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No Hydraulics = Elevators Up?  
User currently offlineLHSebi From Germany, joined Jan 2004, 1049 posts, RR: 8
Posted (10 years 3 months 3 days 16 hours ago) and read 1840 times:

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

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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.
12 replies: All unread, jump to last
 
User currently offlineL-188 From United States of America, joined Jul 1999, 29791 posts, RR: 58
Reply 1, posted (10 years 3 months 3 days 16 hours ago) and read 1812 times:

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.
User currently offlineDC-10Tech From United States of America, joined Jun 2001, 298 posts, RR: 2
Reply 2, posted (10 years 3 months 3 days 9 hours ago) and read 1697 times:

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
User currently offlineLHSebi From Germany, joined Jan 2004, 1049 posts, RR: 8
Reply 3, posted (10 years 3 months 3 days 6 hours ago) and read 1670 times:

Ok, but can anyone explain the photo then?

Sebastian



I guess that's what happens in the end, you start thinking about the beginning.
User currently offlineDeskPilot From Australia, joined Apr 2004, 767 posts, RR: 0
Reply 4, posted (10 years 3 months 3 days 5 hours ago) and read 1662 times:

Is there a control lock ?


By the way, is there anyone on board who knows how to fly a plane?
User currently offlineAUAE From United States of America, joined Apr 2004, 296 posts, RR: 3
Reply 5, posted (10 years 3 months 3 days 4 hours ago) and read 1642 times:

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
User currently offlineAAR90 From United States of America, joined Jan 2000, 3466 posts, RR: 47
Reply 6, posted (10 years 3 months 3 days 1 hour ago) and read 1625 times:

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!
User currently offlineLHSebi From Germany, joined Jan 2004, 1049 posts, RR: 8
Reply 7, posted (10 years 3 months 2 days 22 hours ago) and read 1562 times:

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.
User currently offlineDc-10tech From United States of America, joined Jun 2001, 298 posts, RR: 2
Reply 8, posted (10 years 3 months 2 days 9 hours ago) and read 1494 times:

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
User currently offlineWietse From Netherlands, joined Oct 2001, 3809 posts, RR: 55
Reply 9, posted (10 years 2 months 4 weeks 1 day 6 hours ago) and read 1396 times:

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
User currently offlineVC-10 From United Kingdom, joined Oct 1999, 3700 posts, RR: 34
Reply 10, posted (10 years 2 months 4 weeks 1 day 3 hours ago) and read 1376 times:
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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.


User currently offlineLHSebi From Germany, joined Jan 2004, 1049 posts, RR: 8
Reply 11, posted (10 years 2 months 4 weeks 17 hours ago) and read 1331 times:

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.
User currently offlineVC-10 From United Kingdom, joined Oct 1999, 3700 posts, RR: 34
Reply 12, posted (10 years 2 months 4 weeks 16 hours ago) and read 1331 times:
Support Airliners.net - become a First Class Member!

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.


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