Another classic pilot;mechanic exchange

[oldtimer]

The Sunwing Airlines Inc. Boeing 737-800 aircraft (C-FLZR, FLT 1540) was climbing through 3000 feet ASL when the crew noticed the STAB TRIM was not responding with autopilot selected. As the aircraft increased airspeed it began to pitch nose down. The captain took control, manually trimmed the aircraft and declared a PAN PAN and returned to Dublin. The landing was uneventful with ARFF standing by. Maintenance was called on board and found both STAB TRIM switched in the off position. The operator has initiated their own investigation into this event.


How many times has this happened?
Does the word "CHECKLIST" come to mind?
Can any B737 pilots tell us if the airplane has a manual trim wheel like smaller airplanes.

[doorhandle27]

If electric trim wasn't working, the checklist would call for selecting the trim switches off before commencing manual trim. At least that was the 727 procedure and the 37 has a similar system. If you've ever seen anyone in the sim get smacked by a trim wheel handle you'll understand why those switches are selected off.

Those are my thoughts, the crew would've set their stab trim prior to leaving the gate, meaning I bet those switches were on to begin with.

[oldtimer]

This blurb was sent to me by a friend. It must have come from the Irish version of CADORS and it is quite obvious there is not enough information to make an informed decision but the first thought I had was from personal experience, mostly watching from the sidelines, where a crew returned to land because of a problem that was a very easy fix, something simple troubleshooting could have remedied.
It is good to hear from people who are familiar with the type and can give a more informed opinion.
Metro pilots will be familiar with the emergency hydraulic selector valve on the floor. Kick it forward getting into the seat and the main hydraulic system is bypassed. Ever had a crew return to the ramp because they could not get nose wheel steering or get the flaps down? The mechanic comes out and resets the valve and everything works just fine.
Then again I read about a crew who returned because of what appeared to be a simple problem (Gen Fail) but it turned out they averted a disaster. (Gearbox about to munch).

[C1-17]

I'd say its a little early to hang these guys. You want those switches off before extending the manual trim wheel handle. The electric trim doesn't care if your hand or knee is in the way. If they departed with both trim switches off and didn't figure it out, then ya, they screwed up.

[Mohawk]

Isn't it a pre-departure check to run the trim electrically for both maintenance and the crew??? I am having a hard time the crew didn't check the trim!

[tbaylx]

Isn't it a pre-departure check to run the trim electrically for both maintenance and the crew??? I am having a hard time the crew didn't check the trim!

Not only that but you have to set the T/O trim and I don't know too many people who do that manually without running the electric trim.

[tbaylx]

Isn't it a pre-departure check to run the trim electrically for both maintenance and the crew??? I am having a hard time the crew didn't check the trim!

Not only that but you have to set the T/O trim and I don't know too many people who do that manually without running the electric trim.

[xsbank]

Read it again - the autopilot would not trim the stab. Autopilot disconnected, manual control, returned to land.

Autopilot issue. "Manually trimmed" may still mean electric trim, but he used his thumb.

And the controversy is.....?

[iflyforpie]

Read it again - the autopilot would not trim the stab. Autopilot disconnected, manual control, returned to land.

Autopilot issue. "Manually trimmed" may still mean electric trim, but he used his thumb.

And the controversy is.....?

But something doesn't add up there.

Trim doesn't respond to autopilot inputs, so they disconnect the autopilot and use the thumb switches to trim. Why is the STAB switch off then?

If they realized the autopilot wasn't controlling the trim, then used the thumb switches and realized they didn't work either (because of a common problem with the trim system), then disconnected the stab, deployed the handles, and trimmed manually, and left the stab disconnected, that would make sense.

If the trim switch was off the whole time, how did they set trim for takeoff?

[sstocker31]

I had this happen to me climbing through 10000' I selected the autopilot on and a few minutes later the stab trim light illuminated. it turned out that the autopilot side of the stab trim switch wasn't fully in the on position, but the manual electric trim side was.

[True North]

Trim doesn't respond to autopilot inputs, so they disconnect the autopilot and use the thumb switches to trim. Why is the STAB switch off then?

Maybe not in your airplane but it does in the 737.

[CID]

This thread serves no useful purpose. All it's doing is ruffling the feathers of people who think they know something.

[iflyforpie]

Maybe not in your airplane but it does in the 737.

What does?

[True North]

Maybe not in your airplane but it does in the 737.

What does?

Stab trim responds to autopilot inputs.

[TOGA Party]

He phrased it strangely initially, but I think he knows that.

[iflyforpie]

Maybe not in your airplane but it does in the 737.

What does?

Stab trim responds to autopilot inputs.

Oh, I see. I meant to say '[Because of a problem] trim doesn't respond to autopilot inputs'.

[Meatservo]

Why is this a "classic pilot/mechanic exchange"? I have yet to read anything about any conversation between a pilot and an engineer here, let alone anything entertaining or "classic".

I was expecting something like the old gag where the pilot snags the autopilot and the engineer makes a logbook entry that says "replaced meat servo with functioning unit; tested serviceable" when another pilot test flies it and finds nothing wrong. Or the pilot snags the left engine for an oil leak, and the engineer writes "oil leakage normal", and then the pilot writes "right engine missing normal leakage".

You know, something like that. This thread is stupid and has nothing to do with any exchange between a pilot and a mechanic. Come up with something interesting for gods' sake.