Boeing 737 Max design error

That's true, but the simple solution to that is the pilots could have used the trim buttons to get the trim back close to neutral and then turn off the electric trim. Even you should be able to understand that.

And how many more failure modes do you think that will introduce, trying to solve a problem that Boeing already has the solution to? All planes with electric trim are subject to possible runaway trim. That's why it's supposed to be understood and committed to memory. Sadly, most of these pilots couldn't identify it or deal with it. But if using the mechanical trim was such a big problem and serious issue, it's rather odd that we all the accident data, it hasn't shown up as being significant, or at all. Even these crashes, if the pilots had correctly identified the runaway trim problem and responded, there would have been no crashes. For proof of that we have the one flight the day before with LA.

Reply to
trader4
Loading thread data ...

snipped-for-privacy@optonline.net wrote in news:c3425dd2-d12c-46e5-a123- snipped-for-privacy@googlegroups.com:

I do not need a primer from an illiterate #350+ lard ass, traderTard failure.

Stay the f*ck off my posts, you 20 IQ dumbfuck.

Reply to
DecadentLinuxUserNumeroUno

I said *altitude*, not attitude.

Wrong, always wrong.

Reply to
trader4

Wrong always wrong. I always said attitude and airspeed. You just can't read, thought I said "altitude" in a post you replied to. I corrected you there too.

Wrong, always wrong.

Reply to
trader4

For guys like you we have the cutter offer option. A giant shear that severs it.

That

Without power assist, you could not move most of the control surfaces, including the trim, in large aircraft, eg 737s.

The pilot

Like I said, for you, the cutter offer.

Always wrong, and most times like this silly too.

Reply to
trader4

Yes and in the case of these incidents, easy to do too, with the trim buttons on the yolk. We have flight data for many minutes of flight, where the pilots did exactly that as they counteracted what MCAS did.

Reply to
trader4

snipped-for-privacy@optonline.net wrote in news: snipped-for-privacy@googlegroups.com:

Nope. I ALWAYS said attitude. I never said altitude. You are not merely full of shit, boy. You are shit.

You did it just today, in fact. You said that 'it seemed' to not be a factor. Then in another post after that you said it should be looked at.

Reply to
DecadentLinuxUserNumeroUno

I may be wrong, but I believe there is still hydraulic assist or similar to the jackscrew for a number of reasons, one of which is that you could not exert enough force to turn it by hand. I think the electric cutoff to the trim disables a small motor that moves the trim wheels, which in turn drive the motor that moves the jackscrew.

That's for sure.

Reply to
trader4

Bingo. And to fix a mostly non-existent problem. It's almost certain that another add-on, which would add cost and complexity, would reduce reliability, not increase it. Electric trim, the cutoff switches, trimming manually has been around for a very long time and I'd like to see data that shows what he wants would have made any difference.

Reply to
trader4

We seem to be slowly evolving there.

We know that most of the pilots presented with runaway trim on the Max couldn't identify it and follow the simple procedure. One pilot for sure did, probably two, but two out of seven isn't very reassuring.

Reply to
trader4

Who mentioned trim tabs?

Anyway, I don't know where you're getting that from. Different aircraft use different arrangements for longitudinal trim. The trim on a 737 works by adjusting the tailplane.

It doesn't touch the elevators.

Sylvia.

Reply to
Sylvia Else

They already had an artificial horizon. The thing that was missing was any kind of sanity check on the validity of the AoA sensor output.

There was also a major discrepancy between what Boeing told the FAA MCAS would do in terms of how much adjustment and what it did in actuality. This is unforgivable at multiple levels. No-one will ever trust the FAA again outside of the USA. They were in bed with Boeing and prepared to keep planes flying they knew to be dodgy even after the second crash.

Finally Boeing have been forced to admit they knew about this problem and the AoA vulnerability more than a year before the first crash but had convinced themselves that it wasn't a safety critical problem.

formatting link

Apparently they said "it did not jeopardise flight safety" which is true in normal operation but completely untrue when the dodgy AoA sensor goes haywire and MCAS puts the plane into an almost unrecoverable power dive.

It is an example of the fix being far more dangerous than the original problem that it was supposed to address.

That said whilst the GPS system is working you also have some pretty good independent numbers for ground speed and rate of climb that are reliable and are referenced to an external reference frame. Airspeed indicators have been known to cause crashes when they malfunction too but they can also provide a sanity check against the risk of stalling.

I think there probably are flight configurations where you can pretty much rule out stalling altogether. Notably when the nose is pointing down and the plane is already gaining speed by losing height.

Since the problem only arises in normal flight mode I am surprised that the SOP for zapping MCAS misbehaviour on take-off was not to extend flaps again and increase engine thrust - then you get the benefit of full servo control of all the flight surfaces and MCAS is disabled.

I am sure that eventually the story will come out how this thing was certified as "airworthy" despite having such very obvious flaws.

--
Regards, 
Martin Brown
Reply to
Martin Brown

The trim wheels rotate very quickly when operated by the motor. I've taken this to be because the turn ratio has to be that high so that the pilots can turn it by hand if they need to.

Anything powered that is capable of rotating the jackscrew is going to have a potential failure mode where it rotates it when it shouldn't.

Sylvia.

Reply to
Sylvia Else

Which again brings us back to the question of why the recommendation if the thing goes haywire after retracting the flaps is not to extend them again and increase engine power again. MCAS isn't active when the flaps and lift enhancers are deployed for takeoff and landing.

Fuel economy is irrelevant when you are fighting just to stay in the air against an automated system that is trying to crash the plane.

--
Regards, 
Martin Brown
Reply to
Martin Brown

Yes, great idea. McDonald Douglas used that idea in the DC-10. Instead of a jackscrew to drive the flaps, they used a hydraulic PISTON. Which of course is what we actually call it. In 1979 a DC-10 full of passengers taking off from O'Hare had an engine fall off, which in turn damaged the hydraulic lines in the wing. The flaps retracted. Guess what happened next.

Wrong, always wrong.

Reply to
trader4

That's interesting terminology. Typically we have a pilot and co-pilot.

to affact whatever orders were

That is EXACTLY what is there now. In all these planes, the electric trim buttons on the controls were working and were used many times to move the trim back to where it should be. Is it rocket science to get it near normal and then turn off the cutoff switches? Geez.

They've already been flying for decades and so far, I've not seen a crash attributable to a fly-by-wire failure. If you have some to show us, please present them.

And if that's true, how over the last decades as more computer control and fly-by-wire have been deployed has aviation safety greatly improved?

Wrong, always wrong.

Reply to
trader4

This is also incorrect :)

There are no CoG problems with 737 Max 8, or stability problems, or anything else of that ilk which the press seem to be peddling with abandon. It is true that it has larger engines whch are mounted further aft and higher, but the essential problem is that the nacelles are larger and generate more lift, particularly at higher AoA. This compounds the pitch/thrust moment that the 737 classic is also known for, which is a tendency for the aircraft to generate higher AoA itself through thrust rather than control surfaces, although who knows if the higher engine mounting position actually ameliorates that by reducing the length of the moment arm.

MCAS is described as a safety feature, but all it was intended to do is ensure that at higher angles of attack, the elevator /feel/ does not change to make less elevator input force (stick back) required at high AoA. It is not designed to save the airframe in some way from bad piloting, in the same way that the stick-shaker stall warning won't cause thrust to be applied or nose-up command inputs to be made without the pilot performing those actions.

This is a fundamental point; the Max 8 is a completely new aircraft but with similar enough flight controls to the preceding 737 that aviation authorities, particularly the FAA, were willing to certify it as being flyable by existing pilots without major type training, or as it turns out, allow Boeing to self-certify large parts of a completely new design to that end. That the controls simply perform the same way as pilots are used to and are required by certain regulations was presumably a major consideration in the instigation of MCAS in the first place.

It is simply unfortunate that some people got too far out of their box and allowed the unit to have far more authority than it needed to perform that function, and the design was a piece of crap with single points of failure.

Reply to
Riley Angel

It is completely possible. A spin is a half-stall: The inside wing is stalled and the outside wing still has lift.

--

-TV
Reply to
Tauno Voipio

Wrong again. Anyone who has followed this knows that MCAS only works by using the trim. That is why Boeing put out the directive after the first crash, LA, to use the RUNAWAY TRIM PROCEDURE if MCAS screwed up again. And we know it works, the LA flight the previous day, the jump seat pilot told the dummies flying to turn off the trim, they did, they adjusted it manually, the plane flew on to it's destination.

Wrong, always wrong.

Thanks for further demonstrating that you're clueless about what trim is even about.

One thing is for sure, you're not normal. Wrong, always wrong.

Reply to
trader4

The simple alternative was to use the trim buttons to get the trim back to near normal, and only then turn off the electric to the trim motors. And these pilots had to know that their trim buttons were working, we have the FDR data showing they used those buttons many times and it worked. In the case of LA, they used them for close to ten minutes, before crashing. At any point, with the trim near neutral, they could have shut off the switches. And that didn't require knowing about MCAS or anything beyond the very basics of flying and the systems on any similar aircraft.

Yes, we call that the mythical cutter offer, just for you.

Wrong, always wrong.

Reply to
trader4

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.