On September 3, 1989, a Bell 47G-2 (registration N37870) operated by Martinez,juan was involved in an aviation accident near Cayey, PR. Investigators recorded the probable cause as: LOSS OF ENGINE POWER FOR AN UNKNOWN REASON. A FACTOR RELATED TO THE ACCIDENT WAS: THE PRESENCE OF TREES IN THE EMERGENCY LANDING AREA. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A private pilot training for a helicopter rating experienced a rotor RPM drop and loss of power response, leading to a forced landing in trees. No cause was found for the power loss.
Incident Overview
A private pilot holding a single-engine land rating and undergoing training for a helicopter rating was on a local flight when he encountered a decrease in rotor RPM at approximately 300 feet above ground level. The pilot reported attempting to restore rotor speed by advancing the throttle, but there was no response from the engine.
Emergency Landing
Unable to reach a clearing, the pilot performed a forced landing in trees. The helicopter came to rest in the wooded area. No further details about the aircraft or the pilot's condition were provided.
Investigation Findings
An investigation into the incident found no reason for the reported loss of power. The exact cause of the rotor RPM drop and subsequent lack of throttle response could not be determined.
Pilot Background
The pilot was in the process of earning a helicopter rating, having previously held only a fixed-wing private pilot certificate. The flight was part of his training curriculum.