LMML 14/32 From Malta, joined Jan 2001, 2565 posts, RR: 6 Posted (11 years 11 months 1 week 6 days 6 hours ago) and read 2700 times:
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. "
FDXmech From United States of America, joined Mar 2000, 3251 posts, RR: 34
Reply 2, posted (11 years 11 months 1 week 6 days 4 hours ago) and read 2651 times:
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.
Zionstrat From United States of America, joined Apr 2001, 226 posts, RR: 0
Reply 4, posted (11 years 11 months 1 week 6 days 3 hours ago) and read 2624 times:
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.