Mcdonnels DC-10

The model dc10’s troubles begins in the 1970s, which gave it an unfavorable reputation. In fact, the DC-10's lifetime safety record as of 2003 made the DC-10 among the safest aircraft for passenger travel except a few problems.
Cargo Door
The DC-10 was designed with cargo doors that opened outward instead of inward as inward-opening doors used on smaller pressurized aircraft. Outward-opening doors allowed larger openings required by baggage for a wide-body jet. Outward-opening doors rely on a heavy locking mechanism to secure the door against the outward force caused by the pressurization of the fuselage. In the event that the door lock breakdown, there was potential for explosive decompression. This was discovered in 1972 following an incident aboard American Airlines Flight 96, but until the Turkish Airlines Flight 981 crash in 1974 there was no repair orders. This was just a one problem of the plane.
The other design problem was locking flap mechanisms designed to keep their position in the event of a hydraulic failure. The all three hydraulic systems were located too close to each other, directly beneath the tail engine.
Engine pylons
Although the design of the engine pylons was suitable, it was not designed to make a easy maintenance.The standart procedure of changing the engines was to detach the engine from the pylon first but McDonnell-Douglas advised against this procedure and it caused the crash of American Airlines Flight 191.Because of this American Airlines fined with $500,000.