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Aikon
1st Oct 2008, 16:47
Is it possible or is it just not recommended to do cross control on airbus fbw?

If so, can anyone tell what is the reason behind it?

Thanks.

gatbusdriver
1st Oct 2008, 16:53
Yes it is possible. As for why it is not reccommended, I don't know.

kijangnim
1st Oct 2008, 17:49
Greetings,
Theoratically you cannot cross the controls, however, like someone pointed out you can by ordering a roll, release the joy stick then apply opposite rudder, the problem is that there will be too much stress on the fin :ok:

Cardinal
1st Oct 2008, 18:28
If you're trying for a wing-down method crosswind landing you don't need hardly to cross control. Add downwind rudder and the upwind wing will miraculously and proportionally come down without pilot intervention. I don't know why it works, but it certainly seems to. Ask Toulouse :)

Chris Scott
2nd Oct 2008, 10:59
Hi Aikon,

It may be that the control laws have been modified since I last flew the A320 in 2001, but I never experienced the automatic sideslip that Cardinal describes above.

See if this − and posts from many contributors on the same thread − make any sense:

http://www.pprune.org/tech-log/316096-lh-a320-rough-landing-hamburg-24.html#post3979423 (http://www.pprune.org/tech-log/316096-lh-a320-rough-landing-hamburg-24.html#post3979423)

I’m referring particularly to the paragraph “Crosswind Landing”. Prolonged flight in sideslip may not be practicable or desirable on FBW Airbuses, probably because of the roll-yaw coupling feature.

Chris

Halfbaked_Boy
2nd Oct 2008, 11:18
Hmm, I seem to recall Airbus changing certain regs and advisories following an accident involving crossed controls and a damaged tail fin? That's about all I can remember, can anybody shed more details?

Jack

hetfield
2nd Oct 2008, 11:58
Crosswind landings
The preferred technique is to use rudder to align the aircraft with the runway
heading during the flare while using lateral control to maintain the aircraft on the
runway center line. Routine use of into wind aileron is not recommended, because
sidestick deflection commands roll rate until touchdown.
In strong crosswind conditions, small amounts of lateral control may be used to
maintain wing level. This lateral stick input must be reduced to zero at first main
landing gear touchdown



http://www.aaib.dft.gov.uk/cms_resources/dft_avsafety_pdf_507757.pdf

Aikon
3rd Oct 2008, 07:21
Thanks guys. It is much clearer to me now. This is such a wonderful forum where a lot can be learned from each other.

And a special thanks to Chris for pointing me to an excellent thread with so much info.

Well done guys!