QAVION

Airplane loss of control aside, is it possible to pull the speedbrake lever on a 737NG through the flight detent to the UP position in the air?

In the manuals I've read, there is no mention of an electric locking mechanism as such (as found on, say, the B747-400), to prevent you pulling the lever through the FLT DETENT. There is only the mention of a detented cam.

I understand the fact that the ground spoilers will not activate because of a mechanical interlock with the undercarriage, but will the flight spoiler panels extend further in the UP position in flight?

Thanks.
Regards.
Q.

Phoenix_X

Well, Boeing published a OB stating that to prevent high vibrations and damage to the stabiliser, pilots should not pull the speedbrake lever beyond the FLT detend. You can actually do it, and worse, judging from the OB, people have.

comxtek

No, there is nothing mechanical preventing the speedbrake lever from being pulled to the full-extended position.

And Phoenix X, the bulletin wasn't for extending the speedbrakes beyond the flight-detent. The bulletin restricts the use of speeedbrakes -period- until the elevators tabs are replaced on those affected aircraft.

QAVION

Thanks, guys.

Cheers.
Q.

Phoenix_X

Comxtek, there was a bulletin issued before the one restricting speedbrake use above 300 kts.
That one said don't use speedbrakes beyond the FLT detend until a vibration incident has been investigated. The result of that investigation was the 300 kts restriction and stab modification.

Bumblebee

Can you clarify..?...Does this 300kt restriction apply to just the NG? or the 3/4/5 aswell...?

comxtek

The problem only applies to the B737 Next Gen aircraft. It started as a problem on the -900s, but it was later learned that it existed in the -700/800. It was fixed on the -900 by adding a stiffer elevator tab. The -700/800s already in service have to be retrofitted w/this stiffer tab before the restrcition is lifted.