Investigation number
199301368
Occurrence date
State
Victoria
Report release date
Report status
Final
Investigation type
Occurrence Investigation
Investigation status
Completed
Aviation occurrence category
Abnormal engine indications
Occurrence class
Incident

While operating in a high out of ground effect hover, the pilot heard a change in the engine noise. He noted that the engine torque needles had split by about 60% with the number two engine torque needle reading high. He also noted that the main rotor revolutions per minute (RPM) had increased to maximum (redline). He assessed the problem as a power turbine governor high-side failure and controlled engine parameters by retarding the power lever for number two engine before performing a gentle run on landing in a nearby paddock. The air pressure line (Pr line) between the power turbine governor and the fuel control unit was found to have broken in the sleeve near the pipe flare where it was attached to the power turbine governor. The broken pipe allowed pressurised air to escape, thereby causing a governor high side failure. The company chief engineer determined that the stainless steel pipe broke because it was misaligned at the fitting to the fuel control unit. This placed the pipe under stress which eventually caused it to break near the other end fitted to the power turbine governor.

Aircraft Details
Manufacturer
Aerospatiale Industries
Model
AS.355F1
Registration
VH-HRA
Sector
Helicopter
Departure point
Port Melbourne Helipad Vic.
Destination
Port Melbourne Helipad Vic.
Damage
Nil