Originally Posted by
megan
The trouble with the DC-10 at Chicago was that it relied on hydraulic pressure to keep the leading edge devices deployed, once the hydraulics lost pressure due damage incurred they retracted. It was said it wouldn't happen on a Boeing as the devices are mechanically latched (I don't know if that is indeed a fact, but was a reason given at the time). If that is indeed the case I'd assume damage would be limited to those devices impacted by debris and the loss of lift being minimal.
That's correct, although not via mechanical latches. On Puget Sound Boeings, the flaps/slats are moved via jack screws - not by direct hydraulic pressure as was the case on the DC-10. Jack screws can't really be back-driven, so loss of hydraulics means they'll stay where they are.