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Thread: OT: not about 737MAX, but yeah, it kinda IS about that.

  1. #21
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    Quote Originally Posted by enginuity View Post
    Heavy automation and lack of training is a disaster waiting to happen. And it happened. Twice.

    That and it is obvious that Boeing changed the flight envelope on the 737. To save certification costs and training costs they added some systems so it would fly like a regular 737. The 737 Max is not a 737, it is a new airplane and should have required all the checks and balances that go along with a new airplane.
    That is an FAA issue. Obviously the MAX was accepted to be similar enough not to need extra. And most of it is.... Word is that it is very similar to a prior model (I'd have to look that # up).

    I've been down that road with UL and FCC approvals.... it's a matter of staying just inside the rules, and it is all legal.
    1601

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  2. #22
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    Quote Originally Posted by RB211 View Post
    Last airline, I flew a CL65, better known as a CRJ. It had two disconnects for the yoke pitch and roll incase they became jammed. In the Sim, they would jam both, require us to pull the handles, now one pilot would have pitch control, the other one had roll, and we had to bring it back and land it, was always fun.
    We also practiced runaway stab trims and disconnecting the trim, being forced to fly it back with a ton of yoke pressure required beyond the airspeed the stab trim ended being set to.
    This might seem perverse to some, but without the pressure to succeed or pass the test, I might enjoy the challenge of that sim situation that requred 2 pilots active on the yokes. Somewhat like the desire to fly the shuttle sim before it was decomissioned (and being envious of friends that were able to do it)
    Thanks for sharing that bit of experience.
    Bill Pendergrass
    Rotec RM-1 w/Rusnok head
    Atlas TH42 QC10

  3. #23
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    I've continued to follow the discussion on airliners.net, of the doomed ET302 flight, and in post number 4104 there is a good synopsis of the events that led to the crash shortly after take-off:

    http://www.airliners.net/forum/viewt...519&start=4100

    Those of us who are involved in engineering and manufacturing might do well to consider the ramifications of errors in design or implementation, and especially management decisions that sometimes overrule objections of engineering in order to meet delivery deadlines or deal with competition to improve profits. It seems obvious that MCAS was poorly thought out and implemented in a rush, while also largely hidden and insufficiently tested and understood by pilots.

    I have certainly made my share of mistakes as a design engineer, but fortunately they have been minor and have not caused any injury to people, although they could have. But certainly not to the extent that could happen with aircraft. The most serious error I can recall making was with the design of a new circuit breaker test set that used relays to switch taps on 480 VAC 400 amp mains. We were performing initial testing of the prototype, and all was going well on the first tap. I remember saying, "Now I'll try tap 2", and I clicked the key on the computer keyboard to set it. As soon as I did, there was a flash and a loud BANG and the computer monitor went crazy and sparks and smoke were coming out, until some brave person ran to the main switch and cut power. The problem was that I had mislabeled the pin numbers on one of the relays, which cross-connected the 480 VAC supply and the control coil that shared a common ground with the 5 VDC logic as well as that of the computer. Upon autopsy, it was obvious (to me) that the #10 AWG power wire went to a small screw on the relay, and the #22 AWG control wire went to a much larger power lug. But the technicians who wired it did not notice the discrepancy or did not report it. After that, we built a lower capacity power supply for testing purposes, and only connected to the high current line when the unit had been fully tested at low power.

  4. #24
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    Quote Originally Posted by PStechPaul View Post
    especially management decisions that sometimes overrule objections of engineering in order to meet delivery deadlines or deal with competition to improve profits.
    Unfortunately too often true. Another recent example is VW Deiselgate.
    Bill Pendergrass
    Rotec RM-1 w/Rusnok head
    Atlas TH42 QC10

  5. #25
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    Quote Originally Posted by rzbill View Post
    This might seem perverse to some, but without the pressure to succeed or pass the test, I might enjoy the challenge of that sim situation that requred 2 pilots active on the yokes. Somewhat like the desire to fly the shuttle sim before it was decomissioned (and being envious of friends that were able to do it)
    Thanks for sharing that bit of experience.
    The sim is always fun when it isn't a jeopardy event, and a cursed, sweared at contraption when it is.

  6. #26
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    Quote Originally Posted by rzbill View Post
    Unfortunately too often true. Another recent example is VW Deiselgate.
    Space Shuttle Challenger O-rings. People probably should have gone to prison for that.

    https://www.nasa.gov/centers/langley...quium1012.html

  7. #27
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    Latest I have heard (newsfeed) is that the pilots DID operate "the switch", but they were still not able to recover. That suggests the excess trim the MCAS was capable of exceeded the authority the regular control has. The MCAS was apparently capable of several times the original adjustment total amount.

    In that case presumably they would have had to switch the system on, dial back the trim, and switch it off again, since the assertion is that switching it off kills the trim adjustment capability. I have no idea if that is true, but it sounds odd.
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  8. #28
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    From what I read on airliners.net, the pilots on ET302 followed procedure to disable autopilot (and MCAS), to use the manual trim wheels, but the plane was flying so fast that the wheels could not restore trim because of aerodynamic forces. That was the end of the checklist for runaway electric trim, and they could not control the aircraft. They were also pulling hard on the yoke attempting to counteract the nose down condition caused by MCAS, as well as giving almost maximum thrust for the same reason, but that also increased air speed beyond safe limits. If they had fully understood the operation of MCAS, they could have used the manual electric trim adjustment that might have saved the plane, and they did finally switch it on, but by that time it was too late. They were only about 5000 feet above terrain, losing altitude at maybe 300 ft/sec, and also perhaps attempting to execute a banked turn to return to the airport, so they had only 15-20 seconds to act, with unresponsive controls. Their fate was sealed. Tragic.

  9. #29
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    Well, at least for once, a company that made what should of been a standard option from the get go, an added cost, ended up costing them billions. Talking about the backup system to a single AOA sensor being used. Amounts to if a car company charged extra to have a left and right blinker instead of just a left blinker.

  10. #30
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    Quote Originally Posted by RB211 View Post
    Well, at least for once, a company that made what should of been a standard option from the get go, an added cost, ended up costing them billions. Talking about the backup system to a single AOA sensor being used. Amounts to if a car company charged extra to have a left and right blinker instead of just a left blinker.
    What about the airlines that decided "Nah, we don't need that"? No blame to them?

    At least one of the two airlines involved seems to have happily flown an aircraft that had one of the sensors known to be defective, and to have been defective for some time (the first aircraft to crash, Lion Air 610).
    1601

    Keep eye on ball.
    Hashim Khan

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