Primary finding
Probable cause
A loss of engine power for reasons that could not be determined due to a lack of available evidence.
Investigator assessment
Analysis narrative
The pilot was conducting a night cross country flight in his single-engine helicopter to evaluate the progress of some construction projects. As he approached the landing area, he noticed some loose construction debris, so he flew past the site and turned around to approach from the opposite direction. Shortly thereafter, the engine began losing power. Unable to maintain level flight he conducted an emergency landing to a river. By the time he was rescued, about 11 hours after the accident, the helicopter had sunk and was not located despite an extensive search by local law enforcement. Given that the wreckage was not recovered, an examination of the engine to determine a reason for the loss of power could not be performed.