LHSebi
Topic Author
Posts: 1007
Joined: Wed Jan 07, 2004 4:24 am

No Hydraulics = Elevators Up?

Thu Apr 29, 2004 8:46 am

Hello,
I was just browsing through the photos, and saw the following picture:

View Large View Medium
Click here for bigger photo!

Photo © Wietse de Graaf - AirTeamImages



I think it's a great shot, but if the hydraulics are offline, shouldnt the elevators hang down because of their weight?

Any help appreciated!

Sebastian
I guess that's what happens in the end, you start thinking about the beginning.
 
L-188
Posts: 29874
Joined: Wed Jul 07, 1999 11:27 am

RE: No Hydraulics = Elevators Up?

Thu Apr 29, 2004 8:58 am

Actually they shouldn't hang up or down at all if they are balenced and there isn't any wind effecting them.
OBAMA-WORST PRESIDENT EVER....Even SKOORB would be better.
 
DC-10Tech
Posts: 291
Joined: Fri Jun 15, 2001 6:40 pm

RE: No Hydraulics = Elevators Up?

Thu Apr 29, 2004 3:18 pm

It really depends on how the wind blows, really. As L-188 said, they're balanced, so in theory, they won't move at all with no hydro pressure.
Forums.AMTCentral.com
 
LHSebi
Topic Author
Posts: 1007
Joined: Wed Jan 07, 2004 4:24 am

RE: No Hydraulics = Elevators Up?

Thu Apr 29, 2004 6:25 pm

Ok, but can anyone explain the photo then?

Sebastian
I guess that's what happens in the end, you start thinking about the beginning.
 
DeskPilot
Posts: 704
Joined: Wed Apr 07, 2004 8:02 am

RE: No Hydraulics = Elevators Up?

Thu Apr 29, 2004 7:53 pm

Is there a control lock ?
By the way, is there anyone on board who knows how to fly a plane?
 
AUAE
Posts: 292
Joined: Fri Apr 09, 2004 4:41 am

RE: No Hydraulics = Elevators Up?

Thu Apr 29, 2004 9:02 pm

Interesting picture. It is normal for control surfaces to droop when hydraulic pressure is off. Control surfaces are balanced, but usually never dead nuts so to speak. For instance, MD11 elevators are balanced tail heavy. It could be a case where the elevator shown is balanced nose heavy, but I wouldn't think that is the case. Maybe they just have the elevator locked in an up position for MTC?

Shawn
Air transport is just a glorified bus operation. -Michael O'Leary, Ryanair's chief executive
 
AAR90
Posts: 3140
Joined: Fri Jan 21, 2000 11:51 am

RE: No Hydraulics = Elevators Up?

Thu Apr 29, 2004 11:12 pm

Maybe they just have the elevator locked in an up position for MTC?


Or wind. Shut off hydraulics on the B738 and just a little tailwind will cause the yoke to move full aft (nose up) within seconds.
*NO CARRIER* -- A Naval Aviator's worst nightmare!
 
LHSebi
Topic Author
Posts: 1007
Joined: Wed Jan 07, 2004 4:24 am

RE: No Hydraulics = Elevators Up?

Fri Apr 30, 2004 2:54 am

Well, perhaps Wietse can give us some help here as noone knows for sure?

Sebastian
I guess that's what happens in the end, you start thinking about the beginning.
 
DC-10Tech
Posts: 291
Joined: Fri Jun 15, 2001 6:40 pm

RE: No Hydraulics = Elevators Up?

Fri Apr 30, 2004 3:09 pm

The question has already been answered. With no hydro on, the elevators will go where ever the wind blows them! Its not uncommon to see all of them down, all of them up, one down, one up, you name it, it really just depends!
Forums.AMTCentral.com
 
wietse
Posts: 3630
Joined: Thu Oct 18, 2001 12:49 am

RE: No Hydraulics = Elevators Up?

Mon May 03, 2004 6:21 pm

Hey,

I really dont know what the general question is here, but I cant imagine there to be any hydrolic pressure in this photo. The engines are removed and the plane is not connected to an external generator or pump. And if you look closely at the gearbay doors, you will see that they are hanging from their sockets.

I dont have any inside information on the status of this plane, and the photo was not shot from airside terrain.

Wietse
Wietse de Graaf
 
VC-10
Posts: 3546
Joined: Tue Oct 26, 1999 11:34 am

RE: No Hydraulics = Elevators Up?

Mon May 03, 2004 9:23 pm

With an a/c in that state I would imagine all the PCU's have been removed.

I'm suprised no-one has noticed both hi-speed ailerons are down and the RH Lo-speed aileron is up as well. The position of these controls wil depend on how they are balanced and what influence the wind has.

The postion of the LG doors means nothing as thay may have been dropped by maintenance.
 
LHSebi
Topic Author
Posts: 1007
Joined: Wed Jan 07, 2004 4:24 am

RE: No Hydraulics = Elevators Up?

Tue May 04, 2004 7:57 am

VC-10,
Thanks for your reply. Could you please clarify for the less knowledgeable what a PCU is? Thanks!

Sebastian
I guess that's what happens in the end, you start thinking about the beginning.
 
VC-10
Posts: 3546
Joined: Tue Oct 26, 1999 11:34 am

RE: No Hydraulics = Elevators Up?

Tue May 04, 2004 8:20 am

PCU = Power Control Unit - The hydraulic actuator that control the position of the flight control, and also damps it when the hydraulics are off and the wind moves the surfaces.

They are also known as PF(flying)CU's & servo's.

Who is online

Users browsing this forum: ATA L1011, Baidu [Spider], sunrisevalley and 16 guests