NTSB Identification: LAX04CA097
14 CFR Part 91: General Aviation
Accident occurred Tuesday, January 20, 2004 in Mesa, AZ
Probable Cause Approval Date: 03/30/2004
Aircraft: Eurocopter AS350 B3, registration: N970AE
Injuries: 3 Uninjured.

NTSB investigators used data provided by various entities, including, but not limited to, the Federal Aviation Administration and/or the operator and did not travel in support of this investigation to prepare this aircraft accident report.

The helicopter landed hard and rolled over during a practice autorotation. The purpose of the flight was for the flight instructor to give the flying pilot the recurrent flight checks required by 14 CFR Part 135. They entered a landing pattern parallel to 22R. At 500 feet above ground level (agl) and 80 knots indicated airspeed (IAS), the flight instructor initiated an engine failure. The pilot responded appropriately and entered an autorotation with 60 knots IAS and 398 rpm rotor speed (Nr). At 60 feet agl, the pilot began the flare; however, it was more aggressive than necessary for the conditions. The pilot then lowered the nose after being advised by the flight instructor to do so. At 30 feet agl, the pilot began to increase the collective; the Nr dropped to 380. The flight instructor announced, "I am on the controls with you," and then, "I have the controls." The flight instructor leveled the helicopter and reduced the collective. About 5 feet agl, the flight instructor initiated the final collective application. As the Nr decreased, the tail rotor lost effectiveness; the helicopter yawed to the left with full right anti-torque pedal applied. The helicopter touched down and the nose was approximately 15 degrees to the left of the direction of travel. The right skid touched down and the helicopter drifted to the right. The helicopter then rolled to the right despite corrective inputs by the flight instructor. The front portion of the right skid dug into the soft turf and pivoted the helicopter forward and the main rotor blades contacted the ground. No mechanical malfunctions were reported.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

the pilot's excessive flare and mistimed collective application during a practice autorotation, which resulted in a loss of main rotor rpm and a subsequent hard landing. Also causal, was the flight instructor's delayed remedial action and inadequate supervision of the flight. The soft terrain was a factor.

Full narrative available

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