Eurocopter France EC 130 B4 N133HN accident near Shoals, West Virginia

Probable cause

The improper locking of the rear passenger door by the specialty nurse, which resulted in the door separating from the helicopter in flight.

NTSB analysis

Before takeoff for the positioning flight, the specialty nurse slid closed and latched the left rear door. About 5 minutes after departure, while the helicopter was in cruise flight, the left rear door opened and then separated from the helicopter. The pilot diverted the helicopter to a nearby airport and landed uneventfully. The door was recovered, and postaccident examination revealed that the damage to the door and the airframe was consistent with the damage having incurred during the door's separation from the helicopter. Postaccident examination did not reveal any evidence of preexisting damage of the door frame, door, or door's locking mechanism that would have precluded normal operation. It is likely that the specialty nurse locked the door incorrectly, which resulted in an inadvertent in-flight door opening as the helicopter was traveling 55 knots faster than the manufacturer's specified never-to-exceed speed for operating with the door open, and subsequent separation of the door from the helicopter.

Text from the NTSB. Open the NTSB docket for ERA16LA098 for the full record.