What happened
A student pilot was performing his third supervised solo flight, having already completed two successful takeoffs and landings. During the third landing attempt, the helicopter made contact with the ground, at which point it began to vibrate violently. The student pilot was unable to arrest the vibration before the aircraft began to break apart.
The accident was witnessed by the student pilot's flight instructor. Using a hand-held radio, the instructor instructed the student to pick up the helicopter to attempt a recovery.
The investigation
An examination of the landing skid dampers revealed that they were improperly charged. At the time of the accident, the aircraft had been operated for 371 hours since its most recent annual inspection, which had occurred approximately six months prior. Additionally, the aircraft had been operated for 85 hours since its most recent 100-hour inspection. The student pilot had a total of 22 hours of flight experience, all conducted in the same make and model as the involved aircraft.