ET crash ADD NBO

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Re: ET crash ADD NBO

#401 Post by barkingmad » Tue Apr 09, 2019 10:35 am

2 questions.

Why no feedback from the Lionair incident where the crew recovered thanks to jumpseater?

ET610 reportedly issuing smoke before impact. NG trim system says 2mins ON then 13mins OFF, presumably to let high current motor to cool off. But nothing on this so far?

Just a coupla thoughts.......

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Re: ET crash ADD NBO

#402 Post by ian16th » Tue Apr 09, 2019 10:56 am

Wine improves with age
I improve with wine :YMPARTY:

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Re: ET crash ADD NBO

#403 Post by ian16th » Thu Apr 11, 2019 11:11 am

Wine improves with age
I improve with wine :YMPARTY:

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Re: ET crash ADD NBO

#404 Post by Fox3WheresMyBanana » Thu Apr 11, 2019 11:26 am

...suggests the crew did not follow all the steps for the correct procedure for a runaway stabilizer.
Why would they? The MCAS operation with a missing AoA probe does not match the symptoms for a runaway stabilizer.

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Re: ET crash ADD NBO

#405 Post by Boac » Thu Apr 11, 2019 12:49 pm

I fully agree. The big mistake (in my opinion) by the crew in very difficult circumstances was not to reduce power and speed, which coupled with an unexplained failure to maintain pitch control using the electric trim led them to the crash.

A very confusing situation to be in, with, presumably, priority given to the stall warning and unreliable airspeed drills, with subsequent failure to recognise the MCAS nose-down trim inputs until too late. That's 3 emergency drills running at once. :((

It would, however, appear that the cause of the 'wrong' AoA signal may have been established - thought to be loss of the external part of the left AoA probe.

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Re: ET crash ADD NBO

#406 Post by barkingmad » Thu Apr 11, 2019 1:49 pm

For some odd reason the UAS drills by Boeing never include a visual check of the stab trim wheel position using the TLAR principle.

After AF447 whilst I still warmed the NG left-hand seat I mentally stored my rough parameters, when all hell breaks loose, especially at cruise altitude as 3-6-90. This is a quick reference as part of UAS item # 1 and costs nothing.

Easy numbers of 3 NU attitude, about 6 on the stab trim wheel and 90ish on the N1s.

Then start to work through the rest of the drills as prescribed.

So why has Mr B left out this important secondary flight control from this drill?

Can’t speak for the ‘Bus as I actively avoided a relationship during my career.

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Re: ET crash ADD NBO

#407 Post by Fox3WheresMyBanana » Thu Apr 11, 2019 1:56 pm

I would presume Boeing missed them out because remembering those numbers for one's aircraft is just basic airmanship. And the lack thereof displayed by the AF pilots is why I won't fly with AF any more.
Perhaps all pilots should spend some time flying Tiger Moths and the like, with no or minimal instruments, so they better understand when the instruments are useful, and how much can be done without most of them working.

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Re: ET crash ADD NBO

#408 Post by barkingmad » Thu Apr 11, 2019 2:22 pm

Fox, Granted the UAS figures, but my main point was the absence of a stab trim position check.

Just threw in the easy 3-6-9 numbers for those still unfortunate enough to be still NG enslaved.

Mind you the ability of the Magenta Children to remember and process numbers might rule that out.........?

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Re: ET crash ADD NBO

#409 Post by Fox3WheresMyBanana » Thu Apr 11, 2019 4:58 pm

I see your point. Always tricky what to include in the cards or leave out. I remember having long discussions with our resident A1 QFI on the F3, as he had had an input into writing them. He was the sim standards officer (as well as STANEVAL for the jet), and I his deputy. I also helped investigate a Cat3, near Cat5, accident where the nav had got lost in the cards due to there being so many of them, and each so long.
I am inclined still to go with leaving this out of the Boeing drills and improving general airmanship.
I would also repeat my argument for a single 'Give me the d@mn airplane' button which cuts out every-not-absolutely-essential system, then allow the crew to re-engage stuff from there, rather than the current approach which is to hope they will spot all the failures which have dropped the system performance below optimum. It's not just the limitations on the human brain which has me arguing for this, but also the sheer complexity meaning that combination or unexpected failure modes mean that the provided guidance is likely to be insufficient or even wrong, as with the MCAS.

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Re: ET crash ADD NBO

#410 Post by Boac » Thu Apr 11, 2019 7:01 pm

Fox3 wrote:I would also repeat my argument for a single 'Give me the d@mn airplane' button
- what you have not built into the plan is that hairy old pilots like me might press that button at start-up. =))

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Re: ET crash ADD NBO

#411 Post by Fox3WheresMyBanana » Thu Apr 11, 2019 9:46 pm

Mais bien sur, mon brave!
C'est exactement le point.

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Re: ET crash ADD NBO

#412 Post by ian16th » Fri Apr 12, 2019 10:21 am

Wine improves with age
I improve with wine :YMPARTY:

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Re: ET crash ADD NBO

#413 Post by Fox3WheresMyBanana » Fri Apr 12, 2019 10:52 am

However, the system is only needed to enhance stability with slats and flaps retracted at very light weights and full aft center of gravity ...
So, they are putting in a switch, and telling the pilots to only turn on MCAS when very light and with full aft CG? Or taking weight /CG data from elsewhere and using that?

This will fix the problem, but it does beg the question as to why MCAS wasn't built this way in the first place, and therefore makes it a pretty much open-and-shut case for all the lawsuits Boeing is currently facing. This will cost them billions. The question is, will it cost them enough that they start designing aircraft properly in future? Sadly, I doubt it.

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Re: ET crash ADD NBO

#414 Post by Boac » Fri Apr 12, 2019 11:20 am

No, being Boeing, they will probably use another piece of software taking weight and c of g from other sensors to switch MCAS on and off - what could possibly go wrong? :ymdevil:

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Re: ET crash ADD NBO

#415 Post by barkingmad » Fri Apr 12, 2019 11:43 am

Once upon a time when RAF was looking at the Tornado its acronym of MRCA was interpreted by lowly aircrew as "Must Refurbish Canberras Again".

What a shame Mr Boeing didn't quit at the NG800 stage and instead acquire all the old 75s and properly refurbish them. Another aircraft which had the reputation of "doing what it says on the tin"?

Instead they've pressed on with 739, not highly spoken of and on into the current 73 disaster zone.

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Re: ET crash ADD NBO

#416 Post by OFSO » Fri Apr 12, 2019 12:14 pm

Right. Just add more software taking i/p from existing sensors, add a switch, demonstrate it in the sim., and instruct via i-pads. No need to go near a real aircraft.

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Re: ET crash ADD NBO

#417 Post by Fox3WheresMyBanana » Fri Apr 12, 2019 12:30 pm

I repeat my point from much earlier. If they've screwed up this badly on MCAS, what else have they done wrong?

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Re: ET crash ADD NBO

#418 Post by barkingmad » Sat Apr 13, 2019 7:12 pm

Fox3WheresMyBanana wrote:
Fri Apr 12, 2019 12:30 pm
I repeat my point from much earlier. If they've screwed up this badly on MCAS, what else have they done wrong?
Answer: Try to stretch what was a great aircraft to somewhere beyond credulity and commonsense?

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Re: ET crash ADD NBO

#419 Post by Boac » Mon Apr 15, 2019 6:50 pm

The software 'fix' proposed by Boeing looks ok to me at a first glance. With full acknowledgement to Chris Brady from his excellent site http://www.b737.org.uk/mcas.htm#fix

"On 13 March 2019, the FAA issued an Emergency Order of Prohibition, prohibiting the operation of any MAX in the US.

https://www.faa.gov/news/updates/media/ ... _Order.pdf

The Proposed Fix

Boeing have been working on a software modification to MCAS since the Lion Air accident. Unfortunately although originally due for release in January it was not released due to both engineering challenges and differences of opinion among some federal and company safety experts over how extensive the changes should be.

Note that as MCAS is an FCC function, the modifications to MCAS are made in the FCC software. The revision will be known as FCC P12.1

There are three significant changes to MCAS software being worked on by Boeing:

To give the system input from both angle-of-attack sensors, Currently MCAS only uses data from the angle of attack sensor on the side of the active FCC, (see AoA source). The system will have split vane monitor and Mid Value Select (MVS) input. This will both enhance detection of erroneous AoA vane behaviour and the MVS signal selection will pick the average of ADIRU L & R and the previous MVS output. If the output of the two AoA vanes differ by more than 5.5 degrees MCAS will be disabled.
To limit how much MCAS can move the horizontal stab to guarantee sufficient handling capability using elevator alone. In its original report, Boeing said that MCAS could move the horizontal stabilizer a maximum of 0.6 degrees. However, after the Lion Air crash, it told airlines that MCAS could actually move it 2.5 degrees, or half the physical maximum. Boeing reportedly increased the limit because flight tests showed that a more powerful movement was needed at high AoA rather than at high Mach.
A modification to the activation and resynchronisation schedule. MCAS will be limited to operate only for one cycle per high AoA event, rather than multiple. At present it will operate for 10s, pause for 5s and repeat for as often as it senses the high AoA condition is present. Furthermore the logic for MCAS to command a nose up stab trim to return to trim following pilot eletric trim intervention or exceeding the forward column cutout switch, will also now be improved.

Furthermore there is expected be:

Changes to the on board displays. This includes making the AoA Disagree Alert standard on all aircraft and offering a free option to have the AoA display on the PFD;
FCOM explanation of MCAS and an updated Speed Trim Fail Non-Normal Checklist and revised QRH.
Type conversion training to cover speed trim and MCAS, existing crew procedures and related software changes.
Enhancements to the maintenance documentation, including specifically to the Airplane Maintenance Manual (AMM) and Interactive Fault Isolation Manual (iFIM)

By 11 Apr 2019, Boeing CEO, Dennis Muilenburg said that the MAX has made 96 flights totalling over 159 flight hours, to test the MCAS/FCC software update and that the flight test program was not yet complete. He said that "The software update functioned as designed" and that Boeing is working to address a glitch when separate software is integrated into the system that was uncovered during an internal review."


It basically puts MCAS how it should have been designed by Boeing! Now, why it happened the way it did................?

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Re: ET crash ADD NBO

#420 Post by Slasher » Mon Apr 15, 2019 11:16 pm

http://www.youtube.com/watch?v=24m-V2f9-sY

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