On August 27, 1998, an Aerospatiale SA316B (registration N605RA) operated by U.s. Dept. OF The Interior was involved in an aviation accident near Porterville, CA. Investigators recorded the probable cause as: The pilot's failure to maintain adequate in-flight clearance between the bucket and trees resulting in the entanglement/separation of the long line and subsequent impact with and separation of the tail rotor assembly. A factor was the trees. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 2 related events involving the same aircraft type or operator are linked below.
A helicopter's bambi bucket line became entangled in trees, snapped, and wrapped around the tail rotor, causing the tail rotor blades and gearbox to separate. The helicopter spun to the ground and rolled down a steep slope.
Accident Overview
A helicopter equipped with a bambi bucket attached to a 100-foot-long line was involved in an accident when the bucket became entangled in trees. The line subsequently snapped and wrapped itself around the tail rotor, leading to the separation of the tail rotor blades and gearbox from the aircraft. The helicopter then spun to the ground and rolled down a steep slope.
Pilot Report
According to the pilot, there was no mechanical malfunction with the aircraft prior to the accident. This suggests that the event was triggered solely by the external entanglement.
Physical Evidence
Investigation of the wreckage revealed wire marks on the tail rotor blades and around the output shaft, consistent with the line having wrapped around those components. No other anomalies were reported.