pos5
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Old 28th Jun 2020, 16:13
  #116 (permalink)  
 
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On the BBC as well.
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Old 28th Jun 2020, 23:15
  #117 (permalink)  
 
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FAA update (reportedly)

Reuters reporter, David Shepardson, posted on Twitter text from FAA email to Congress about next steps to return to service, including JOEB, FSB, TAB, CANIC....(Joint Operations Evaluation Bd., Flight Standardization Bd., ....)

davidshepardson (@davidshepardson) Tweeted: After @boeing 737 MAX certification flights here are remaining steps per @faa email to Congress today (Reuters reported no ungrounding expected before September) https://t.co/b7S9BF7y2O
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Old 29th Jun 2020, 15:41
  #118 (permalink)  
 
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Boeing has already flown the aircraft on multiple test flights for hundreds of hours. It would be interesting to hear a retrospective on those flights, many of which were deliberately wild rides. What issues, if any, were uncovered? Was there indeed s pitch up tendency that required something as ham handed as MCAS ?

Also, aside from Lion Air times two and the ET flight, have any verified reports of MCAS actively being engaged surfaced?
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Old 29th Jun 2020, 17:19
  #119 (permalink)  
 
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As at the grounding, there had been no recorded incidents of MCAS engagement in the NASA ASRS database.
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Old 29th Jun 2020, 17:30
  #120 (permalink)  
 
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Except for forensic data analysis, how could anyone report MCAS activation? There are no indications in the flight deck (pre-modification), no alerts of AoA disagree, etc.
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