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Boeing advice on "aerodynamically relieving airloads" using manual stabilizer trim

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Boeing advice on "aerodynamically relieving airloads" using manual stabilizer trim

Old 14th Mar 2019, 14:41
  #21 (permalink)  
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You are probably right - Dorval, not Toronto. It happened in the early 1960s and I believe the wrong grease was the cause. I knew the captain, a good pilot and a good bloke.
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Old 14th Mar 2019, 21:11
  #22 (permalink)  
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Originally Posted by LeadSled View Post
I don't know where this comes from, but with a jammed/frozen stab on the B707, you simply trimmed by splitting the spoilers, and at lower speed, splitting the flaps ---- one of the lesser advertised benefits of a swept wing.
There was no need for any so called "yo-yo" maneuver.
It is true of the B707 that full elevator deflection could stall the stab, and you had to reduce the aerodynamic load on the stab by reducing the elevator deflection, which you wouldn't want to do close to the ground, if it meant lowering the nose.
So: On the overhead panel, about the Captain's right eyebrow, Spoiler Switch UP, and pull the Speedbrake as required. The rule was: Switch UP, pitch Up, Switch Down, pitch Down ( except on G- registered aircraft, where D.P.Davies buggered it up, as usual).
Yes, doubt any pilot or F/E rated on the B707 could forget the splitting of spoilers (and, for the approach, the flaps) for pitch control in the jammed-stabiliser case. But I'm not familiar with the layout of spoilers on the wing of the seven-THREE, or if they can be split in the same way. We need a rated B737 pilot to comment...

Originally Posted by LeadSled View Post
I will be fascinated to find out what the realm problem is with the speed stability system on the Max --- anybody who flew them cast your minds back to the A310 and A300-600, and aircraft losses.
Not sure what you are specifically referring to. I did (only) two years P1 on the A310 35 years ago, and my main recollection of significant trim (THS) contingencies relates to the G/A situation - with or without AP. The auto-trim with AP engaged was, IIRC, slower than manual THS trimming, so the yoke remained forward for a longer period. But I'm not aware that the large amount of down-elevator required in either case ever led to the THS stalling.

It seems unfortunate that, faced with unexpectedly strong competition from the A320 family (first certificated in 1988), Boeing decided to exploit the grandfather certification rights of the B737 rather than introducing an all-new type.
Chris Scott is offline  
Old 15th Mar 2019, 04:07
  #23 (permalink)  
Join Date: Jul 2001
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Chris Scott,
Specifically the trim pitch up (instead of reducing power by retarding the thrust levers) to prevent exceeding limit speeds, and pilots fighting the pitch up trying to maintain assigned altitude, with autothrottle engaged.. When it all came apart, violent pitch ups exceeded 35 or more degrees, from memory.
There is a spectacular video of a A 310 over Paris, the pilot had to roll it on its side to get the nose down, that actual aircraft was later lost in what was thought to be similar circumstances some time later. At least he understood he could never just get the nose to pitch down by pushing.
There was an A 310 lost on approach at Nagoya, that was a close one for Qantas, there was some discussion about an immediate t/o for QF, they got it, and the A310 finished up about where the QF B747 has been holding.
I well remember, at the time, ANG (PX)) banning any coupled missed approaches ---- but that was back in the day when we could ALL fly --- and were expected, so to do. I thought it was a very wise decision on behalf of m' old mate, their boss of training. the best way of eliminating mode confusion is eliminate the modes as required.
What I do know about the B737 (up to NG) is that the stab trim cutout switches are in exactly the same position as every other Boeing aircraft I have flown, and that is a few. I would bet the Max is the same.
The crew of the Lyon Air "the night before" from Bali demonstrated what was possible with their particular set of defects.
Tootle pip!!

Last edited by LeadSled; 15th Mar 2019 at 04:19. Reason: minor text change.
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Old 18th Mar 2019, 16:40
  #24 (permalink)  
Join Date: Feb 2003
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[COLOR=left=#000000]We learned all about these maneuvers in the 1950-60s. Yet, for some inexplicable reason, Boeing manuals have since deleted what was then - and still is - vital handling information for flight crews.[/COLOR]
The "inexplicable reason" is, I understand, input from Boeing lawyers as a reaction to Product Liability law. Lots of good stuff was removed from the B737-200 manuals in the 80s, not just what Centaurus describes, but also advice on (for example) landing with partial gear. I was flying the 737-200 at the time and was unimpressed by the deletion of useful advice.
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