On June 11, 1997, a Bell UH-1B (registration N888SJ) was involved in an aviation accident near Heron, CA. Investigators recorded the probable cause as: partial loss of engine power for undetermined reasons. A factor relating to the accident was that the engine lost power when the helicopter was outside (below) the limits of the height/velocity curve. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter performing aerial spraying over a tomato field suffered a partial loss of engine power at low altitude, leading to a hard landing and tail boom separation.
Incident Overview
During an agricultural spraying operation over a tomato field, the pilot of a helicopter encountered a partial loss of engine power while at a low elevation above ground level. In response, the pilot initiated an autorotative landing to manage the descent.
Hard Landing and Tail Boom Separation
The helicopter touched down hard on the field. During the landing sequence, a main rotor blade struck and severed the tail boom. The engine continued to operate for an additional 10 to 12 minutes following the landing.
Post-Accident Examination
Wreckage examination was limited due to the extent of fire damage that occurred. Investigators were unable to determine the reason for the partial loss of engine power.
Conclusion
The investigation concluded that the cause of the power loss could not be identified due to the fire damage and limited evidence available.