On July 26, 1997, a Bell 47G-3B-1 (registration N35134) was involved in an aviation accident near Mt. Vernon, OH. Investigators recorded the probable cause as: The pilot's failure to maintain rotor RPM. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter conducting 5-minute sightseeing tours experienced an unexplained RPM loss at 75 feet AGL. The pilot turned back, but rotor RPM further decayed with a tailwind, leading to a hard impact that severed the tail boom. No mechanical issues were found.
Incident Details
A helicopter engaged in short sightseeing flights departed with two passengers. Approximately 75 feet above ground level, the pilot reported an unexplained loss of engine RPM. The pilot immediately reversed course using right pedal input to return to the departure point.
Pilot Actions
During the turn, while maneuvering to avoid obstacles and operating with a tailwind, the pilot noted that rotor RPM continued to decay. The helicopter subsequently impacted the ground hard, and the main rotor blade severed the tail boom during the impact sequence.
Post-Accident Examination
The pilot reported no mechanical problems prior to the event. Investigators found no fuel contamination. A Federal Aviation Administration inspector started the engine twice without detecting any mechanical malfunctions.