What happened
On August 11, 2008, at approximately 15:30 CDT, a Bell 20ral 206L-1 helicopter, N832AH, experienced a partial loss of engine power while performing external load operations near Heber Springs, Arkansas. The aircraft was transporting an empty container on a long line at 300 feet above ground level when the engine began to spool down.
The pilot, who was the sole occupant, released the external load and performed a 180-degree turn to execute an autorotation. During the forced landing, the helicopter struck trees in a tree farm and landed with significant force, causing the aircraft to roll onto its right side. The pilot was not injured.
The investigation
An examination of the Rolls Royce 250-C30P engine revealed that a PC line B-nut had become disconnected. Maintenance records indicated that the last time this specific PC line had been removed and reinstalled was 67.1 flight hours earlier during a scheduled turbine change. Investigators noted that no torque paint (slippage marks) was present on the fitting to indicate the connection had been properly secured.
Findings
- The engine's PC line B-nut was found disconnected.
- No slippage marks were present on the fitting.
- The aircraft encountered trees during the forced landing procedure.