The pilot had flown the Cessna 172 aircraft, registered VH-DBG, from Derby to Fitzroy Crossing earlier in the day. The pilot reported that, prior to departure from Derby, he had dipped the tanks using a dipstick, which displayed that there was 100 litres of fuel on board. After arrival at Fitzroy Crossing, the pilot added 44 litres of fuel to the aircraft. The pilot reported that he again used the dipstick to check the amount of fuel. He said that the dipstick displayed that there was 100 litres of fuel on board the aircraft.
The aircraft departed from Fitzroy Crossing and the pilot conducted a scenic flight on the return leg to Derby. As the aircraft was approaching Derby, cruising at 3000 ft, the engine began to splutter and then lost power. The pilot turned the aircraft towards a sealed road and, after transmitting a PAN call, conducted a forced landing onto a road. There were no reported injuries. The pilot reported that the flight time for the return flight was 1.8 hours. He also reported that he had leaned the mixture during the cruise portions of the flight in accordance with the engine manufacturer's operating manual. The ATSB did not attend the site, however the investigation was conducted with reference to information provided by the pilot in command, the operator and several other parties.
The pilot arranged for a licensed aircraft maintenance engineer to attend the aircraft on the road. The engineer reported that when he arrived at the aircraft and checked the fuel tanks, there was no useable fuel in either of the tanks. The pilot also reported that there was no useable fuel remaining in the fuel tanks. The engineer then checked the aircraft engine and fuel system and, after adding fuel, the aircraft was flown back to Derby with no reported problems.
Once the aircraft was back at Derby, further checks of the aircraft and its systems were conducted, with no reported defects found. The engineer reported that he added approximately 60 litres of fuel to each tank in 30 litre increments and found that the cockpit fuel gauges were showing quantities that were consistent with the fuel calibration card that was present in the cockpit.
A post occurrence flight plan of the proposed flight, in accordance with the company operations manual, revealed that the aircraft was required to carry 104 litres of fuel. With this amount of fuel onboard the aircraft, and a normal inflight fuel burn, there would have been 43 litres of fuel remaining in the aircraft at the point where the engine stopped.
The operator conducted an investigation into the circumstances of the occurrence. The operator's investigation found that the dipstick used by the pilot in command to check the fuel quantity incorrectly indicated unusable fuel as useable fuel. The amount of unusable fuel totalled 23 litres.
The pilot was forced to land on a road when the useable fuel on board the aircraft had been consumed. The aircraft fuel quantity had been verified with an incorrect fuel dipstick that indicated unusable fuel as being useable fuel. The aircraft fuel gauges were capable of indicating fuel quantities that were consistent with the last fuel calibration card in the cockpit.
The incorrect markings on the dipstick accounted for a fuel discrepancy of 23 litres. The investigation could not determine the source of the remaining 20 litre fuel discrepancy.
Local Safety Action
The operator advised that, following the occurrence, the aircraft involved was equipped with a new dipstick. An accuracy check was also conducted on the dipsticks fitted to other aircraft in the operator's fleet.
|Date:||22 January 2004||Investigation status:||Completed|
|Time:||1315 hours WST|
|Location:||19 km E Derby, Aero.|
|State:||Western Australia||Occurrence type:||Fuel exhaustion|
|Release date:||07 June 2004||Occurrence category:||Incident|
|Report status:||Final||Highest injury level:||None|
|Aircraft manufacturer||Cessna Aircraft Company|
|Type of operation||Charter|
|Damage to aircraft||Nil|
|Departure point||Fitzroy Crossing, WA|
|Departure time||1145 hours WST|
|Role||Class of licence||Hours on type||Hours total|