Bell 206L-1 N832AH accident near Heber Springs, Arkansas

Probable cause

the improper installation of the PC line on the engine which resulted in a partial loss of engine power. Contributing to the accident was the trees encountered during the forced landing.

NTSB analysis

The helicopter had been conducting external load operations on the day of the accident and had just departed after refueling. While transporting an empty container on the long line at 300 feet above ground level, the engine "spooled down". The pilot released the external load, executed a 180-degree turn and autorotation. During the forced landing, the helicopter landed hard in a tree farm and impacted trees, rolled over and came to rest on its right side. The pilot shut off the fuel and exited the helicopter. Examination of the engine showed the PC line B-nut was found disconnected. The last engine maintenance which involved the removal and reinstallation of the PC line was 67.1 hours prior, during a scheduled turbine change. No slippage marks (torque paint) were noted on the fitting. The engine manufacturer's maintenance manual procedures document the proper installation procedures, which include slippage markings.

Text from the NTSB. Open the NTSB docket for DEN08LA138 for the full record.