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MAXís Return Delayed by FAA Reevaluation of 737 Safety Procedures

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MAXís Return Delayed by FAA Reevaluation of 737 Safety Procedures

Old 8th Jul 2019, 05:40
  #1201 (permalink)  
 
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Originally Posted by Maninthebar View Post
MCAS trims at a greater rate than electric (yoke switch) trim.

How many seconds of electric trim would be required to counterract 9.2 seconds of MCAS?

Are there any other circumstances under which you would expect to have to trim continuously for that length of time (or more if more than one MCAS activity had run undetected)?
The short answer is there is no earthly reason to let the trim run that long without doing something about it - that is why it is called Runaway Stab Trim. Keep in mind that the expected pilot reaction time to Runaway Trim was 3 seconds. Now even I think that’s a bit tight, but 9 seconds is three times as long. If the pilot doesn’t like where the trim is, or where the trim is going, the solution is literally right under his/her thumb.

Last edited by yoko1; 8th Jul 2019 at 05:54.
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Old 8th Jul 2019, 05:44
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Originally Posted by 568 View Post
. We don't seem to train crews how to deal with these situations and how best to "prioritize malfunctions" in simulator events anymore!
Thank you for making my point. There is and always has been a training deficiency issue wrapped up in everything we are learning about these accidents.
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Old 8th Jul 2019, 05:51
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Originally Posted by Lonewolf_50 View Post
yoko1, I have been an aircraft commander in a multi-crew aircraft who has taken controls when the other pilot was having difficulty controlling the aircraft - *
And so have I, but that is a very different situation when the Captain/Aircraft Commander deems it is necessary to intervene. In the JT601 event, we are talking about a situation when the Captain voluntarily and with intent hands off the controls to his First Officer. If someone wishes to argue that the Captain gave his First Officer a handful of out-of-trim aircraft, Iím just going to have to point out that this would have been another crew error - which works against the narrative that there were no significant crew errors that led to the loss of control. You canít have it both ways.
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Old 8th Jul 2019, 06:05
  #1204 (permalink)  
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Originally Posted by 568 View Post
What you have stated has merit (IMHO).Even at this stage of the MAX grounding, I truly believe that the "high level" decision makers are still drinking the cool aid.You only have to read or listen to the choreographed Muppet words from the PR (or lack thereof) department in the windy City to learn that they cannot fathom the gravity of the situation.
Emerging from Turbulence: Boeing and Stories of the American Workplace Today Emerging from Turbulence: Boeing and Stories of the American Workplace Today
Hardcover – Oct 15 2015
by Leon Grunberg (Author), Sarah Moore (Author)


Evening, Lonewolf_50
Originally Posted by Lonewolf_50 View Post
yoko1, . . .I'd be careful of making such a sweeping statement about what a pilot would or would not do on a forum with a lot of pilots. . .

Last edited by PJ2; 8th Jul 2019 at 06:18.
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Old 8th Jul 2019, 06:31
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Originally Posted by Maninthebar View Post
MCAS trims at a greater rate than electric (yoke switch) trim.

How many seconds of electric trim would be required to counterract 9.2 seconds of MCAS?
MCAS AND trim followed by electric trim ANU (from the ET302 report):



MCAS is faster, but not by much.
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Old 8th Jul 2019, 06:35
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Originally Posted by wonkazoo View Post
When your words convey an antagonistic and jingoistic view of the majority of crews who are intended to fly the damn thing in the first place it is reasonable to ask what purpose they serve. And lord help you if you are ever placed in a similar crucible. Here's hoping your peers will be more respectful of you than you were of them.

Regards,
dce
Dce,
what you are doing is all grist on his mill.
Whenever some detail comes under scruntity that could overshadow the official statements of BA, he will produce a lengthy post full of whataboutisms towards the crews and the industry in general stirring emotions from everyone who finds himself behind the controls of an aircraft professionally or leisurely or is somehow employed in the industry, thus derailing the discussion from a technical exchange aimed at increasing knowledge in the public domain to some emotional catfight. He would then try to keep this alive with pricking, This is his modus operandi... those attempts would be best ignored.

Yours respectfully
BD
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Old 8th Jul 2019, 06:40
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Since it was a brand new aircraft, and assuming that Boeing has a Jakarta based tech. rep , was he ever consulted after the aircraft landed from Den Pasar, and assisted in the trouble shooting ?
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Old 8th Jul 2019, 06:47
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Originally Posted by BedakSrewet View Post
Since it was a brand new aircraft, and assuming that Boeing has a Jakarta based tech. rep , was he ever consulted after the aircraft landed from Den Pasar, and assisted in the trouble shooting ?
Are you assuming or knowing that they have a resident engineer in Jakarta. Is this common practise? Would the resident be networked within the company or just a local hired guy with a business card and a phone?
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Old 8th Jul 2019, 07:11
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Originally Posted by DaveReidUK View Post
MCAS AND trim followed by electric trim ANU (from the ET302 report):



MCAS is faster, but not by much.
MCAS is a lot faster, actually 50 percent faster. It trims at 0.27 units/second versus main electric trim at 0.18 units/second with flaps up.

So, 9.2 seconds MCAS needs a whopping 13.8 seconds of main electric trim to fully counteract,
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Old 8th Jul 2019, 07:15
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Originally Posted by SteinarN View Post
MCAS is a lot faster, actually 50 percent faster. It trims at 0.27 units/second versus main electric trim at 0.18 units/second with flaps up.

So, 9.2 seconds MCAS needs a whopping 13.8 seconds of main electric trim to fully counteract,
Or even if detected after e.g. 6 seconds of operation (not bad in an environment with stick shaker, Master Caution Icing, and who knows whatnot) then 9 seconds in the other direction merely to get back to whatever trim desired before the onset of events.

I ask again, does anyone train for that?
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Old 8th Jul 2019, 07:18
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ICAO Annex 13 requires that State conducting investigation of an accident shall make the Final Report publicly available ďif possibleĒ within twelve months. Indonesia achieved this for QZ8501 and will strive to do so for JT610.

Annex 13 further requires that if the report cannot be made publicly available within twelve months, the State conducting the investigation shall make an interim statement publicly available on each anniversary of the occurrence Ė detailing progress and any safety issues identified.

Personally I donít see that Boeing/FAA Corp. can risk opprobrium of a return to service before Indonesian publishes at least a second interim report.

Boeing/FAA Corp. returned 787 to service before NTSBís damning critique of how hazardous batteries slipped thru certification - see NTSB Report 2014/AIR1401.

ďBoeingís electrical power system safety assessment did not consider the most severe effects of a cell internal short circuit ..., and the review of the assessment by Boeing authorized representatives and Federal Aviation Administration certification engineers did not reveal this deficiency.

Boeing failed to incorporate design requirements ....to mitigate the most severe effects of a cell internal short circuit, and the Federal Aviation Administration failed to uncover this design vulnerability ...

Unclear traceability among the individual special conditions, safety assessment assumptions and rationale, requirements, and proposed methods of compliance for the 787 main and auxiliary power unit battery likely contributed to the Federal Aviation Administrationís failure to identify the need for a thermal runaway certification test.Ē

Letís not do it again!
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Old 8th Jul 2019, 07:20
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Originally Posted by maxxer View Post
Sorry but i am an engineer and i am qualified to splice fiber optics, there is no fiber optics in the angle of attack sensors
I never said there was. However if you are an engineer and qualified to splice fibre optics then you'll know all about cleanliness requirements of connectors. So why make out the maintenance are doing something ridiculous just because it's a 'brand new' aircraft?
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Old 8th Jul 2019, 07:54
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Originally Posted by yoko1 View Post


The short answer is there is no earthly reason to let the trim run that long without doing something about it - that is why it is called Runaway Stab Trim. Keep in mind that the expected pilot reaction time to Runaway Trim was 3 seconds. Now even I think thatís a bit tight, but 9 seconds is three times as long. If the pilot doesnít like where the trim is, or where the trim is going, the solution is literally right under his/her thumb.
If MCAS will still have a maximum 9 second run time and a pilot should cut it in 3 seconds - what is the other 6 seconds of MCAS operation still required for?

The pilot will not like where it is going, as it is in an unfamiliar part of the flight envelope that it operates. So the pilot should cut MCAS when it is needed?
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Old 8th Jul 2019, 08:17
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Originally Posted by BedakSrewet View Post
Since it was a brand new aircraft, and assuming that Boeing has a Jakarta based tech. rep , was he ever consulted after the aircraft landed from Den Pasar, and assisted in the trouble shooting ?
I do not know about Boeing but another aircraft manufacture would have "aircraft support" included in the sales agreement.

For India on a small order of aircraft there was x hours of aircraft support given I think over one year and included a qualified engineer (mechanic) and/or technical records/maintenance control functions onsite. This equalled around one man for 5 months.

So I expect it is very variable - that said the MAX was sold as the same "almost" as a NG (pilots only need an hour on the iPad), so it is very possible the aircraft support was traded for a reduced sale price (more training reduction and another hole!).
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Old 8th Jul 2019, 08:29
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Considering the number of 737 series operated by Indonesian airlines like the Lion Air Group / Garuda, and Sriwijaya, ( again ) I assume that Boeing has a resident tech. rep to whom subject operators have access. Boeing should be in the position to answer that question....
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Old 8th Jul 2019, 08:41
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No assertion on this thread cannot get away from the simple fact that aircraft has been, and are still grounded globally. Fact. Airworthiness authorities concluded there is a fatal hazard with the "operating system" in totality of the 737MAX. Remedies to correct this fact may include aircraft modifications, crew training & documentation.

As SLF3 (post #1110) points out, the accident rate of the 737 Classic+NG (enormous sample size) is at least an order of magnitude lower than for the MAX. If we discount out runway excursions and CFIT accidents (almost always crew error) the difference would be even greater.

This is almost a perfect natural randomised controlled trial, identical crew training, identical safety systems, identical operators with a single variable, the type variant, I'm sure someone far smarter than me with a stat's background on this forum could calculate the probability of 2 MAX accidents being due to something other than the type variant. I suspect the number would be very small, only occurring a small number of times in the lifetime of the universe. Fact the 737 Classic+NG are still flying. Authorities are satisfied with the total operating system of these variants.

No doubt, a statistical analysis of the chances of these accidents being attributable to random crew error vs random aircraft error is so monumentally in favour of an aircraft malfunction, given the natural experiment that had been performed since 1967, the airworthiness authorities felt they had no choice but to had to act. They simply could could afford a third accident, without a monumental blow to public & pilot confidence, not just in the aircraft, but the entire system of aircraft certification.

There, no emotion, a little opinion, mainly just cold hard facts, the regulators act on facts.
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Old 8th Jul 2019, 10:54
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Originally Posted by BedakSrewet View Post
Considering the number of 737 series operated by Indonesian airlines like the Lion Air Group / Garuda, and Sriwijaya, ( again ) I assume that Boeing has a resident tech. rep to whom subject operators have access. Boeing should be in the position to answer that question....
https://www.boeing.com/global/boeing-southeast-asia/indonesia/index.page

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Old 8th Jul 2019, 11:26
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Originally Posted by Dan Winterland View Post
A full return to service date is pure speculation. I'm convinced the FAA (after due diligence) will return the Max to the skies and the US airlines will gladly launch them. But there are other elephants in the room. Arte other certification systems going to accept the FAA's recertification at face value? You can bet in the current climate that China won't. Ethiopia and Indonesia are going to be very sceptical as well. And what about the training? If pilots require practical training to convert to the Max, there aren't many Max simulators available right now. And you are going to have to convince the public the aircraft is safe. The IAG order was a big vote of confidence, but I'm sure we are going to see more order cancellations.
https://www.bbc.com/news/business-48899588
The IAG "order"was actually a letter of intent.
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Old 8th Jul 2019, 11:42
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Originally Posted by Lake1952 View Post
The IAG "order"was actually a letter of intent.

It presumably locked in a bargain basement price - which Airbus might wish to match.
It's was a 'no brainer' for WW. A win-win.
Only downside was 'public image' of buying a tainted product.
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Old 8th Jul 2019, 12:57
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Originally Posted by Bend alot View Post
If MCAS will still have a maximum 9 second run time and a pilot should cut it in 3 seconds - what is the other 6 seconds of MCAS operation still required for?

The pilot will not like where it is going, as it is in an unfamiliar part of the flight envelope that it operates. So the pilot should cut MCAS when it is needed?
Interesting take on the matter. So you're in quite a tight maneuvering spot and suddenly you get a "runaway trim" on top. Which, as the system was undisclosed, cannot look anything else than a genuine runaway trim to the pilots! Or perhaps the idea was that pilots are already used to STS, so trim going its merry way is now unsurprising... for how long?

It seems that in their zeal to leave no pilot error unturned, someone has uncovered another disturbing aspect of MCAS.

Now, for the real questions the above musings raise in a non-pilot (in case some of you have then answers on hand):
  1. This 3"-seconds-reaction-time-to-runaway figure comes from where? And is it further qualified with "in every possible situation", or "in straight and level flight", ...?
  2. How long are typical STS bursts?
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