Yaw Dumper Hard Over

[New on NG]

I´lll have a simulator session with this maneuver and i could not find this isue in my manuals. Any clues???

[ZSLHF]

I performed the manoevre yesterday in the sim. Yep, there is little info in the books. The recovery technique that worked for me was to:

1) Look where the sky pointer is on the ADI, i.e. left or right, and throttle to idle the same engine (you are reducing the yaw created by the rudder by throttling back the opposite engine)
2) At the same time pick up the wing with ailerons.
3) At the same time get some speed by descending (you'll be descending rapidly already anyway).
4) Suggest you don't throttle back the remaining engine to descent, as that engine helps keep the aircraft under control.
5) And of course, at some stage, follow the Quick Reference Handbook for Uncommanded Yaw etc etc

Although we were supposed to land with flap 15, for demo purposes a successful flap 30 ILS approach and landing was performed, but kept the speed at 150k.

The aircraft of course will be flying very much cross-controlled till touch down (nose wheel will also not be aligned with runway)

[FlapsOne]

You mean a rudder hardover not a yaw damper hardover...........don't you?

What aircraft type?
What does your QRH, or equivalent document, say?

Give a bit more info and we'll try to give a bit more help.

[Medwin]

I'm sure its a hardover protection not a yaw DUMPER flapsone.

[junior_man]

Most important thing is to unload the wing. Push forward on the yoke. This will make the ailerons more effective and allow you to use them to stay right side up.
Beware of using differential thrust. Okay if you have time to think about it. Fatal if you make a mistake. Unloading the wing will give you enough aileron to control the aircraft.
Once it is undercontrol, get out the QRH and run the procedures yaw damper off, stby rudder etc.

[BOAC]

The most worrying thing is that 'new on NG' says there 'is nothing in the manuals'.

If he/she is with an airline, then the manuals SHOULD be available. If not, the airline is in default of its responsibilities and should be reported to the authority in Brazil (or he/she needs to look harder!). If undergoing some training course with an agency, likewise.

A fair time ago Boeing published an amendment to the QRH for Classic and NG 737 which covers just this situation.

[junior_man]

If he is in the NG 737 there may not be a procedure, it is supposed to have a different PCU design.

[BOAC]

I would assume the 'Uncommanded Rudder/Yaw or roll' item should cover?

[capt kickback]

In the latest ammendment to the B737NG QRH all recall items for the uncommanded rudder have been removed, as boeing believe that this problem has been ironed out and it will not happen AGAIN??.......work that one out??

[BOAC]

Cpt kb - could you pse give me the date/ref of that amendment?

[Old Smokey]

I'm not current on the B737 any more, but the 'generic' procedure for dealing with a Yaw Damper 'Hardover' is to treat it like an engine failure without the performance loss.

That is, oppose the yaw with rudder, pick up the dropped wing with roll control, and then adjust rudder and roll input for stable flight. After picking up the dropped wing with roll control, zero or very little further roll input should be needed, but sustained rudder pressure will be required until either the Yaw Damper is de-activated, or rudder trim applied.

Regards,

Old Smokey

[New on NG]

Old Smokey is right and to boac my revision is nº 14 for Classic and NG . i fly both of them. Maybe i could not make mysel clear. I could not find in my manuals the term yaw dumper hardover.

[BOAC]

Thanks n-on NG - do you have a revision date for that issue?

[junior_man]

This is from memory:
reduce angle of attack, this is necessary if you are near or below crossover speed May take full aileron to maintain level flight.
Auto pilot off
Auto throttle Off
Yaw damper off
Either A or B flight controls to standby rudder.

The standby rudder PCU is stronger than either the A or B rudder PCU and can overpower a hard over PCU.
Plan 15 flap landing

Airbus driver right now. Been on the -200, -300 & -400 for a number of years.
Don't screw around with the throttles. Wrong one and you die. Besides, you need the power so you don't lose altitiude (that said don't try to hold altitude in the recovery) Switch flight controls to stby rudder and problem will go away or at least be overpowered by the stby PCU.