lmml 14/32
Posts: 2358
Joined: Tue Jan 30, 2001 2:27 am

DC-10: The Relation Between Ailerons And Gear

Thu Nov 14, 2002 11:23 pm

Below is a quotation from Capt Haynes (of the Sioux City DC-10 crash):

"There are two ways we can get the gear down on the DC-10 with
hydraulic failure. You can put the gear handle down, which manually
unlocks the doors and the doors fall open and the gear just falls out,
because it's been resting on the doors. Or, there's an alternate
method of doing that, when you use no flaps. Because we have four
ailerons on the DC- 10. You fly with the inboard ailerons at high
speed, and then you unlock the outboard ailerons for landing when you
lower the flaps. Well, we didn't have any flaps. So we couldn't
unlock the outboard ailerons. So that's what this alternate gear
method is for. And we talked about this: how do we put the gear down,
and it was suggested, we unlock with the outboard ailerons, with the
alternate gear
, because there might be something out there, because we
might be able to get some fluid out there, there might be some trapped
out there. "


Can anybody please explain the bold type?
 
cdfmxtech
Posts: 1319
Joined: Wed Jul 05, 2000 11:37 am

RE: DC-10: The Relation Between Ailerons And Gear

Fri Nov 15, 2002 12:24 am

On the DC10, when you use the alternate gear extension lever, the outboard ailerons are unlocked (if they aren't already unlocked).
 
FDXmech
Posts: 3219
Joined: Sun Mar 19, 2000 9:48 pm

RE: DC-10: The Relation Between Ailerons And Gear

Fri Nov 15, 2002 12:47 am

On the DC10, the outboard ailerons are normally "unlocked when the slats and or flaps are extended.

But there is another means of to unlock the outboard ailerons, and that is by extending the landing gear manually. Manual gear extension in DC10 lingo is alternate extension and is achieved using the alternate extend handle.

Without a means of lowering the flaps/slats, pulling the alternate gear extend handle will unlock the outboard ailerons (as well as drop the gear).

Interestingly the mechanism to unlock the o/b aileron uses a flap input or slat input or alternate gear handle input and so is called the "or mechanism"...really.
You're only as good as your last departure.
 
lmml 14/32
Posts: 2358
Joined: Tue Jan 30, 2001 2:27 am

RE: DC-10: The Relation Between Ailerons And Gear

Fri Nov 15, 2002 1:37 am

Following the events of that miraculous crash this may sound extremely stupid.

Why didn't the crew extend the gear earlier during their eventful descent if they thought this would give them some aileron?
 
zionstrat
Posts: 225
Joined: Sat Apr 28, 2001 3:26 am

RE: DC-10: The Relation Between Ailerons And Gear

Fri Nov 15, 2002 2:01 am

It's been a long time since I studied this one, but I think the outer aileron comment was more of a shot in the dark than a rational option. If I remember correctly, with all hydraulic systems severed there was not enough pressure to have any effect.

Of course they were dealing with a completely unexpected situation as no one thought all 3 systems could go at once, so I can't second guess them for hoping that anything might work.
 
ERFly
Posts: 162
Joined: Thu Aug 22, 2002 12:47 pm

RE: DC-10: The Relation Between Ailerons And Gear

Fri Nov 15, 2002 4:20 am

Zionstrat is right. They were test pilots up there. They didn't know if anything was going to work. They were just using all of their options.

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