Incident Overview
A helicopter attempted a pinnacle takeoff from a grassy knoll. During the takeoff, the pilot encountered a condition where engine RPM and main rotor RPM decreased together—a low rotor RPM condition. The pilot reported lowering the collective in an effort to recover, but was unable to restore main rotor RPM quickly enough to avoid a forced landing.
Forced Landing and Rotor Strike
The helicopter executed a run-on landing in a grassy area. During the landing, the main rotor blades and tail rotor blades contacted the ground, resulting in damage.
Passenger Injury
After the helicopter came to rest, a passenger exited the aircraft while the main rotor was still turning. The passenger was struck in the head by a rotor blade.
Technical Reference
According to the FAA Basic Helicopter Handbook, a low rotor RPM condition can be corrected by reducing collective pitch, which decreases rotor drag and allows rotor RPM to increase. However, the helicopter manufacturer notes that once RPM drops below the normal operating range, it may take several seconds for the RPM to recover to the normal range.