NTSB

The pilot receiving instruction’s failure to extend the landing gear. Contributing to the accident were the pilot receiving instruction’s failure to complete the landing checklist and the flight instructor’s inadequate monitoring of the pilot.

The pilot’s failure to maintain directional control during an attempted go-around, which resulted in impact with a snowbank.

Contamination of and an inadequate bond between the two layers of fabric comprising the helicopter engine’s air induction inlet duct, which resulted a partial collapse of the duct, obstruction of the airflow into the engine, and a total loss of engine power.

The pilot’s failure to maintain directional control during landing, which resulted in a runway excursion and impact with a ditch.

The pilot’s selection of unsuitable terrain for landing, which resulted in a nose-over.

The pilot’s failure to maintain lateral control in flight and his subsequent loss of directional control during landing with a crosswind, which resulted in a runway excursion and impact with terrain.

The pilot’s failure to extend the landing gear before landing.

The pilot’s failure to maintain directional control during the landing roll and his exceedance of the airplane’s critical angle of attack when it inadvertently became airborne, which resulted in an aerodynamic stall.

The pilot’s delayed decision to abort the takeoff, which resulted in a runway overrun, impact with a fence, and a nose-over.