Originally Posted by
flash8
Does the DC-10/MD-11 autopilot utilize the cabin floor routed control cables to operate the (tail) control surfaces? Or was it a different system, possibly above the cabin using electrical signals? I would usually look at the manual but I can't find any online in pdf format to fathom the answer to this question, which to fellow oldies/anoraks will know why I am asking.
I'd have to dig out the MD-11 schematics to be certain but my recollection is that, unless LSAS (Longitudinal Stability Augmentation System) is shut down or failed, the elevators are controlled by electrical signals from the Flight Control Computers (FCC) to the elevator hydraulic rams. This would be the case whether AP is engaged on not. When AP is off, manual column force is sensed by the Control Wheel Steering sensors in the control wheel hubs. Feedback from the rams to the control column is by the mechanical cables which become primary if LSAS/CWS/AP becomes inoperative.
I didn't work on DC-10 but I assume its CWS worked in a similar way. (But no, I don't know why you are asking.)