Aviation safety investigations & reports

Engine cooling fan fracture - VH-IDU, Rolleston Queensland, 3 May 2009

Investigation number:
Status: Completed
Investigation completed


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On 3 May 2009 at approximately 0620 Eastern Standard Time, a Bell Helicopter Company model 47G-2A-1 helicopter departed Rolleston aircraft landing area, Queensland, on a private flight. At an altitude of approximately 200 ft above ground level during the climbout, the pilot reported hearing a very loud bang and feeling a jolt through the airframe. The helicopter immediately started descending and the pilot noted that the forward/aft cyclic control was unresponsive. The helicopter subsequently landed heavily, resulting in the main rotor blades severing the tail boom and causing some structural damage to the airframe. The pilot reported suffering a minor back injury as a result of the heavy landing.

The Australian Transport Safety Bureau's (ATSB) examination of the helicopter revealed that two blades had separated from the engine cooling fan as a result of fatigue fracture. The fan cowling had fractured and separated from the engine and there was impact damage to the flight control linkages.

The ATSB examination determined that the fan unit had not been correctly assembled in accordance the Bell 47 aircraft maintenance manual, and that this probably had an effect on the vibration and resonance characteristics of the fan, which in turn may have increased the susceptibility of the fan to fatigue failure.

As a result of this occurrence, the Civil Aviation Safety Authority released Airworthiness Bulletin AWB 63-007, reminding operators and maintainers of the importance of adhering to all current manufacturer's approved data for sheet metal cooling fans and their drive assemblies.

Download Final Report
[Download  PDF: 512KB]
General details
Date: 03 May 2009   Investigation status: Completed  
Time: 0620 EST   Investigation level: Systemic - click for an explanation of investigation levels  
Location   (show map): Rolleston (ALA)    
State: Queensland   Occurrence type: Powerplant/propulsion - Other  
Release date: 21 May 2010   Occurrence category: Accident  
Report status: Final   Highest injury level: Minor  

Aircraft details

Aircraft details
Aircraft manufacturer Bell Helicopter Co  
Aircraft model 47  
Aircraft registration VH-IDU  
Serial number 6765  
Type of operation Private  
Sector Helicopter  
Damage to aircraft Substantial  
Departure point Rolleston, Qld  
Destination Rolleston, Qld  
Last update 03 April 2020