Fresh setback for Boeing's 737 MAX

There are degrees of gullibiltiy. Cursitor Doom will beleive any right-wing nonsense, and John Larkin wil believe any climate change denial propaganda .

Krw believes a lot of similarly nonsencial things, but he isn't actually gu llible - he can't absorb any kind of new idea, and the nonsense he now bele ives all dates back to the time when he could still learn stuff, back when Joseph MacCarthy still had credibility.

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Bill Sloman, Sydney
Reply to
Bill Sloman
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I remember when you "quit" this group because there was not enough posts ab out electronics. You lectured the group about how boring the group had beco me (or some such thing) and you are and have always been the creator of tro lling content [actually it is not really trolling content because nobody bi tes on it]. Not that I mind off topic stuff or trolls, I think it adds to a n otherwise narrowly focused group.... I am just saying that I remember you r high and mighty Opus......what i can't remember is how long it lasted.

Reply to
bulegoge

Of course, that's why I said I don't know how you can say that the system was engineered properly. The manual hand crank system has been in 737s since they first rolled out and from all indications, if those planes suffered a runaway trim that put the plane into a steep nose down, it would be difficult to impossible for the pilots to be able to manually turn the wheels and to do so in time to avoid a crash too. I would assume that the reason we haven't seen crashes before is that true runaway trim is very rare.

That is runaway trim. Trim, where for whatever reasons, the system that uses electric motors runs has a failure that causes the trim to go to some incorrect position.

The point is that they do not work fine if the trim runs away to a steep nose down setting. We have the Ethiopian crash that, by all indications, shows that. We also have Sully saying that he had trouble trying to recover in a simulator from the same situation, even knowing what was coming. Once the trim runs far enough and the plane is pitching down and gaining speed, it becomes near impossible or impossible for the pilots to get it back to where it needs to be quickly enough or even move it at all.

And again, had any of those earlier planes suffered a stuck switch or a short, that caused the electric motors to force full nose down trim, it would have produced the same result as the MCAS failure doing it. Actually, a worse result! Because with MCAS, the electric trim still worked, the pilots could use the trim buttons to undo what MCAS just did. With a short running the electric motors full nose down, the pilots would have had no electric option to reverse it.

Exactly. But that doesn't mean that it could not have. It just means we were lucky. And Boeing knew that too. In the early 737 manuals they described the procedure to deal with that, ie the case where the trim forces hard nose down and the trim wheels can't be turned. The manual said the procedure was to push the controls forward, the opposite of what you would normally do, which would help relieve the force required to turn the trim wheels. Over time that was removed from the manuals.

Reply to
trader4

Agree, I haven't seen anything where it's been stated that the difficulty in turning the trim wheels is worse with the MAx than any other 737. And only one crash, Ethiopia, was apparently due to that. No indication that the Lion Air flight the pilots even followed the runaway trim procedure and tried to trim manually.

Reply to
trader4

I agree it looks like that is why ONE crash, the Ethiopian one, was unrecoverable. There the co-pilot said he was trying to move the trim, but could not do so. It's not absolutely clear what he was doing and what he meant, but it looks like he was trying to turn the trim wheel manually and could not move it.

The other crash, the crew was just lost in the wilderness. AFAIK, there is no indication that they even followed the runaway trim procedure at all. They flew around for about 5 minutes, with MCAS commanding nose down, then the pilot reversing it with the trim buttons. The plane could have flown for hours like that, until it ran out of fuel, but the pilot handed control over to the co-pilot and when MCAS did the next nose down, the co-pilot only applied a weak nose up and then nothing more. Had they used the trim buttons as they were doing to get the trim near where it should be, then followed the runaway trim procedure, turn off the switches and trim manually, the plane would have flown fine. That's pretty much what happened the day before with the same plane.

I also haven't seen anything where it says that the difficulty of using the manual wheels is worse in the Max than previous 737s. I have seen where Boeing recognized from the earliest 737s that with enough nose down runaway trim, the wheels might be difficult to impossible to move. They described a procedure in the manuals for pilots to push forward on the controls, which would temporarily make the dive even steeper, but would relieve some of the pressure from the control surface and make the trim wheels easier to turn. That process was later dropped from the manuals, has been gone for decades.

Reply to
trader4

I've one guy talk about FAA might also be looking at the 737NG because when it was made the trim wheels were made smaller than on the classic 737 to make room for the instrumentation upgrade

Reply to
Lasse Langwadt Christensen

On Tuesday, July 2, 2019 at 2:06:18 PM UTC+2, snipped-for-privacy@columbus.rr.com wrote :

about electronics. You lectured the group about how boring the group had be come (or some such thing) and you are and have always been the creator of t rolling content [actually it is not really trolling content because nobody bites on it]. Not that I mind off topic stuff or trolls, I think it adds to an otherwise narrowly focused group.... I am just saying that I remember y our high and mighty Opus......what i can't remember is how long it lasted.

Whoever Bulegoge is, he hasn't got enough sense to include enough of the po st he's reacting to make it clear who it is.

I had to go to eternal september to find out that he was talking about me.

I do remember taking a break from the group a year or so ago. I don't recal l saying anything about electronic content or trolling at the time - perhap s Bulegoge could use Google to find the post?

I suspect that his memory is playing him false. Since he doesn't ever seem to have ever posted anything worth paying attention to - I certainly can't recall anything - I really shouldn't have bothered responding to this worth less crud either.

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Bill Sloman, Sydney
Reply to
Bill Sloman

** I agree - posters who use stupid handles and post abuse in mid air ( no context or quotes ) are the worst kind of trolls.

IMO that makes them fair game for anything you are to say about them - so I do. And don't little s**ts squeal about it.

.... Phil

Reply to
Phil Allison

Chris wrote in news:qfdgmk$td9$1 @gioia.aioe.org:

the

in

Boeing

The system I suggest RELEASES MCAS and dials from the cockpit using cockpit installed MOTORS, which are more powerful than humans. IF that fails or is also 'down', THEN the pilot uses the dials.

And YES THEY (cockpit stab trim dials) WERE around BEFORE the MCAS system.

STAB TRIM has been around for DECADES.

Reply to
DLUNU

Chris wrote in news:qfe6u9$2ev$1 @gioia.aioe.org:

Roller coaster is not was not NEVER was a "method", ya dope. It is a description of what was recovered from not the method of recovery.

It is an outcome of a control method (cockpit actuation) which has the HUGE problem of being too slow, and the loading increases on ALL craft experiencing such an issue.

Reply to
DLUNU

onsdag den 3. juli 2019 kl. 01.58.41 UTC+2 skrev DLUNU:

from the horses mouth,

formatting link

Reply to
Lasse Langwadt Christensen

Lasse Langwadt Christensen wrote in news: snipped-for-privacy@googlegroups.com:

Sounds like a better screw thread design should have been used. Sounds like good ol' square thread was chosen by the $9.00 'engineers'.

Should have used precision caged ball screw assembly for the least back force imposition while having a high transition per turn rate.

Reply to
DLUNU

snipped-for-privacy@columbus.rr.com wrote in news: snipped-for-privacy@googlegroups.com:

Damn. This guy is so stupid, he not only does not even know what a troll is, the dope thinks that he DOES!

Dude... YOU are the troll.

Reply to
DLUNU

The "roller coaster" method he's referring to is Boeing's method for extreme runaway trim recovery that was in the 737 manuals decades ago. If the trim goes far out the pilots may not be able to turn the trim wheels manually. So the procedure was to push the controls forward, put the plane into a steeper dive to relieve the pressure so that the trim wheels could be turned.

Reply to
trader4

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

Simple solve with the cockpit assist motors.

The problem is with the speed of actuation. Period. Subsequent difficulty in manually turning the dials and doing so in a timely manner. Not possible, as we have seen demonstrated tragically.

Hence the cockpit assist motor suggestion.

We already know what happened, yet you guys keep coming back spouting off what you read as if no one else did.

So, What The Fuck Is up with That?

Reply to
DLUNU

snipped-for-privacy@optonline.net wrote in news:b6ce2956-2152-498c-9d9f- snipped-for-privacy@googlegroups.com:

Got you pegged. A copy and paste savant wannabe. With plenty of your own bent perspective sprinkled in.

Reply to
DLUNU

Lasse Langwadt Christensen wrote in news:7df5b14a- snipped-for-privacy@googlegroups.com:

Hand application of torque on smaller wheels is more difficult than on the larger diameter.

The connection of said wheels to whatever actuation shaft matters too. Is there a ratio, etc.

Reply to
DLUNU

Phil Allison wrote in news: snipped-for-privacy@googlegroups.com:

Which actually makes you worse than the trolls. Doh!

Reply to
DLUNU

Which then introduce their own potential failure scenarios. And if this is a problem in the Max, then it's a problem in all

737s. Are you proposing they all be retrofitted, when there are other measures being implemented to prevent MCAS from causing runaway trim? Once that is done, the Max should be no more likely to experience runaway trim than any other 737.

It's obviously possible, that was proven by the crew on the LA flight the previous day. Same thing happened, the pilot just riding in the jump seat had to tell the other pilots what to do, ie follow the runaway trim procedure. They did and the plane flew on to it's destination.

Also, the LA flight that crashed, had they followed the runaway trim procedure that plane would not have crashed either. They flew around for about 6 mins, using the trim buttons to counter what MCAS was doing. They never did the runaway trim procedure, but the flight profile suggests that had they done it, it would have worked as it did the day before.

You keep making incorrect assertions?

Reply to
trader4

snipped-for-privacy@optonline.net wrote in news:513bbc83-4475-4460-90dd- snipped-for-privacy@googlegroups.com:

Only one. It not energizing when the pilot flips the switch.

As I said, the pilot hand method is the last resort.

All systems have failure modes and many are virtually unrecoverable.

So MULTIPLE systems get introduced.

Nit pick BS.

Reply to
DLUNU

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