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MAX’s Return Delayed by FAA Reevaluation of 737 Safety Procedures

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MAX’s Return Delayed by FAA Reevaluation of 737 Safety Procedures

Old 21st Oct 2019, 10:00
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The Lion Air final report will be shared with the families of the victims on Wednesday. Public release date not announced yet.

Lion Air 737 MAX families set for crash report briefing
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Old 21st Oct 2019, 10:26
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Originally Posted by OldnGrounded
Edit: That simulator problem being blamed . . .
. . . is with the e-cab that the MAX chief was claiming could enable delivery of aircraft without test flights, if not for those annoying certification requirements.
Not just that, my understanding is that the e-cab is supposed to be exactly the same computers running the same software as the actual plane, so saying it was faulty "simulator software" doesn't make sense, to me at least. We don't know which software version it was, if it was the same as final production or indeed if it is a version that was ever flight tested - maybe Forkner made a defect report on it and it was modified before it flew. But that isn't what Boeing is saying, what they are saying makes no sense. Also worth noting that the e-cab isn't full motion (from the pics I have seen) so wouldn't have been able to replicate -ve g effects or anything like, and nor does it appear he had stick shaker or EFS to contend with, yet he still appears to have had a big problem with it.

There's another problem with Boeing statement though - they insist the FAA and other CAAs were informed of the changes to MCAS (directly contradicting the JATR report - not like B are going to need anything from those organisations any time soon...), and also that those changes were demonstrated in flight testing in Aug 2016. Forkners messages are from November 2016. So they were flight testing in August but the magic simulator which was supposed to mean they didn't need actual flight tests was "still undergoing testing and qualification and had not been finalized" in November. Huh?

Final irony, for those that haven't spotted it already, is of course that had Boeing really really captured the regulator and been allowed to certify "without test flights" they would never have discovered their modelling c**k-up, they would never have changed MCAS, and the MAX would probably have been safer... (and no that doesn't mean I think it should have been done that way).


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Old 21st Oct 2019, 10:59
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Originally Posted by infrequentflyer789
Not just that, my understanding is that the e-cab is supposed to be exactly the same computers running the same software as the actual plane, so saying it was faulty "simulator software" doesn't make sense, to me at least. We don't know which software version it was, if it was the same as final production or indeed if it is a version that was ever flight tested - maybe Forkner made a defect report on it and it was modified before it flew. But that isn't what Boeing is saying, what they are saying makes no sense. Also worth noting that the e-cab isn't full motion (from the pics I have seen) so wouldn't have been able to replicate -ve g effects or anything like, and nor does it appear he had stick shaker or EFS to contend with, yet he still appears to have had a big problem with it.

There's another problem with Boeing statement though - they insist the FAA and other CAAs were informed of the changes to MCAS (directly contradicting the JATR report - not like B are going to need anything from those organisations any time soon...), and also that those changes were demonstrated in flight testing in Aug 2016. Forkners messages are from November 2016. So they were flight testing in August but the magic simulator which was supposed to mean they didn't need actual flight tests was "still undergoing testing and qualification and had not been finalized" in November. Huh?

Final irony, for those that haven't spotted it already, is of course that had Boeing really really captured the regulator and been allowed to certify "without test flights" they would never have discovered their modelling c**k-up, they would never have changed MCAS, and the MAX would probably have been safer... (and no that doesn't mean I think it should have been done that way).
Wasn't the need to extend MCAS to the low speed 1G region only discovered fairly late in the flight test campaign? I am sure I've read that from a reliable(?) source, could be Leeham or SatcomGuru. If so, then an August demonstration might have only involved the high speed +1G wind up turn? I dont trust anything Boeing is saying now without some other verification.

First flight was on Jan 29 2016 and FAA certification was in March 2017.
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Old 21st Oct 2019, 11:02
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Originally Posted by infrequentflyer789
Not just that, my understanding is that the e-cab is supposed to be exactly the same computers running the same software as the actual plane, so saying it was faulty "simulator software" doesn't make sense, to me at least. We don't know which software version it was, if it was the same as final production or indeed if it is a version that was ever flight tested - maybe Forkner made a defect report on it and it was modified before it flew. But that isn't what Boeing is saying, what they are saying makes no sense. Also worth noting that the e-cab isn't full motion (from the pics I have seen) so wouldn't have been able to replicate -ve g effects or anything like, and nor does it appear he had stick shaker or EFS to contend with, yet he still appears to have had a big problem with it.

There's another problem with Boeing statement though - they insist the FAA and other CAAs were informed of the changes to MCAS (directly contradicting the JATR report - not like B are going to need anything from those organisations any time soon...), and also that those changes were demonstrated in flight testing in Aug 2016. Forkners messages are from November 2016. So they were flight testing in August but the magic simulator which was supposed to mean they didn't need actual flight tests was "still undergoing testing and qualification and had not been finalized" in November. Huh?

Final irony, for those that haven't spotted it already, is of course that had Boeing really really captured the regulator and been allowed to certify "without test flights" they would never have discovered their modelling c**k-up, they would never have changed MCAS, and the MAX would probably have been safer... (and no that doesn't mean I think it should have been done that way).
They are just splitting hairs I guess.
This "e-cab" sounds linke something which is generally refered to as a Hardware in the loop simulator.
All your cockpit and half the electronics bay is "real" (e.g. FCC and AP are, radios most likely not, IRS coud be not or half/half i.e. sensors are not, whereas computational unit is) , the sensors are not (sensor model), plane is not (plant model), environment is not (environment model).

Your AOA signal will then be generated based on aerodynamical calculations from the plant model (which interacts with the environment model), fed into the sensor model, which then generates either an analog signal - corresponding to what the vane would give you - or a digital signal - corresponding to what which ever box connects to the vane would give you. From there it runs into the real boxes.

From the tales told it seems a "real" MCAS event has happened due to some fault in either plant or sensor model. Therefore no one expected to see that in the wild. Well until a faulty single AOA vane produced the very same mess than some faulty model in the sim. So it doesn't matter if the the fault was intentionally inserted as part of a simulating a faulty AOA sensor or unintentionally due to some wrong coding in a sensor model - Mr F. got to know MCAS pretty much the same way than others would two years later.

So he did know now, that the envelope he described to the FAA for MCAS was, well, let's call it "incomplete" and that an MCAS event could be a pretty scary thing.
More intresting that this boozy conversation (well, other than regarding shop/sim floor morale during 737max development) is what happened the following days. Did he dig deeper? Did he report? To whom? Who pushed back? Would he have been allowed to follow up with FAA without asking for permission? Did he recieve a gag order?
So contrary to common perception I do not YET see him guilty. It all depends on the aftermath. Looking at the timeline will also be crucial (e.g. was the request to remove MCAS from the handbooks before or after that event?).

Anyway, on Wednesday Q3 figures are due by BA.

Last edited by BDAttitude; 21st Oct 2019 at 11:44.
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Old 21st Oct 2019, 11:41
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MCAS had concerns from the Tech Pilots - down to .2 M confirms that.

Speculation is above that speed it was still a concern - over the sms beer/s on a previous approach

If the culture at Boieng is to be believed now can this be treated - Did he dig deeper? Did he report? To whom? Who pushed back? Would he have been allowed to follow up with FAA without asking for permission? Did he recieve a gag order?

What exactly would YOU do and would your wife agree?
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Old 21st Oct 2019, 11:42
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I also will say, imagining about how to prep Forkner for dep or trial...I mean, what will look worse to court or jury? - Mr Forkner enmeshed in Boeing's "fast-and-cheap" MAX cadre, a cadre for which the company will pay and pay dearly in other courtrooms for other wrongs inflicted, or First Officer Forkner, hired knowing his past involvement, or, hired without finding out?
Its odd that someone who was allegedly so critical of MCAS (albeit possibly in its earlier - pre-certified - incarnation, as Boeing is stating) opted to join an airline which was replete with 737 MAX's. One would have thought he would have chosen an airline with an Airbus fleet or somesuch.
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Old 21st Oct 2019, 11:45
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Where would a 737 MAX pilot go to? To some big Boeing operator not to some Airbus operator.
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Old 21st Oct 2019, 11:56
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Originally Posted by Bend alot
What exactly would YOU do and would your wife agree?
My life and my career have taught me that in such circumstances it is best to pause, think for a moment, then do what you have to do and ask for forgiveness later. Otherwise as an engineer in a big coorp. you are no longer in control and could easily find yourself in a situation like Mr. F.
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Old 21st Oct 2019, 16:00
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Monday BA Financial News

From Reuters this (US) morning:

Boeing may face billions more in losses as MAX crisis deepens: analysts

Ankit Ajmera

(Reuters) - Boeing Co (BA.N) may have to book billions of dollars in additional charges related to its grounded 737 MAX jets, brokerages said on Monday, following reports that call into question the timing of the aircraft’s return to service.

Credit Suisse and UBS downgraded the stock after reports on Friday showed internal messages between two Boeing employees stating that the plane’s anti-stall system behaved erratically during testing before the aircraft entered service.

The new revelations pose fresh challenges for Boeing, which is reeling under pressure after two fatal crashes forced the company to ground the planes and book billions of dollars in losses.Boeing's shares fell as much as 5.7% to $324.40 in early trading on Monday, making the stock the biggest percentage loser on the Dow Jones Industrial Average. They have lost 18% of their value since the second deadly crash of the popular single-aisle jet in March.

The planemaker has already cut production of the MAX, and analysts said there was an increasing possibility that the company would have to halt production altogether.

“We see increasing risk that the Federal Aviation Administration won’t follow through with a certification flight in November and lift the emergency grounding order in December,” UBS analyst Myles Walton said, downgrading the stock to “neutral” from “buy”.

More
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Old 21st Oct 2019, 18:04
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Salute!

TNX for the update, Old...
I am more of a pilot and engineer than corporate type. So I wonder why Boeing doesn't bite the bullet and solve the basic aero problem and get rid of MCAS. Otherwise, get the variance from FAA and implement a hybrid FBW system to corrwct the aero problem.
Good grief, Airbus has been flying planes since the early 1990's with zero control stick feedback from AoA or atual aero forces on the elevator, aileron etc.. I really need an explanation of how they got their 320 and following planes certified.

Gums ponders....
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Old 21st Oct 2019, 18:16
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Boeing finally expresses "regrets". The regrets are not about the faulty system that killed 300 people, not about (reportedly) misleading the FAA, and not even about (reportedly) failing to disclose these messages to the FAA after the first crash which could have grounded the plane and saved the passengers and crew of the second accident plane. No, these "regrets" are about how these email messages were not released in a manner that allowed a "meaningful explanation" (ie, "spin".)

Maybe Boeing needs to swap the functions of their PR and Engineering departments, by pure chance they might find somebody competent at their job that way.
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Old 21st Oct 2019, 18:34
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Originally Posted by Water pilot
Boeing finally expresses "regrets". The regrets are not about the faulty system that killed 300 people
Yes, if only they had said something like

"We deeply regret what happened with these accidents"
Oh hang on, they did.
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Old 21st Oct 2019, 19:18
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Originally Posted by gums
Salute!
Really need an explanation of how they got their 320 and following planes certified.

Gums ponders....
depend on what the requirement exactly is. If the requirement is for the feel to be consistent across the envelope, a fbw joystick exactly meets that with no extra programming!
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Old 21st Oct 2019, 19:31
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Salute Snyg!

We really need to reopen the Tech Log for "technical" discussion, ya think?

Let the Mod's delete the political crapola and such, but if we wish to prevent future crashes we need to look at the technical issues and scientific issues and human factor issues, huh?

I fully understand the stick getting "light" as AoA approaches the edge of the envelope. I flew one such beast for a year or two, but it had a few "protections" ( as the Airbus folks say) If you insisted on pulling back harder despite buffet, burble and wing rock. Sheesh. That same beast also had a pitch doofer like the 737 that increased the required back stick forces by using a pneumatic bellows. It was strictly "q" and not AoA or mach. All my other hydraulic flight control jets had no feed back of any sort- springs for roll and that was about all.

Gums sends...
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Old 21st Oct 2019, 19:37
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Originally Posted by gums
Salute!

TNX for the update, Old...
I am more of a pilot and engineer than corporate type. So I wonder why Boeing doesn't bite the bullet and solve the basic aero problem and get rid of MCAS. Otherwise, get the variance from FAA and implement a hybrid FBW system to corrwct the aero problem.
Good grief, Airbus has been flying planes since the early 1990's with zero control stick feedback from AoA or atual aero forces on the elevator, aileron etc.. I really need an explanation of how they got their 320 and following planes certified.

Gums ponders....
That's easy - Airbus is entirely based on the same sort of software covering for aerodynamic quirks that MCAS was intended for, but since Airbus cut all the connections they were forced to use a far more expensive redundant system, allowing certification. Why this was not done in the 737 was to maintain commonality because that's what customers demanded. The reason Airbus did it was so they could provide similar feel to a wide range of planes that actually don't perform similarly which is what their customers wanted.

I expect there is no aero fix besides selling 787s into that slot which, again, the customers buying 737s did not want. I expect that fixed surfaces capable of producing and offsetting nose-down moment at high AoA will overcorrect everywhere else, producing a pronounced nose-down moment in level flight, requiring up-trim and excessive fuel burn.

There isn't a fundamental problem with MCAS; there is a fundamental problem with the AoA system that tells pilots and other systems incorrect information about the status of the airplane. Had the FCCs simply dropped out when the AoA became unreliable, it would have taken MCAS with them. There was no need to report a stall condition when there wasn't one and no need to correct for a high AoA when that was also untrue.
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Old 21st Oct 2019, 20:09
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Originally Posted by gums
Salute!
Good grief, Airbus has been flying planes since the early 1990's with zero control stick feedback from AoA or atual aero forces on the elevator, aileron etc.. I really need an explanation of how they got their 320 and following planes certified.
Gums ponders....
An earlier post by infrequentflyer789 addressed this question (my emphasis). Is anybody in a position to comment?

MAX’s Return Delayed by FAA Reevaluation of 737 Safety Procedures (My emphasis)

All (civilian) fbw a/c with neutral stability control laws (C*) are certified under special conditions starting with A320 (actually arguably with Concorde but that was such a different beast it must have been all special conditions), those SCs, or at least the rationale, have more or less carried over since then (all later buses and other makers too now). I think even today (30+ yrs after A320 and much longer after the birds you flew) fbw is still referred to as "novel or unusual design feature" in certification The rationale is that the control force cues for heading towards the edge of the envelope are not required if the edge of envelope is protected by hard limits / fences instead (similarly MCAS is not needed on autopilot because the autopilot is fenced/limited). Pretty sure this was well covered on the 447 threads, mind you so was everything...

Boeing took a different approach with 777/787, inventing C*U and providing a completely artificial feel on conventional controls, which I think allows them to meet the normal control force / stability reqs of part 25 without special conditions.

All these approaches fail in some way when stuff breaks and the a/c doesn't know (accurately) where it is in the envelope, AF477 ended up in a C* law without protection, C*U will inevitably reduce to C* if U is unknown (or deemed unreliable). There is a general principle (which turns into a requirement somewhere in the regs. I think) that any degradation of handling qualities must be inversely related to probability of occurrence and seriousness of failure consequences - that is the bit of the design and approvals process that MCAS seems to have got fatally wrong.
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Old 21st Oct 2019, 20:37
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Agree with gums; technical issues belong elsewhere.
The 737 Max problem is not associated with FBW or stick configuration.
The 737 Max aerodynamic issue involves a stability deficiency (not instability or complete flight envelope), which is corrected by use of background trim to adjust stick force (pilot’s perception of stability). The problem is with the implementation of the system and particularly its overall integrity wrt single sensor failure (or equivalent) which was exposed by the two accidents.

This thread opened at a time where it was envisaged that a simple software ‘fix’ (Boeing proposal 1) and new / revised checklists would provide an acceptable solution. Neither has done so, hence the wide-ranging discussion as more information becomes available, and the apparent difficulty in providing an acceptable solution for all authorities.
The situation is further complicated by the exposure of a deficient certification process, and the world wide views on piloting capabilities in rare abnormal failures.

As of now, Boeing has yet to provide an acceptable technical solution for recertification of MCAS. Then it is not clear how much work will be involved addressing concerns about recovery from extreme trim offsets which were identified as a consequence of the accidents. Checklist / training might be sufficient, but perhaps not acceptable to all ‘agencies’ involved.

The general deficiency of poor / multiple alerting and crew response, and any credit for human involvement for failure cases in support of certification might be outside of the agreed certification baseline for the Max (grandfather rights), thus this should not be a current problem.
However, nothing should be taken assured with this complex issue.

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Old 21st Oct 2019, 20:41
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Salute!

Thanks, Peter.....
Gotta review all the control law names, as I am more familiar with pitch gee/rate, roll rate and such.
Also have to reopen the Tech Logs for "technical" stuff.
One point before retiring back to the cave is:
There is a misconception about FBW control laws and actual aerodynamic characteristics of the plane. The ';bus seems to be very stable or we would not have had 447. In short, all the electrons did was replace a lotta cables, ropes and pulleys. In doing so, it was a no-brainer to implement gee, roll and other "protections". and more. My relic Viper did the same thing because the aerodynamics had neutral or negative static stabilty below 0.95 M. Big deal, but gave us super pitch rates and other things that our flight control laws kept us under control.

To this day I fail to undertand a requirement to provide stick/wheel/yoke feedback that we old farts endured in the 50's and before. OTOH, the Max apparently had a nasty tendency to exhibit a "light stick" when several degrees AoA below the stick shaker. A Max pilot could comment here, but they are scarce these days.

Gums sends....
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Old 21st Oct 2019, 21:17
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Originally Posted by Icarus2001
Just for the record. MCAS did not fail in these incidents (with available information so far).
The culprit was a SINGLE AoA vane that sent erroneous data to the MCAS. If the vane had a duplicate then MCAS would not be seen as the villain it currently is.

Imagine if a single vane activated a stick pusher at low altitude. Would you blame the stick push system or the design of a single vane having so much authority?
The reliability of AoA sensors is fairly well known in transport aviation, certainly by the world leaders in transport airplane manufacturing. I would blame the OEM manufacturer, who chose to rely on a single AoA at a time, and failed to determine and understand what the consequences of failure could be.
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Old 21st Oct 2019, 21:17
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re peter h
Boeing took a different approach with 777/787, inventing C*U and providing a completely artificial feel on conventional controls, which I think allows them to meet the normal control force / stability reqs of part 25 without special conditions.
Boeing 787 did include an Inertial nav system ' compare or monitor ' re SYNTHETIC airspeed and other factors independent of any external sensors
Introducing the 787 - Effect on Major Investigations - And Interesting Tidbits
Air Safety Investigation ISASI september 2011 by tom dodt Chief Engineer

About midway thru the document... Which can be downloaded as a pdf
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