800 MAX?

[jaylw314]

55 minutes ago, gsxrpilot said:

It's also been reported in the Seattle Times, that the combination of being in a full power climb, and because a single action of the MCAS results in 60 turns of the manual trim wheel, this can result in a condition where it is physically impossible to move the trim wheel by hand at that point. And that pilots have to go back to electric trim to free the wheel. But in this case, when trim is activated, the MCAS kicked back on a spun the wheel further. This error happening immediately on takeoff just left the pilots with not enough time or altitude to fix the issue.

As far as I can tell looking at the timeline, it looks like they turned the electric trim back on, made two trim up adjustments, and 5 seconds later the MCAS kicked in again.  It's not entirely clear to me in the report whether the trim telemetry would record manual movement of the trim wheel, but if it would, there doesn't seem to be any manual movement of the trim after they turned off the electric trim, at least until they turned it back on.  It's also not clear when they might have turned on the electric trim again

[BDPetersen]

Some 707/727/737 driver please refresh my memory. It seems that part of the manual trim drill included “unloading” the elevator to make it possible to turn the trim wheels. In other words, if a runaway trim, once disabled with the cutouts, left you with a substantial nose down trim condition, the required up elevator put such a load on the stabilizer that manual trim was very difficult even for two pilots. The procedure was to relax back pressure and then crank like crazy, sometimes requiring two or three such cycles until reestablishing in trim condition. 

Or am I misremembering. It’s been a few decades since I flew a small Boeing. I do recall that the standard simulator joke was in the event of a runaway trim to reach over and slam the copilot’s knee into the spinning trim wheel.

[flyboy0681]

 

 

[aviatoreb]

9 hours ago, flyboy0681 said:

 

 

That is just too cute.  I love that puppet pilot stops in the middle of talking as a jet flies over and he says, there goes a southwest seven three seven.  And the pilot mustache.  Just every way, this puppet guy nails it.

[BDPetersen]

Courtesy of Avweb

excessive airloads on the stabilizer could require the effort of both pilots to correct a mistrim condition. "In extreme cases, it may be necessary to aerodynamically relieve airloads to allow manual trimming. Accellerate or decelrate towards the in-trim speed while attempting to trim manually," the training guidance says.

[tigers2007]

Boeing is hitting the three week mark with the grounding. I wonder how much revenue has been lost. Seems like many airlines are always hanging by a thread financially (especially if they’re state sponsored). Were the Southwest and AA pilots just rescheduled into the mix?

 

OMG it never ends: https://www.google.com/amp/s/www.popularmechanics.com/military/aviation/amp27032708/air-force-stops-deliveries-of-trash-filled-kc-46-tankers-yet-again/

 

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[Andy95W]

3 hours ago, Hyett6420 said:

 

Have a read and then raise a toast to those pilots who tried so hard to save their own lives and thise of their passengers, but the aircraft had other ideas

Well said, Andrew.  Thanks.

[jaylw314]

On ‎4‎/‎6‎/‎2019 at 4:54 AM, BDPetersen said:

Courtesy of Avweb

excessive airloads on the stabilizer could require the effort of both pilots to correct a mistrim condition. "In extreme cases, it may be necessary to aerodynamically relieve airloads to allow manual trimming. Accellerate or decelrate towards the in-trim speed while attempting to trim manually," the training guidance says.

I saw elsewhere a former pilot suggesting high speeds can load the trim jackscrew enough to make it bind, and that in simulators they were taught to push the yoke forward to unload the trim mechanism to free it up.  I'd like to know if:

• this is part of the standard procedure for malfunctioning/runaway electric trim
• this is part of the standardized training for US and international pilots

The guy makes it sound like it's not part of standardized training, but it's a "trick" taught by sim instructors, but it'd be nice to know if anyone can verify this either way

https://youtu.be/HBqDcUqJ5_Q?t=996

 

[BDPetersen]

Not sure if you are saying that I implied it was a “trick”. It certainly was not. Just a slightly fuzzy memory of how we did things on the B707 and 727 ( which I flew). Having had time to fully assimilate that memory with the help of the Avweb article, I can assure you that was the manual trim procedure we were trained to do. ( The copilot knee part was a joke.)

[jetdriven]

12 hours ago, Hyett6420 said:

•  The pilots DID activate the trim cut out switches and they STAYED cutout, they were not reactivated as several people have said, here and elswhere.
• They tried to use the manual trim, it did not work.

http://www.ecaa.gov.et/documents/20435/0/Preliminary+Report+B737-800MAX+,(ET-AVJ).pdf

Andrew

The MCAS commanded a nose down input, however, the stab trim cutout switches prevented stab movement. Then the CA asked the FO if the trim was functional, then a stab trim momentary nose up input, then a large MCAS nose down input, basically to the forward stop.  Sounds like the cutout switches were turned on.

The trim whee has a foldout handle, to manually trim, they did not use this. The stab didnt move from the cutout position till the very end.

[flyboy0681]

On 4/6/2019 at 8:24 AM, tigers2007 said:

6 minutes ago, jetdriven said:

The MCAS commanded a nose down input, however, the stab trim cutout switches prevented stab movement. Then the CA asked the FO if the trim was functional, then a stab trim momentary nose up input, then a large MCAS nose down input, basically to the forward stop.  Sounds like the cutout switches were turned on.

The trim whee has a foldout handle, to manually trim, they did not use this. The stab didnt move from the cutout position till the very end.

 

I've been writing software for nearly 40 years now and every once in a while after my work has been placed into production I get a nagging feeling about a change that I've made and whether I accounted for everything. A few times it's come back to byte me in the ass, but I'm wondering if any of the people who wrote the MCAS software had the same feelings somewhere along the way. If they didn't I bet they do now.

 

[tigers2007]

This had nothing to do with it being a non european / american crew (that in my mind is frankly racist)  

Sir,

“european / american” are not a race. Please do not imply that racism is afoot on Mooneyspace. Even if it is in your own mind. If you feel that a member is out of line, please contact an Administrator to review their comment. We all get it that the pilots did everything they could and do appreciate your input.

Sincerely,

Tigers2007
A male non-Caucasian




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[jetdriven]

11 hours ago, Hyett6420 said:

so DESPITE you reading the report which clearly states that the cockpit data recorder shows that the trim switches remained in the cutout position you still maintain that they were turned back on again.  For reference you might also note that by pulling or pushing on the yokes the trim system was supposed to cutout regardless of whether the switches are on or off and THAT didn't happen either.  

 The report kind of glosses over that last little bit at the end. But it does not say the stab trim switches remain in cutout until impact.But it’s a government agency and a state owned airline so that happens sometimes. But here’s the deal, stab trim was cutout and MCAS commanded nose down, but the stab did not move. Later, just before the crash actually, short manual trim nose up input was applied and the stabilizer moved up....and then MCAS commanded a large nose down command then the stab moved almost to the forward stop. Like this article that I’m about to post shows, either somehow power got to those stab trim motors,  or they turned the switches back on . 

 

From the article http://visualapproach.io/et302-even-without-answers-the-data-tells-a-story/

“

Finally, in what seems like the final nail in the coffin for the doomed 737 Max, the automatic nose down trim activates once more for five seconds.  It is from this trim and speed combination that the aircraft becomes uncontrollable and pitches to a terrifying 40 degrees nose down attitude. 

Why did the MCAS reactivate?  We know the STAB TRIM CUTOFF switches had been moved to CUTOFF.  There are only two logical answers:  either the aircraft somehow overrode the cutoff switches… or the pilots manually reactivated the stab trim.  There is evidence for the latter as short bursts of nose up trim were recorded, followed by the five second delay, and the final reactivation of the MCAS. “ 

 

 

 

your turn. 

[jetdriven]

20 minutes ago, Hyett6420 said:

My turn is simple, read the report again.  It is the OFFICIAL REPORT, with EASA, NTSB, and a ton of other agencies involved in writing it.  Where in that report does it say the cut out switch was reset to ON?  It doesnt, not only that but it repeats taht the cutout switch was set to off.  It also states (as ive said before) that control wheel inputs will stop the electric trim and ap to disconnect regardless of swtch position.  This did not happen.  

I only interested in facts from official reports not an armchair analyst writing a blog.  

It is a preliminary report and does not have all of the data. But let me ask you this how do you explain the fact that the stabilizer moved electrically, just before the crash sequence. first in a manually commanded ANU direction, then an MCAS commanded AND direction.   The "armchair analyst" has good data, and it tells us something.  The MCAS tried to command a stabilizer input, yet the stab didnt move. Then, later, the stab moves,  manually commanded, and then automatically commanded. 

They turned the stab trim cutout switches back on.

from the report:

At 05:40:41, approximately five seconds after the end of the ANU stabilizer motion, a third instance of AND automatic trim command occurred without any corresponding motion of the stabilizer, which is consistent with the stabilizer trim cutout switches were in the ‘’cutout’’ position

At 05:43:11, about 32 seconds before the end of the recording, at approximately13,4002ft, two momentary manual electric trim inputs are recorded in the ANU direction. The stabilizer moved in the ANU direction from 2.1 units to 2.3 units.At 05:43:20, approximately five seconds after the last manual electric trim input, an AND automatic trim command occurred and the stabilizer moved in the AND direction from 2.3 to 1.0 unit in approximately 5 seconds.The aircraft began pitching nose down. Additional simultaneous aft column force was applied, but the nose down pitch continues, eventually reaching 40° nose down. The stabilizer position varied between 1.1 and 0.8unitsfor the remainder of the recording.

Edited April 9, 2019 by jetdriven

[jaylw314]

20 hours ago, BDPetersen said:

Not sure if you are saying that I implied it was a “trick”. It certainly was not. Just a slightly fuzzy memory of how we did things on the B707 and 727 ( which I flew). Having had time to fully assimilate that memory with the help of the Avweb article, I can assure you that was the manual trim procedure we were trained to do. ( The copilot knee part was a joke.)

I was referring to the guy in the video, not you.  unless you're the guy in the video! 

I was mainly asking if this was a standard part of the runaway/malfunctioning electric trim procedure and training if we have any 737 pilots out here...

[jaylw314]

20 hours ago, jetdriven said:

The MCAS commanded a nose down input, however, the stab trim cutout switches prevented stab movement. Then the CA asked the FO if the trim was functional, then a stab trim momentary nose up input, then a large MCAS nose down input, basically to the forward stop.  Sounds like the cutout switches were turned on.

The trim whee has a foldout handle, to manually trim, they did not use this. The stab didnt move from the cutout position till the very end.

Do we actually know they did not try to use the manual trim or the foldout handle?  As far as I could tell, the telemetry only shows there was no movement after turning off the cutout switch, but there's nothing in the telemetry or CVR that shows what they were doing (or trying to do) with the manual trim mechanism, right?

[Cyril Gibb]

On 4/9/2019 at 4:32 AM, Hyett6420 said:

 

The ideology underlying racism often includes the idea that humans can be subdivided into distinct groups that are different due to their social behaviour 

An interesting perspective although I disagree.  So people who don't act as I do are of a different race?  If I'm critical of someones politics, I'm being racist?

It's far too easy these days to accuse someone of being racist for far too trivial a reason.  From my narrower definition of racism I think the "third world" comment was really about training, expertise and experience, not a racist comment.  Broadening the term racist that much just increases the polarisation and tribalism that we see these days.

eg. Just because you guys beheaded MY Queen, I don't think it was racist, just politics.

[Guitarmaster]

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[Andy95W]

22 hours ago, Guitarmaster said:

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I'm ashamed to admit I found this humorous...

[DXB]

It seems like all  initial actions of the Ethiopian pilots were correct.  They were troubleshooting a problem that they recognized from the outset.  It seems their major error was never reducing throttle  when in a dive and at too high an airspeed to work the trim manually.  It might have ended better had they done so and unloaded the elevator rather rather than turn the stab trim back on in desperation.  But do 737 pilots train for this rather odd scenario? If not, it's hard to point the finger at them for not instinctively taking the best action when things really hit the fan. The fact that both of these crashes happened outside the developed world seems like a total red herring.  By contrast, there are so many fingers to point at Boeing and the FAA:

Not telling pilots about MCAS, reliance of MCAS on a single AOA sensor,  making it impossible to kill MCAS independent of killing electric trim, making a warning system for disagreement between the two AOA vanes an 80k option on a >100 million$ aircraft, and of course the inelegant tacked-on design of MCAS used to avoid need to certify and train folks on a whole new aircraft

It's very worst kind of interaction between a large corporate entity and a large government that led to these disasters and squandered our global leadership role in aviation.  It's particularly sad to see this happen to Boeing, a company whose design philosophy has traditionally tried to limit overuse of automation.  

 

[m20kmooney]

1 hour ago, DXB said:

But do 737 pilots train for this rather odd scenario?

Yes. Here in the US at least. 

“We have been trained on how to handle the mishap that occurred in at least the Lion Air jet that we know about. The manual described how a 737 Max will respond in the kind of scenario that would trigger MCAS, even if it did not name the software outright. Further, he says the FAA issued a directive after the Lion Air crash that provided clearer instructions. U.S. airlines have flown the 737 Max for more than 100,000 hours, including some 23,000 hours at United, without a problem. I can't really comment as to the training that they get overseas, but I know here in America ... we have not seen one data point saying that we had a performance or a maintenance issue with it.” James Belton. United Airlines pilot and spokesman for the Air Line Pilots Association.

[DXB]

5 hours ago, m20kmooney said:

Yes. Here in the US at least. 

“We have been trained on how to handle the mishap that occurred in at least the Lion Air jet that we know about. The manual described how a 737 Max will respond in the kind of scenario that would trigger MCAS, even if it did not name the software outright. Further, he says the FAA issued a directive after the Lion Air crash that provided clearer instructions. U.S. airlines have flown the 737 Max for more than 100,000 hours, including some 23,000 hours at United, without a problem. I can't really comment as to the training that they get overseas, but I know here in America ... we have not seen one data point saying that we had a performance or a maintenance issue with it.” James Belton. United Airlines pilot and spokesman for the Air Line Pilots Association.

My full query above, from which you quoted only the last sentence, was " It seems their major error was never reducing throttle  when in a dive and at too high an airspeed to work the trim manually.  It might have ended better had they done so and unloaded the elevator rather rather than turn the stab trim back on in desperation.  But do 737 pilots train for this rather odd scenario? "   

The quote you provide only cites the guidance in the 737 MAX Boeing manual for runaway trim and the FAA supplement to that flight manual issued after the Lion Air crash. I have posted both items below. Neither document says anything about how to mobilize an unmovable manual trim wheel after turning off the stab trim.   My question is whether 737 pilots are  trained on how to handle a manual trim wheel that cannot be moved after they turn off electric stab trim. If absence of such guidance, the Ethiopian pilots' disastrous decision to turn stab trim back on may have seemed like a perfectly reasonable move in a crisis.