St. Louis, IL, USA
N369PA
Guimbal CABRI
The flight instructor reported that, during a training flight in the helicopter, he briefed the student pilot on the procedures required to land with a simulated stuck left pedal. The student began a descent to enter a shallower-than-normal glidepath to the runway surface, and he completed his final checks for the maneuver and continued the approach. During the approach the flight instructor directed the student pilot to use "throttle manipulation to control the yaw caused by a fixed input on the anti-torque system." Upon contacting the runway, the helicopter veered left, and the instructor chose to abort the landing. As the helicopter lifted off, it began to rapidly yaw left while drifting left of the runway. Recognizing that the helicopter was in a spin, they attempted to correct by leveling the helicopter long enough to regain tail rotor authority. The helicopter's left skid impacted mud on the left side of the runway, and the helicopter rolled onto its left side. The helicopter sustained substantial damage to the main rotor, fuselage, and tailboom. The instructor reported that there were no preaccident mechanical failures or malfunctions with the helicopter that would have precluded normal operation. A manufacturer's service letter, SL 19-002 A, stated, "During in-flight tail rotor control failure simulation, pilots should never use the twist grip to control yaw." Therefore, the flight instructor's direction to the student to use the throttle to correct the yaw was incorrect and led to ground impact and a dynamic rollover.
The helicopter flight instructor reported that, during a training flight, he briefed the student pilot on the procedures required to land with a simulated stuck left pedal. The student began a descent to enter a shallower-than-normal glide path to the runway surface, and he completed his final checks for the maneuver and continued the approach. Upon contacting the runway, the helicopter veered to the left, and the instructor elected to abort the landing. As the helicopter lifted off, it began to yaw to the left at a rapid rate, while drifting to the left of the runway. Recognizing the helicopter was in a spin, they attempted to correct by leveling the helicopter "long enough for the aircraft to regain tail-rotor authority." The helicopter's left skid impacted the mud on the left side of the runway and the helicopter rolled onto its left side. The Federal Aviation Administration's Helicopter Flying Handbook, FAA-H-8083-21A, provides information and guidance in a section titled "Landing – Stuck Neutral or Right Pedal" which stated in part: The landing profile for a stuck neutral or a stuck right pedal is a low-power approach terminating with a running or roll-on landing. The approach profile can best be described as a shallow to normal approach angle to arrive approximately 2–3 feet landing gear height above the intended landing area with a minimum airspeed for directional control. During the approach the flight instructor directed the student pilot to "utilize throttle manipulation to control the yaw caused by a fixed input on the anti-torque system." The manufactures service letter, SL 19-002 A, states, "During in-flight tail rotor control failure simulation, pilots should never use the twist grip to control yaw." The helicopter sustained substantial damage to the main rotor, fuselage and tail-boom. The flight instructor reported that there were no preaccident mechanical failures or malfunctions with the helicopter that would have precluded normal operation. The automated weather observation station located on the airport reported that, about the time of the accident, the wind was variable at 4 knots.
The flight instructor's improper emergency procedure instruction to the student pilot, which resulted in the student improperly using the throttle to correct the loss of yaw control, which resulted in ground impact and a dynamic rollover.
Source: NTSB Aviation Accident Database
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