what was DC-10's problem?
At the center of the controversy was a serious defect in the McDonnell Douglas DC-10 aircraft. The fault lay not in its performance or handling, but something far more mundane, namely the locking mechanism of its rear cargo door. Previously, most jetliner doors had been of the `plug` type, opening inwards and held firmly inplace by cabin pressure while the aircraft was in flight. But the door on the DC-10, which was built by the Convair division of General Dynamics, opened outwards.Due to the constant force being the exerted against the door while operating at high altitudes, a durable and foolproof locking system was an absolute necessity. The door was designed to be closed with a switch. An electrically powered actuator was used to turn a torque tube to which four latches were attached. As the tube revolved during the locking process, the talon of each latch snapped over a corresponding spool. An external lever was then pulled down, driving a locking pin into place on the outside of each latch. Any jamming of the lever should have been an immediate indication that the latches were not in the correct over-centre position.