Aviation safety investigations & reports

Fuel exhaustion involving a Cessna Aircraft Company T303, VH-AOV, Near Yarram, VIC on 19 December 1993

Investigation number:
199304156
Status: Completed
Investigation completed

Summary

Circumstances The pilot was undertaking a private flight with four people on board. The aircraft was en route from Flinders Island to Essendon when the right engine suddenly stopped. The pilot reported that he suspected that the right fuel tank was empty, even though both gauges were indicating full. The engine was restarted after switching to obtain fuel from the left tank. Some ten minutes later both engines stopped. The pilot feathered both propellers and diverted towards the landing strip at Yarrum. The aircraft was landed just short of the strip breaking off the left landing gear and left engine. The four persons on board evacuated without injury. The aircraft fuel tanks were found to be essentially empty. There was no evidence of external leakage. The pilot regularly flew two return flights (four sectors) from Essendon to Flinders Island on a full tank of fuel and the accident flight was the last leg of such a sequence. It was determined that prior to the sequence of four flights the pilot's wife, also a licensed pilot but not rated on the type, had telephoned the maintenance organisation who prepared their aircraft requesting that the tanks only be filled to three quarters capacity. This was to provide a lower weight for a possible intermediate landing. The maintenance personnel were not sure that they could accurately determine three quarters capacity and filled the tanks until both gauges read just in excess of three quarters and the fuel level at the tank filler was visually seen to be one inch above the bottom of the tank. The pilot said that prior to the first flight of the sequence he visually assessed the quantity and considered the tanks to be full. Accordingly, his conduct of the sequence of flights was based on this assessment, and on his calculations of fuel usage during the flights. Due to the dihedral of the wings and the position of the fuel filler at the wing tip it is not possible to make a visual assessment of the fuel quantity once the fuel level has dropped below about three quarters capacity. Consequently, no visual assessments were made prior to the next three takeoffs. The pilot did not add fuel prior to those takeoffs even though fuel was available. Post accident calibration of the fuel flow system disclosed that the engines were consuming very slightly more fuel than shown by the fuel flow gauges. A fuel tank quantity indication system calibration carried out in February 1992 showed that the indications were not linear. A calibration chart was provided which showed the correct quantities at each indicator division. There had been no deficiencies recorded on the maintenance release in relation to either the fuel quantity or fuel flow indication systems. After the accident the fuel quantity indication system for the right wing was found serviceable, the left wing system was unserviceable, most probably due to impact damage. Calculations of fuel used over the four sectors flown until the aircraft ran out of fuel show that the tanks would have had to be approximately 80% full when the aircraft commenced the flight sequence. There was no evidence that fuel was pilfered while the aircraft was left unattended. Significant Factors The following factors were considered relevant to the development of the accident. 1. The aircraft was fuelled to less than full tanks. 2. The pilot incorrectly believed that he had commenced the four sector sequence with full tanks. 3. No visual check of fuel quantity was possible once the quantity was below approximately 75% full. 4. The fuel flow indicating system was inaccurate. 5. The pilot assessed that there was sufficient fuel for the flight on the basis of: . a belief that he had commenced the four sector sequence with full tanks, . his knowledge of the fuel consumption rates of the engines, . the elapsed time of the first three sectors, and . fuel quantity gauge indications. 6. The aircraft fuel tanks did not contain sufficient fuel for the flight.
General details
Date: 19 December 1993   Investigation status: Completed  
Time: 20:03 ESuT    
State: Victoria   Occurrence type: Fuel exhaustion  
Release date: 13 October 1994   Occurrence category: Accident  
Report status: Final    

Aircraft details

Aircraft details
Aircraft manufacturer Cessna Aircraft Company  
Aircraft model T303  
Aircraft registration VH-AOV  
Sector Piston  
Damage to aircraft Substantial  
Departure point Flinders Is TAS  
Destination Essendon VIC