Incident Details
A certified flight instructor was providing instruction to a private-rated dual student during simulated forced landings. The training involved a practice autorotation. As part of the recovery procedure, the throttle was advanced to the full position, but the engine did not regain rotor RPM, necessitating a forced landing. During the touchdown, the helicopter nosed over, and the main rotor struck the terrain.
Post-Incident Examination
A post-accident engine run was conducted under test cell conditions. During this test, the engine produced full rated power. An inspection of the engine was also performed. The inspection did not reveal any evidence that could explain the reported failure of the engine to respond during the accident sequence. No determination regarding the cause of the engine's lack of response was made.