Piper PA-31T N39EH accident near Cheyenne, Wyoming

Probable cause

The flight crew’s failure to properly latch the cabin door before takeoff.

NTSB analysis

The airplane was climbing through 7,500 feet when the main cabin door opened in-flight and subsequently separated from the airframe. The main cabin door was later recovered and examined. The examination revealed deformation on the outer skin on the lower end of the door; the skin deformation was consistent with the door rotating downward and aft relative to the hinge attachment. The fracture surfaces were on slant planes consistent with ductile overstress fracture. No evidence of preexisting cracks was observed. The door latching mechanism was examined and all pushrods, latch pins, and the associated bellcrank were in place and intact. Wear was observed on the upper side of the forward pins at the middle and upper positions; however, the latching mechanism travel and extension of the latch pins was correct. No other anomalies were noted; thus it is likely the door latch mechanism was not fully engaged before takeoff, which resulted in the door opening in-flight.

Text from the NTSB. Open the NTSB docket for WPR12LA030 for the full record.