Eurocopter EC130 N11QP accident near Hilo, Hawaii

Probable cause

The separation of the left sliding door in flight after it opened for reasons that could not be determined based on the available evidence, which resulted in damage to the main rotor blades.

NTSB analysis

The pilot reported that, before departing, he conducted a walk-around inspection of the helicopter, during which he visually checked to ensure all the doors and cowlings were closed and secured. The pilot departed on the flight with the maintenance apprentice, who was seated in the right front seat. While the flight was en route back to the airport, the left-rear sliding door suddenly slid open, separated from the helicopter, and struck two of the three main rotor blades. The pilot performed a precautionary landing to a field. The helicopter sustained substantial damage to two main rotor blades. The helicopter’s left sliding door tracks and door latch assemblies were normal and unremarkable. The plastic latch on the fuselage which supports the sliding rear door when opened was damaged, and a portion had separated from the fuselage. The sliding door fell into the ocean and was not recovered, thereby preventing examination of the door and its locking components.

After the accident, Airbus Helicopters published an alert service bulletin requiring a mandatory spring-scale check on all sliding door-equipped EC-130 B4 helicopters to ensure correct operation of the sliding door locking system.

Text from the NTSB. Open the NTSB docket for WPR18TA239 for the full record.