What happened
The aircraft experienced a separation of the right wing number three leading edge slat while descending for an approach.
The investigation
An investigation revealed that on July 5, 1984, the company performed a 'C' check inspection of the aircraft. At this time, a right wing number three leading edge slat retract aluminum pulley, part number 1969-132, was replaced with a phenolic pulley, part number 1969-172. The DC-10 Parts Illustrated Catalogue specifies that an aluminum pulley be installed on the number three leading edge slat rather than the phenolic pulley because flight loads on the number three slat exceeded the design load of the phenolic pulley. Metallurgical examination of the failed pulley and cable indicated evidence of an overload failure. Inspection of other company DC-10s revealed at least 3 other aircraft had phenolic pulleys installed in the number three slat position.