Capt.Fantastic
Topic Author
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767 Floating Aileron

Mon Sep 06, 2004 1:49 am

Here is a shot of a 767-200's wing while in flight from MIA to ATL - I noticed that the inboard aileron was floating up just very slightly during our cruise. Why is that?


src="http://us.f1.yahoofs.com/groups/g_7548763/__hr_B767200+aileron.jpg>

I zoomed in and got this shot - Can anyone tell me what I am seeing here?

src="http://us.f1.yahoofs.com/groups/g_7548763/B767-200+aileron+close-up.jpg>"

 
Capt.Fantastic
Topic Author
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RE: 767 Floating Aileron

Mon Sep 06, 2004 1:50 am

sorry .... the pic did not attach .. Ill try again.
 
KDTWflyer
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RE: 767 Floating Aileron

Mon Sep 06, 2004 3:30 am

I would guess its because the 767 is experiencing a crosswind component at altitude and that particular aileron is being deflected continuously to compensate for that crosswind.
NW B744 B742 B753 B752 A333 A332 A320 A319 DC10 DC9 ARJ CRJ S340
 
SlamClick
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RE: 767 Floating Aileron

Mon Sep 06, 2004 4:19 am

It is not uncommon for planes with a few hours on them, and a few heavy checks and hard landings etc. behind them to be slightly out of rig. I was once non-revving on an old 737 and noticed, moving back and forth across the aisle, that both ailerons were up slightly, and one just a fraction of an inch higher than the other. There was no spoiler float going on at the moment.

After the flight I asked the captain about it. He was surprised to learn about the aileron neutral setting but said that that particular airframe had to be trimmed up manually at cruise. He had to punch off the autopilot, then trim the rudder, then the ailerons, then could put the a/p back on and it would fly with the ball in the middle. Without doing this it would not.

This was one of the early 737s that had the spirit level mounted above the ADI in addition to the "ball" beneath it. They had been using both of these instruments in trimming.

I would assume that in a D-check or the like, that the flight control rig settings would be put back to factory specs. Maybe I am wrong about this. But anyway, if they were, and if the plane had a slight wing or tail bend as a result of turbulence or something, then the factory settings might not make it fly straight and true.

I believe that this may, in part, account for the difference in cruise efficiency seen between older examples of the same type.

Happiness is not seeing another trite Ste. Maarten photo all week long.
 
FredT
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RE: 767 Floating Aileron

Mon Sep 06, 2004 6:17 am

Crosswind doesn't matter except for navigational purposes, as long as you're not trying to land or take off. You simply point your aircraft into the wind until you are going in the intended direction over the ground - without going sideways in any way. It does make sense when you think about it.  Big grin

And I'll chime in with SlamClick. There are many beat-up airframes out there...

Regards,
Fred
I thought I was doing good trying to avoid those airport hotels... and look at me now.
 
rendezvous
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RE: 767 Floating Aileron

Mon Sep 06, 2004 6:35 am

I was preflighting one of our Cessna 172s last week, I noticed that with the controls centred that the left aileron was down about 1cm and the right one about 1/2cm. Our student pilots aren't /that/ rough on the planes are they?  Laugh out loud
 
Yikes!
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RE: 767 Floating Aileron

Mon Sep 06, 2004 7:10 am

Ditto all the above about 30K "smooth" landings and the cumulative effect on airframes and in-flight trim.

Once the outboards are cutout (around 240 KIAS), all control is exercised by the inboards. If it takes a constant deflection of either or both to maintain direction, then that is what the autopilot commands. Sometimes, BOTH inboards are deflected, and sometimes in the same direction!

That, I haven't been able to figure out....

Yikes!
 
FredT
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RE: 767 Floating Aileron

Mon Sep 06, 2004 7:04 pm

Yikes,
yikes!

Sorry. I always wanted to say that.  Smile

What type are you talking about there?

In the pointy-nose world, lots of research has gone into creating FBW systems which will reconfigure their own control laws to cope with severe damage and/or loss of control surfaces. Very interesting, but tends to dive into depths of adaptive neural networks theory and other fields of black magic that I do not wish to explore already in the abstracts. Big grin

Regards,
Fred
I thought I was doing good trying to avoid those airport hotels... and look at me now.
 
Capt.Fantastic
Topic Author
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RE: 767 Floating Aileron

Wed Sep 08, 2004 12:51 pm

Here are the pics:



Here's the close-up of the inboard aileron

 
Capt.Fantastic
Topic Author
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RE: 767 Floating Aileron

Wed Sep 08, 2004 12:53 pm

In the close-up, you can clearly see what I mean by the aileron floating up just slightly
 
Yikes!
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RE: 767 Floating Aileron

Fri Sep 10, 2004 6:41 am

Sorry for the delay - B767

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