b773
Posts: 58
Joined: Sat Jan 27, 2001 7:48 am

Tale Fin Moved To The Left?

Sat Oct 04, 2003 5:21 am

Why do sometimes when planes are parked, they move the back part of the tail to the left?

 
UAL747
Posts: 6725
Joined: Mon Dec 13, 1999 5:42 am

RE: Tale Fin Moved To The Left?

Sat Oct 04, 2003 5:39 am

It's probably moved in a certain direction because of the wind. At DFW, walk by the line up of 777's at the gate, and all of their rudders will be turned to the left because of a wind coming from the South.

UAL747
"Bangkok Tower, United 890 Heavy. Bangkok Tower, United 890 Heavy.....Okay, fine, we'll just turn 190 and Visual Our Way
 
bio15
Posts: 1048
Joined: Fri Mar 23, 2001 8:10 am

RE: Tale Fin Moved To The Left?

Sat Oct 04, 2003 9:53 am

I would guess it has something to do with hydraulics and the actuators on the rudder fin. Probably it's because the APU powers some system and not the other. I have seen A300's sitting on the gate with only the right low-speed aileron drooped all the way down, and the other horizontal. It is just a guess, someone please correct me if I'm misataken

-Alfredo
 
AJ
Posts: 2295
Joined: Wed Nov 03, 1999 3:54 pm

RE: Tale Fin Moved To The Left?

Sat Oct 04, 2003 12:17 pm

Pretty close, it is because the hydraulics are not pressurised, allowing gravity and wind to affect the control surfaces. The outboard ailerons on a Boeing remain level as they are mass balanced.
 
dc10hound
Posts: 460
Joined: Fri Dec 15, 2000 4:18 pm

RE: Tale Fin Moved To The Left?

Sat Oct 04, 2003 12:39 pm

Probably it's because the APU powers some system and not the other. I have seen A300's sitting on the gate with only the right low-speed aileron drooped all the way down, and the other horizontal.

If any of the A300-600's three hydraulic systems are powered, both left and right All Speed Ailerons should be (Better be...) neutral (horizontal)....
"Eagles soar. But weasels never get sucked into jet intakes.."
 
bio15
Posts: 1048
Joined: Fri Mar 23, 2001 8:10 am

RE: Tale Fin Moved To The Left?

Sun Oct 05, 2003 2:31 am

I couldn't find a picture of an A300 with only the right aileron hanging down, here's two with both hanging down:


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Photo © Orlando Beaumont
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Photo © Darcy Stevens



DC10hound,
It sounds pretty logical to me that all equal control surfaces on each side should be powered by the same systems. It would mean less risk in the event of one system failure, right?

AJ,
If the systems were not pressurized on the A300's I saw, what is a probable cause that the left aileron remained straightened horizontally?

Thanks in advance
-Alfredo
 
flyingbronco05
Posts: 3484
Joined: Fri May 10, 2002 11:43 am

RE: Tale Fin Moved To The Left?

Mon Oct 06, 2003 1:59 am

they move the back part of the tail to the left?

It's called the rudder and or rudder tab/trim.

FB05
Never Trust Your Fuel Gauge
 
AJ
Posts: 2295
Joined: Wed Nov 03, 1999 3:54 pm

RE: Tale Fin Moved To The Left?

Mon Oct 06, 2003 8:24 am

Alfredo, the time for the surfaces to droop depends on a few factors, retention of hydraulic pressure in well sealed lines, wind or other external pressures etc.

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