Bell 47 Safety Record

Maintenance personnel’s failure to safety wire the throttle control adapter per maintenance instructions when the carburetor was replaced and to detect that the adapter was not safety wired during the annual inspection, which resulted in the throttle control disconnecting and subsequent loss of engine control.

The failure of the helicopter’s center frame tube due to a fatigue crack and corrosion originating from a welded surface. Contributing to the accident was maintenance personnel’s inadequate inspection of the helicopter during its most recent 100-hour inspection.

The pilot's operation of the helicopter at high gross weight and high density altitude while still in ground effect, which reduced the efficiency of the rotor system and the amount of lift produced, which resulted in a collision with terrain. Contributing to the accident was the pilot's decision to continue the flight after the first indication of reduced performance.

The improper rebuild and maintenance of the helicopter and inadequate subsequent inspections, which resulted in undetected fuel contamination and a subsequent total loss of engine power during cruise flight.

The flight instructor's inadequate supervision of the student pilot during a simulated autorotation and the pilots’ failure to use carburetor heat while operating at reduced engine power while in carburetor icing conditions, which resulted in a loss of engine power.

The pilot’s inadequate preflight, and contamination of both the engine compressor section and the main rotor blades, which resulted in reduced performance of the engine and rotor system.

A loss of control during the precautionary landing, which resulted in inadvertent contact between the main rotor and the tailboom. Contributing to the accident was the overloaded condition.

The pilot’s inadequate compensation for a wind shift encountered during the landing approach, which resulted in a hard landing and rollover. Contributing to the accident was the encounter with the wind shift.

The loss of engine power during an aerial application flight due to a fatigue fracture of the carburetor heat control valve spring and the inadequate maintenance inspection by the pilot/mechanic. An additional cause was the low altitude of the operation.

The pilot's failure to maintain adequate altitude while maneuvering. Contributing factors were the failure of the helicopter's lights during the night flight and the effect of that failure on the pilot's visual perception.

The plot's distraction with the chemical load resulting the failure to maintain control of the helicopter. A factor was no suitable terrain for landing.