Bell 47 Safety Record

The failure of the ignition switch leading to an engine power loss in cruise flight and the subsequent high flare during autorotation. Factors contributing to the accident were the pilot's misjudgment of the landing flare and the unsuitable terrain encountered by the pilot on landing.

separation of the no. 6 cylinder intake valve head from the valve stem, which resulted in a loss of engine power. The mechanism responsible for the valve failure is unknown.

The pilots inadequate fuel management, and subsequent loss of engine power due to fuel exhaustion, and a in-flight collision with trees during an autorotation. A factor was the pilot's failure to insure that the required equipment (fuel gauge) was installed in the helicopter.

the failure and separation of a fan belt for the engine cooling system. A factor in the accident was the inadequate annual inspection 14 hours prior to the accident.

the pilot's inadvertent in-flight encounter with severe turbulence, which resulted in main rotor-tailboom contact and the separation of the tailrotor drive shaft.

The failure of the student pilot to secure the rotorcraft floorboard mounted ballast, resulting in shifting of the ballast on liftoff, and the subsequent dynamic rollover.

The pilot did not maintain directional control during hover taxi. Inadequate compensation for the crosswind conditions, the light rain, and the light pole were factors in the accident.

The pilot's failure to maintain clearance of a tree while maneuvering, which resulted in an in-flight collision with the tree and subsequent uncontrolled descent and collision with terrain.

the flight instructor's selection of an unsuitable area for practicing a full touchdown autorotation, which resulted in a nose over. A contributing factor was the soft ground.

The failure of the main rotor system stabilizer damper control horn assembly, resulting in an uncontrolled descent and subsequent collision with a tree and terrain.

The reported loss of engine power for undetermined reasons during a the cruise portion of a CFR part 137 observation, and the pilot not following the height/velocity charts data.

The pilot's improper use of flight controls during an autorotation that resulted inn the collapse of the skids and cross tube assembly. A factor was the loss of engine power due to the failure of # 1 connecting rod and the overload failure of the skids and cross tub assembly.

The engine crankshaft's failure as the result of fatigue cracking initiated by surface damage and localized overheating due to the installation at overhaul of incorrectly sized bearings.

The pilot's inadequate in-flight planning that resulted in settling with power during an aerial application turn-to-reverse direction and collision with the ground. Factors were high density altitude and a wind shift.

the loss of tail rotor control during maneuvering resultant from the failure of the tail rotor drive shaft coupling due to a stripped thread which allowed the grease lubricating the shaft to leak out. A factor was the lack of suitable terrain for the forced landing (autorotation).