This Directive is prompted by the results of an FAA audit of the cargo door installation which revealed that a revision to the STC allowed for as many as three cargo door latch lockpins to be inoperative during flight. The actions specified in this AD are intended to prevent an inadvertent in-flight opening of the main deck cargo door, with resultant major structural damage and possible reduced controllability of the aircraft. The effective date required by the FAA is extended approximately two months.