Night Hawk From Australia, joined Jul 1999, 273 posts, RR: 0 Posted (8 years 8 months 1 week 6 days 10 hours ago) and read 3294 times:
I work at Perth Airport in Australia and one day I was driving past the back of one of Qantas's A330's and noticed all the control surfaces (aileron's & elevator's) were angle'd down, and the rudder fully deflected to the left. Im wondering what the story is with that? The aircraft was parked at the gate with the APU running if that means anything.
Troubleshooter From Germany, joined Feb 2005, 423 posts, RR: 5 Reply 1, posted (8 years 8 months 1 week 6 days 8 hours ago) and read 3273 times:
You´ll see that on all fly-by-wire aircraft. If there is no hydraulic pressure on the flight controls, the ailerons and elevators go down due to their own weight. The rudder is deflected by sidewinds. All actuators are dampened to prevent flutter in high wind conditions. As soon as hydraulics are on, all flight controls will move to their commanded position (they will center if there is no trim input).
Troubleshooter From Germany, joined Feb 2005, 423 posts, RR: 5 Reply 3, posted (8 years 8 months 1 week 6 days 5 hours ago) and read 3223 times:
thanks for your info on the 747. I don´t see them very often at our airport, so I didn´t know that. I just tried to point out that "hanging" flight control surfaces are a common finding on all FBW aircraft. Which doesn´t mean that this is not valid for conventional airliners, too.
HorizonGirl From Canada, joined Mar 2005, 804 posts, RR: 16 Reply 5, posted (8 years 8 months 1 week 5 days 20 hours ago) and read 3148 times:
I have always wanted to answer this!
this will happen mostly on Fly-By-Wire aircraft.
As soon as there is no pressure, the Control surfaces will
"droop." and as VC-10 said, this will also sometimes happen on
Jetlagged From United Kingdom, joined Jan 2005, 2508 posts, RR: 24 Reply 6, posted (8 years 8 months 1 week 5 days 9 hours ago) and read 3106 times:
I suppose you could say the 747 was fly-by-wire, in that the control signals are carried to the actuators by (mechanical) cables
Any aircraft with fully powered, irreversible flying controls will have suffer this kind of surface droop if the surface is not balanced.
On aircraft with manual or boosted controls, the surfaces may even go fully up, due to out of balance masses. Control locks are generally fitted on these aircraft to stop the surfaces being damaged, especially by tail winds, which can slam them between full down and full up.
The glass isn't half empty, or half full, it's twice as big as it needs to be.