worldoftui
Posts: 1054
Joined: Fri Aug 24, 2007 5:18 pm

777/767 Aileron Question

Tue Jun 15, 2004 11:03 pm

Having flown numerous times on 767/777, a question about the aileron useage.

Having read a previous thread that talked about aileron reversal (sounded kinda scary!), when do the outer ailerons become locked?

Does it happen when the flaps have been retracted? At a certain speed? At a certain height?

Also, I seem to remember something about the 767 inboard ailerons being deployed with the higher flap settings to "reduce the nose-up angle" on landing. Is this correct? Seem to remember them still functionning as they are deflected down, but how would this reduce the AOA?

Mark
 
cdfmxtech
Posts: 1319
Joined: Wed Jul 05, 2000 11:37 am

RE: 777/767 Aileron Question

Wed Jun 16, 2004 1:06 am

The Outboard airlerons on both aircraft are locked out as a function of airspeed (Lockout at cruise speeds).

The Inbd (Iand Outbd on the B777) Ailerons droop as a function of flap position. They droop increases as flaps increase. (Don't have specific numbers).

This droop is to assist the TE flaps.
 
worldoftui
Posts: 1054
Joined: Fri Aug 24, 2007 5:18 pm

RE: 777/767 Aileron Question

Wed Jun 16, 2004 1:09 am

This droop is to assist the TE flaps.

Forgive me, but "TE flaps? Trailing Edge?


Mark
 
DeltaGuy
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Joined: Wed Sep 12, 2001 5:25 am

RE: 777/767 Aileron Question

Wed Jun 16, 2004 1:14 am

Bout the only time I ever see them in use is on approach, as you're creeping along at 155-ish knots. In flight, it's all flaperons, and you'll see minor movements from them, resulting in larger roll movements...amazing how effective they are.

As said, they are inhibited by airspeed, I think they become effective around 170? knots...will have to go back and check that.

DeltaGuy
"The cockpit, what is it?" "It's the little room in the front of the plane where the pilot sits, but that's not importan
 
cdfmxtech
Posts: 1319
Joined: Wed Jul 05, 2000 11:37 am

RE: 777/767 Aileron Question

Wed Jun 16, 2004 1:18 am

Yes, Trailing Edge Flaps.
 
dl757md
Posts: 1482
Joined: Mon May 24, 2004 9:32 am

RE: 777/767 Aileron Question

Wed Jun 16, 2004 3:15 am

As said, they are inhibited by airspeed, I think they become effective around 170?

The AMM only says "lockout occurrs at cruise speeds". Probbly somewhat higher than 170kts.
757 Most beautiful airliner in the sky!
 
cdfmxtech
Posts: 1319
Joined: Wed Jul 05, 2000 11:37 am

RE: 777/767 Aileron Question

Wed Jun 16, 2004 6:21 am

For the B767, the lockout is at around approx 278 kts or Mach .59.

From Maintenance Training Manual
- Outboard Aileron Lockout Schedule
 
AJ
Posts: 2295
Joined: Wed Nov 03, 1999 3:54 pm

RE: 777/767 Aileron Question

Wed Jun 16, 2004 1:01 pm

For the 767 the inboard ailerons droop at flap settings of 5 and above. This can be observed on the control position indicator on the status page.
 
DeltaGuy
Posts: 3965
Joined: Wed Sep 12, 2001 5:25 am

RE: 777/767 Aileron Question

Wed Jun 16, 2004 2:14 pm

Went back and looked at the 767 pubs...

"The aileron lockout control system permits full travel of the outboard ailerons at low speeds and locks out the outboard ailerons at high speeds. This provides the required roll authority at low airspeeds and prevents over controlling at high airspeeds."

There are six spoiler panels located on the upper wing surface of each wing. Spoilers on opposing wings are symmetrically paired. Spoiler panels are used as speedbrakes to increase drag and reduce lift, both in flight and on the ground. The spoilers also supplement roll control in response to control wheel commands.

I said 170-ish knots because I usually only see them really in use when the aircraft is slowed down, i.e. with flaps out...like Dl757 said, the texts doesnt specify an actual airspeed. When you see them in action, the flaperons/spoilers only have to move a tad bit to get a good roll going.

Hope that helps!

DeltaGuy
"The cockpit, what is it?" "It's the little room in the front of the plane where the pilot sits, but that's not importan
 
worldoftui
Posts: 1054
Joined: Fri Aug 24, 2007 5:18 pm

RE: 777/767 Aileron Question

Wed Jun 16, 2004 5:49 pm

Thanks everyone for the replies. And all in plain english for a "non-tecchie!"

Cheers  Smile

Mark
 
oly720man
Posts: 5740
Joined: Fri May 21, 2004 7:13 am

RE: 777/767 Aileron Question

Thu Jun 17, 2004 10:03 pm

Yes, wings are very flexible. The tip ailerons can generate enough force at high speed so a downwards deflection will bend the wing nose down and the effect of the aileron is cancelled by the twist of the wing or, indeed, reversed.

This is, partially, why the F18, for example, has a large wing twist between root and tip so the tip points downwards. THe angle is reduced in flight simply because the wing lift bends the wing.

Andy
wheat and dairy can screw up your brain

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