Accident Summary
A helicopter accident occurred during a flight instruction session when the pilot receiving instruction attempted a run-on landing on a grassy area between the runway and taxiway. The flight instructor reported that the helicopter touched down at about 25 miles per hour, and the pilot then lowered the collective to the full down position while the helicopter still had considerable forward momentum. This caused the helicopter to lurch forward and the nose to lower.
Sequence of Events
The flight instructor stated that as the helicopter began to pitch forward, he took control and applied aft cyclic to prevent the main rotor blades from striking the ground. However, the rotor blades impacted and separated the tailboom. The fuselage continued forward, the nose struck the ground, and then the helicopter settled back onto its skids. The helicopter sustained substantial damage to the fuselage, main rotor system, tailboom, and tail rotor system.
Contributing Factors
The flight instructor reported no preimpact mechanical failures or malfunctions with the airframe or engine. He noted that the pilot had successfully performed run-on landings on the same sod area in the past. The instructor recommended landing on the sod to reduce wear on the skid shoes from the paved runway.
Training Guidance
The Enstrom Helicopter Corporation's Training Maneuvers Manual (2014) includes a caution that Enstrom does not endorse practicing run-on landings. It advises that run-on landings should be conducted on a smooth, hard surface and planned to the center of the runway to prevent sliding or overturning. The manual also states that after ground contact, the collective position should be maintained and directional control ensured until the helicopter stops.
The FAA Helicopter Instructor's Handbook (FAA-H-8083-4, 2012) advises against rapidly lowering the collective after touchdown, as this can cause a rapid stop and potential damage or injury. It also notes that for skid-equipped helicopters, hard-surface runways may be preferable to grassy fields to reduce the risk of catching a skid and dynamic rollover.
Safety Recommendations
The flight instructor suggested that landing on the runway instead of the sod might have reduced the effects of the improper collective application. He also noted that he should have verbally reviewed the importance of collective usage for friction control during the traffic pattern and should have maintained a guarded position on the flight controls to decrease reaction time.