On 8 June 2013, the pilot of a Bell LongRanger helicopter, registered VH-RHF, was conducting an aerial survey flight with four passengers in the Buccaneer Archipelago area north of Derby, Western Australia. The helicopter was being flown at about 1,000 ft to a planned fuel stop on an island in Cone Bay and was over water when the engine flamed out.
The pilot entered autorotation to glide towards land but was unable to reach it. During the glide the pilot deployed the helicopter’s pop-out floats in preparation for an emergency ditching. Shortly after touchdown the helicopter rolled inverted. The pilot and the four passengers exited without injury. A boat crew observed the emergency landing and rescued the occupants from on top of the upturned floating helicopter.
What the ATSB found
The ATSB found that, without the pilot realising, the fuel on board was probably sufficiently low to allow momentary un-porting of the fuel boost pumps, which interrupted the flow of fuel to the engine, resulting in an engine flame-out and ditching. Contributing to the pilot’s lack of awareness of the fuel state was a likely malfunction of the helicopter’s fuel quantity indicating system and a faulty low fuel caution system. In addition, the operator’s fuel management system was almost totally reliant on the fuel quantity indicating system and as a consequence, lacked a high level of assurance.
The ATSB also found that the guidance provided by the Civil Aviation Safety Authority in relation to pre-flight crosschecking of fuel on board allowed for a reliance on aircraft fuel quantity indicating systems without reference to independent sources of fuel quantity information.
What has been done as a result
The helicopter operator advised that as a result of this occurrence they have redesigned their fuel tracking form to improve usability. In addition, the operator is considering the fitment of a fuel totaliser to their LongRanger helicopter types.
As shown by this and other occurrences, there is a need for operators to ensure that their fuel management policy and procedures provide for at least two independent and reliable means of establishing fuel on board. These should be supplemented by criteria for identifying, recording, and resolving any discrepancy between the amounts generated by the different methods. In situations where visual or other direct means of establishing fuel quantity are not possible, equipment that measures and totalises fuel flow can provide a valid basis for derivation of fuel on board.
Low fuel level caution systems are valuable elements in a safe fuel management framework but can fail without detection and should not be relied upon as a substitute for an independent crosscheck of fuel quantity indicating systems. Operators should consider the criticality of on-board fuel quantity measuring equipment in the context of their particular operations and manage the risk of malfunction accordingly.