On July 26, 2004, a Schweizer 269C (registration N62126) operated by Silverhawk Aviation Llc was involved in an aviation accident near Homedale, ID. Investigators recorded the probable cause as: The loss of engine power for an undetermined reason while maneuvering at low altitude, which resulted in a hard landing. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter conducting corn pollination suffered an engine failure during a turn, leading to loss of rotor RPM and a hard landing that severed the tail boom. Engine examination revealed low compression from carbon deposits, but the cause of power loss remains undetermined.
Incident Overview
A helicopter engaged in corn pollination operations experienced an engine failure while executing a turn to reverse direction. The pilot reported a subsequent loss of main rotor RPM. Despite efforts to increase rotor RPM by lowering the collective and rolling the throttle into the overtravel spring, the pilot was unsuccessful in recovering from the low rotor speed condition.
Hard Landing and Damage
The helicopter made a hard landing, during which the main rotor blades severed the tail boom.
Engine Examination
Initial examination of the engine revealed low compression readings on the cylinders. Partial disassembly showed that the low compression was due to loose carbon deposits found on the seating surface of the valves and seats. The carbon was most likely knocked loose during the impact. No other anomalies were noted during the engine examination, and no signatures or conditions were observed consistent with any pre-mishap mechanical malfunction.
Undetermined Cause
The reason for the loss of engine power was not determined.