Aviation safety investigations & reports

Abnormal engine indications involving a Aerospatiale Industries AS.355F1, VH-HRA, 2.5 km N Dandenong, VIC on 17 May 1993

Investigation number:
Status: Completed
Investigation completed


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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.
Download Final Report
[Download  PDF: 12KB]
General details
Date: 17 May 1993   Investigation status: Completed  
Time: 8:30 EST    
State: Victoria   Occurrence type: Abnormal engine indications  
Release date: 18 May 1993   Occurrence category: Incident  
Report status: Final    

Aircraft details

Aircraft details
Aircraft manufacturer Aerospatiale Industries  
Aircraft model AS.355F1  
Aircraft registration VH-HRA  
Sector Helicopter  
Damage to aircraft Nil  
Departure point Port Melbourne Helipad Vic.  
Destination Port Melbourne Helipad Vic.