Total power loss involving a Hiller UH-12E, VH-AGK, 28 km south of Smithton, Tasmania, on 23 January 1993

During the procedure turn at the end of a spray run the engine power failed. During the ensuing forced landing the pilot had to overpitch the rotor to avoid power lines. The helicopter landed heavily fracturing the tail boom, damaging the main rotor blades, and collapsing the skids.

Inspection of the engine disclosed that the left exhaust pipe had fractured inside the carburettor heat shroud. The exhaust gases were then ingested by the engine with consequent total loss of power.

The exhaust pipe fracture was caused by fatigue occasioned by the unsupported nature of the installation. The shroud would have masked the fracture growth, which was not in evidence at the last inspection some 40 hours prior to failure.

Significant Factors

1. The engine power failed due to a fractured exhaust pipe.

2. The pilot was forced to overpitch to avoid obstructions.

3. The helicopter landed heavily.