Better Burn Llc/Startube Div EXEC 162F N333ST accident near Chandler, Arizona

Probable cause

The flight instructor's inadequate supervision of the flight and delay in taking remedial action to prevent the helicopter from touching down while drifting. Contributing to the accident was the design of the skid shoes.

NTSB analysis

The flight instructor said the student was practicing a stable hover at 2 to 3 feet altitude, when the helicopter descended with a slight drift to the right. The student said he made a correction and thought the helicopter might touch the ground and lift up again. When the right skid contacted the taxiway, the right rear skid shoe stuck in the asphalt surface and the aircraft rolled right, pivoting on the right skid. The flight instructor immediately bottomed the collective and pushed the cyclic left; however, the aircraft continued to roll onto its right side. Subsequently, the tail boom was bent up and partially separated, the windscreen structure was broken, the main rotor blades were damaged, and the fuselage was wrinkled. The flight instructor said the helicopter belonged to Rotorway, the kit manufacturer, and was used for factory flight training. The company had equipped the skids with prototype skid shoes approximately 10 inches in length that were flat and extended laterally beyond the skids. When the aircraft touched the ground with lateral movement, the aft right skid shoe dug into the asphalt causing the aircraft to roll right. The flight instructor said that after this accident, the company modified the skid shoe design by rounding the shoes to conform to the landing skids.

Text from the NTSB. Open the NTSB docket for WPR09CA198 for the full record.