Night Hawk From Australia, joined Jul 1999, 273 posts, RR: 0 Posted (8 years 1 month 2 weeks 2 days 13 hours ago) and read 2914 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 1 month 2 weeks 2 days 11 hours ago) and read 2893 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 1 month 2 weeks 2 days 8 hours ago) and read 2843 times:
VC-10,
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.
CCA From Hong Kong, joined Oct 2002, 707 posts, RR: 14 Reply 4, posted (8 years 1 month 2 weeks 2 days ago) and read 2774 times:
Quoting Troubleshooter (Reply 1): the ailerons and elevators go down due to their own weight.
You'll find the 747 Outboard Ailerons and elevators rarely droop under their own weight as they are balanced. ie they have weights forward of the hinge equal to the weight aft of it.
HorizonGirl From Canada, joined Mar 2005, 782 posts, RR: 17 Reply 5, posted (8 years 1 month 2 weeks 1 day 23 hours ago) and read 2768 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
other aircraft.
Jetlagged From United Kingdom, joined Jan 2005, 2452 posts, RR: 17 Reply 6, posted (8 years 1 month 2 weeks 1 day 11 hours ago) and read 2726 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.
VC-10 From United Kingdom, joined Oct 1999, 3677 posts, RR: 37 Reply 7, posted (8 years 1 month 2 weeks 1 day 8 hours ago) and read 2680 times:
Quoting CCA (Reply 4): 747 Outboard Ailerons.............. rarely droop under their own weight
With the flaps up the Otbd Ailerons are locked in the neutral postion. One of the first indications of a failed lock out mechanism is a drooping Otbd Aileron
B747FE From Hong Kong, joined Jun 2004, 230 posts, RR: 4 Reply 8, posted (8 years 1 month 2 weeks 1 day 6 hours ago) and read 2655 times:
Night Hawk
Regarding the A330 ailerons, they would droop to 10 as soon as the flaps are in 17 (ECAM indication 1+F). Not likely when the aircraft is at the gate, unless maintenance was inspecting it.
Quoting CCA (Reply 4): 747 Outboard Ailerons and elevators rarely droop under their own weight as they are balanced
Yes, they are balanced surfaces, but the lockout mechanism is activated when the leading edge flaps are retracted.
Regards,
B747FE.
"Flying is more than a sport and more than a job; flying is pure passion and desire, which fill a lifetime"
CCA From Hong Kong, joined Oct 2002, 707 posts, RR: 14 Reply 9, posted (8 years 1 month 2 weeks 1 day 2 hours ago) and read 2609 times:
Quoting CCA (Reply 4): 747 Outboard Ailerons and elevators rarely droop under their own weight
Sorry what I should have added is under nil wind conditions, because if it's windy they could end up full up or down just like the rudder moves, balanced surfaces won't fall under their own weight.
Also the lockout has no effect it's mechanical and just prevents the outboard aileron inputs reaching the actuator so once hydraulic pressure is removed it may move after some time due to the wind.
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