Originally Posted by cmd320

AA191 also highlighted issues with the DC-10's design though. Because all hydraulic lines powering the slats were routed through the front of the wing, they were damaged upon separation of the engine causing the slats on the left wing to retract and thus causing that wing to stall. The loss of the engine was not actually much of an issue, it was the damage it caused to the wing on its way off that triggered the accident chain.

After the investigation it was found that Douglas routed the hydraulic lines similar to how they had on the DC-9 which we all know does not have wing-mounted engines. Had a redundant line been placed on the trailing side of the wing on the DC-10, the slats could have stayed locked in place and the aircraft would have remained controllable.