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The pilot was conducting joy flights in the vicinity of an active car race track. The helicopter type was recently introduced into Australia and is a relatively new design. VH-APM had accrued only 128 hours total time since new. The pilot took off into a 15 knot wind with three passengers on board. The helicopter was operating at less than maximum gross weight, with a significant power margin. The pilot advised that when the helicopter was about 100 feet above the ground, climbing at about 55 knots, he felt a slight airframe vibration and heard the engine noise increase slightly. The vibration level continued to worsen. The pilot had no idea what was causing the vibration or how serious it was. He elected to land the helicopter as soon as possible. As there was no suitable landing site immediately ahead, he turned back to the departure helipad and instigated a power-on (needles joined) autorotative descent. Nearing the ground the pilot flared the helicopter, which was facing downwind, and applied maximum power, but was unable to eliminate the rate of descent. The helicopter sank through the flare and landed heavily, tail low, short of the helipad, in the clear takeoff departure path area, with five to 10 knots groundspeed. Subsequently engineers discovered that the engine cooling fan had come loose on its shaft thereby causing the vibration. A crack was also discovered on the forward face of the fanwheel. CONCLUSIONS Findings 1. The engine cooling fan came loose on its drive shaft. 2. The loose cooling fan caused a vibration through the airframe. 3. The loose fan may have caused the engine to "hunt". 4. The pilot did not know what was causing the worsening vibration. 5. The nearest suitable site for a landing was the departure helipad. 6. In an attempt to land the helicopter as soon as possible, the pilot entered a power on autorotation and terminated with a downwind flare. 7. The helicopter landed heavily with the tail low. Significant Factors The following factors were considered relevant to the development of the accident: 1. The pilot reacted quickly to a sudden, unusual, worsening vibration in flight. 2. Because of the tailwind effect, combined with a rapid descent plus a nose high flare, versus the available power, the pilot was unable to arrest the descent. SAFETY ACTION The helicopter manufacturer issued R44 Service Bulletin #2 on 24 October 1994 to all R44 owners, operators and service centres for an inspection to be done on cooling fans within 10 flight hours and thereafter every 25 hours until the fanwheel is replaced with a D174-1 Rev. G or later fanwheel.
Download Final Report
[ Download PDF: 16KB]
General details
Date: 25 September 1994 Investigation status: Completed 
Time: 15:30 EST  
 Investigation type: Occurrence Investigation 
 Occurrence type: Abnormal engine indications 
Release date: 31 October 1994 Occurrence class: Technical 
Report status: Final Occurrence category: Accident 
Aircraft details
Aircraft manufacturer: Robinson Helicopter Co 
Aircraft model: R44 
Aircraft registration: VH-APM 
Sector: Helicopter 
Damage to aircraft: Substantial 
Departure point:Winton VIC
Destination:Winton VIC
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Last update 21 October 2014