Fuel exhaustion

The pilot was operating over his property on a stock spotting flight with his brother as passenger. He had departed with about 2.5 hours fuel on board but, after about 40 minutes, the aircraft fuel gauges seemed to indicate a loss of fuel. The pilot headed for the station airstrip, but the engine failed when the aircraft was about 4 km south of the strip. The pilot selected an area for a forced landing, but the aircraft struck a fence and some bushes before coming to a stop.

Substantial damage was caused to the left wing and flap, left hand lift strut, the landing gear was stressed and gouges cut in the propellor blades and hub. The left hand fuel cap was missing allowing fuel to escape from the tank by siphon action. The pilot made temporary repairs to this substantial damage and later flew the aircraft to Swan Hill for repairs, a distance of over 480 km.

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 take-offs. The pilot did not add fuel prior to those take-offs 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. a belief that he had commenced the four sector sequence with full tanks,

b. his knowledge of the fuel consumption rates of the engines,

c. the elapsed time of the first three sectors, and

d. fuel quantity gauge indications.

6. The aircraft fuel tanks did not contain sufficient fuel for the flight.

The pilot made a mayday call reporting that the engine had failed at 400 feet over Port Stephens. As there was insufficient altitude to reach the shore, the pilot ditched in the water. Both occupants managed to evacuate the aircraft before it sank.

After recovery from the water, investigation revealed only the unusable fuel quantity remained in the tanks and the fuel strainer and carburettor bowl were empty. No mechanical defects were found with the aircraft apart from salt contamination.

The pilot had flown the aircraft from Tasmania. He refuelled at Maroochydore on his way north and had undertaken some flights in the area prior to commencing his return journey. The aircraft departed Noosa and after a flight of about 10 minutes entered the circuit at Maroochydore. There was a northerly wind of 20 to 25 knots and the aircraft was cleared to land on runway 36.

On final approach the engine stopped and the pilot was unable to restore power. The aircraft was landed short of the runway and outside the airfield boundary in rough terrain. Neither occupant was injured. The pilot had not kept accurate records of flight times flown for each leg. He had calculated time intervals for each leg and had subtracted these times from this original endurance to calculate the endurance before commencing the next leg.

As a result, he did not have an accurate knowledge of the quantity of fuel remaining in the aircraft tanks prior to commencing any leg, other than the leg immediately after refuelling the aircraft. Prior to commencing the final flight the pilot had assessed that he had sufficient fuel to undertake the flight using the above method.

SIGNIFICANT FACTORS

1. The pilot did not keep adequate records of fuel usage.

2. The pilot did not ensure that there was adequate fuel in the aircraft prior to commencing the flight.

The pilot had flown from Bankstown to Baradine and return on many occasions in VH-FMB. Prior to departure from Bankstown on the day before the accident, the aircraft's fuel tanks were filled to the maximum capacity of 285 litres. On arrival at Baradine the pilot added 50 litres of motor spirit. The aircraft was parked on the apron at Baradine airport.

The following morning the pilot visually checked the fuel contents but did not use a dip stick. During a water drain check, 5-6 cups of water were taken from the under-fuselage drain point.

The return flight proceeded normally until the aircraft was about 20 kms north of Bankstown airport. The engine then began to run intermittently, followed by a complete loss of power. At this time the fuel gauges indicated that about 1/4 of the fuel capacity in each tank remained. The pilot declared an emergency and conducted a forced landing on cleared land near Winston Hills shopping centre. During the landing roll the nose gear leg was torn from its mounting.

The loss of engine power was determined to be the result of fuel exhaustion. The pilot had calculated the fuel tanks should have contained 100 litres at the time of the power loss. He concluded that about 100 litres of fuel was removed from the aircraft whilst it was parked at Baradine overnight. The aircraft fuel gauges were evidently over reading.

The aircraft struck an obstacle during an attempted forced landing.

Inspection found that the engine had stopped when the fuel on board had been exhausted after 40 minutes flying. The pilot reported that the tanks were half full prior to departure. This should have been sufficient fuel for about two and a half hours flying. No evidence was found of any fuel leaks.

During an IFR pre-licence test the pilot of a Beech 76 aircraft, enroute from Maitland to Bankstown, made a MAYDAY call advising that both engines had failed. No location was given and the pilot did not respond to calls from Flight Service. A distress phase was declared and the appropriate authorities notified. A short time later a telephone call was received from the operator, advising that the aircraft had made a forced landing on the Galston sports oval. Both occupants were uninjured, although the aircraft was substantially damaged. Emergency services were in attendance. The distress phase was then cancelled.

The aircraft had touched down on a small sporting oval, but the pilot was unable to stop within the confines of the field. The aircraft struck the top of an embankment, where the left wingtip collided with a power pole, and the right main landing gear was torn off. The aircraft then collided with a chain mesh fence, coming to rest in a right wing low attitude.

The pilot subsequently reported that about ten minutes prior the event, whilst at 6,000 ft, the left engine had surged and stopped. The propeller was feathered and the fuel crossfeed was selected to the right tank. The engine was restarted and developed normal power. The aircraft was then descended to 1,500 ft, but shortly after, both engines began to surge, causing the aircraft to yaw violently. A MAYDAY call was transmitted but there was insufficient time to report position before the forced landing.

The investigation determined that only an unusable quantity of fuel remained on board the aircraft after the accident. Although both left and right fuel tanks had been holed during the accident sequence, testing determined that both tanks were capable of retaining substantial quantities of fuel whilst the aircraft remained in the right wing low attitude at the accident site. An examination of fuel records determined that the aircraft had not been refueled on the day of the accident. Calculations using the previous recorded flying times, and fuel uplifts on the day prior to the accident, determined there had been insufficient fuel on board, prior to takeoff, to complete the flight.

The aircraft was being used to spray crops approximately 600 m from the strip being used for take-offs and landings. The aircraft engine lost power during a spray run and the pilot elected to land straight ahead into the field of barley. After touchdown, the aircraft ground looped, causing some damage to the port wing trailing edge and aileron. The pilot noted after landing that the fuel transfer warning light was illuminated and he later found that there was only a small amount of fuel in the main fuel tanks.

The pilot reported that he had noted the aircraft's low fuel state before take-off but decided to fly until the fuel transfer warning light illuminated. The fuel transfer warning light illuminates when the fuel pressure at the inlet to the header tank falls below approximately 14 kpa for a sustained period, indicating that the mechanical fuel pump is not delivering fuel to the header tank or that the main fuel tanks have run dry. The pilot believed that he could return to the strip before fuel exhaustion caused the engine to fail.

With regard to the fuel transfer warning light, the aircraft flight manual states in part: "In the latter case, although the contents of the header tank has been declared "unuseable fuel" due to certification regulations, the remaining 12 litres of fuel in the header tank should in fact be available and sufficient for at least 12 minutes of further flight at normal power settings and aircraft attitudes". The aircraft was fitted with a Global Positioning System (GPS) tracking bar with a series of red lights to indicate lateral displacement from the desired flight path.

The GPS bar assists the pilot to correctly align the swath runs. The pilot reported that each of the GPS bar lights was similar in appearance to the fuel transfer warning light located in the coaming above the instrument panel. The fuel transfer warning light glowed a steady red when illuminated. The GPS bar was mounted in the accident aircraft such that it was directly in the pilot's line of sight, appearing just to the left of, and very near to, the fuel transfer warning light. The pilot reported that during the spray runs, he was concentrating on avoiding powerlines and was referring to the GPS bar.

He had not noticed the illumination of the fuel transfer warning light during the flight. The pilot noted after landing that the fuel transfer warning light was on; therefore, it had probably operated correctly. However, because the pilot's attention was drawn to avoiding powerlines as well as using the GPS bar, he failed to notice the illumination of the fuel transfer warning light during the flight. The proximity and similiarity of the GPS bar lights to the fuel transfer warning light probably contributed to the pilot not noticing the illumination of the fuel transfer warning light.

The pilot's decisions to rely on the fuel transfer warning light and to plan the use of the header tank fuel were probably encouraged by the aircraft's flight manual wording on unuseable fuel. The wording indicates that the unuseable fuel is useable.

SAFETY ACTION

The Bureau is considering the safety implications of the wording contained in the aircraft flight manual regarding the use of "unuseable" fuel from the header tank. Any safety action arising from the investigation of this matter will be forwarded to the relevant action agencies and will be published in the Bureau's Quarterly Safety Deficiency Report.

Piper Chieftain aircraft, VH-RDL, departed Boonoke (a property near Deniliquin) on a charter flight to Sydney in accordance with the Instrument Flight Rules, with a planned intermediate refuelling stop at Cootamundra. As the aircraft approached the Cootamundra circuit area the left engine began to surge. The pilot commenced a straight-in approach to the 10 grass runway, however the right engine also began to surge and lose power.

The aircraft was landed in a paddock, some 400 metres before the beginning of grass strip 10. During the ensuing ground roll the pilot was able to manoeuvre the aircraft over a shallow creek bed and a fence. The aircraft then passed through the aerodrome boundary fence before stopping on the runway. The nine passengers and pilot escaped without injury. The aircraft was substantially damaged.

During a subsequent examination of the aircraft it was determined that all useable fuel had been exhausted from both inboard tanks. The left outboard fuel tank contained 11 litres, while the right outboard tank contained 30 litres.

The Chieftain was one of a number of aircraft chartered to carry a large group of people to and from Boonoke during the weekend of 18-19 October. On the evening of 17 October, the operator briefed all pilots associated with the proposed charter on how the operation was to be conducted. During the briefing the operator said that he had arranged with fuel agents at Deniliquin and Cootamundra to provide fuel as required. Fuel purchases were to be placed on the operators account. Refreshments had also been arranged for passengers at Cootamundra while refuelling was taking place.

On the afternoon of 18 October VH-RDL was ferried from Bankstown to Sydney, having departed Bankstown with some 602 litres of fuel, comprised of full inboard tanks, and 100 litres in each of the two outboard tanks. After arriving at Sydney another pilot took command of the aircraft and flew nine passengers to Deniliquin. No fuel was added to the fuel tanks after the aircraft left Bankstown.

The following afternoon VH-RDL, which had remained at Deniliquin, was scheduled to take nine passengers from Boonoke to Sydney. A pilot who had flown another Chieftain, VH-XML, from Sydney to Deniliquin the previous evening, was tasked to carry out the return flight in VH-RDL. Prior to departing Deniliquin the pilot he said he carried out a Daily Inspection. His first action was to turn on the master switch and check the fuel contents indicators. He also opened both inboard tank caps to carry out a visual contents check. Although the tank interiors were in shadow he thought he could just see fuel, but he could not touch it. Based on his observations, and a comparison of the estimated fuel burn from Bankstown, he estimated the fuel remaining totalled 280 litres, whereas he had calculated he required 257 litres to fly to Cootamundra via Boonoke, including appropriate fuel reserves. The pilot also said that it was his understanding from the earlier briefing that each aircraft should carry sufficient fuel from Sydney to allow a return to Cootamundra via Boonoke before refuelling. He believed that it was preferable not to refuel at Deniliquin, although he felt that if he needed fuel it would not have been a problem obtaining it.

Another pilot reported that he spoke to the pilot of VH-RDL prior to the flight and suggested that the aircraft be refuelled prior to departing from Deniliquin, to eliminate the need to land en-route. However, the pilot of VH-RDL indicated he would refuel at Cootamundra, which would also provide for a passenger "comfort stop".

The aircraft was duly flown to Boonoke, to take on passengers, before departing for Cootamundra. After take-off the aircraft was climbed to its planned cruising altitude of 9,000 ft, drawing fuel from the inboard tanks. Once established in level flight the outboard tanks were selected and fuel was drawn from those tanks until commencing descent, some 16 minutes before the estimated time of arrival at Cootamundra. At about that point the pilot moved the fuel selectors to draw fuel from the inboard tanks. He said the outboard fuel contents gauges were indicating empty, and he had been monitoring the engine exhaust gas temperature gauges for initial indications of exhaustion of the outboard tanks. However, no indications were noticed before he reselected the inboard tanks, in accordance with a Flight Manual limitation to only use the outboard tanks in level flight. The pilot said he thought the inboard fuel tank contents were indicating between 1/4 and 1/2 full. At that stage he said he had no concerns about the amount of fuel remaining.

As the aircraft approached the Cootamundra circuit area the left engine began to surge. The pilot looked at the left fuel gauge and noted it was indicating below 1/4. He selected the left outboard tank and turned on the boost pump. The engine continued to surge briefly before operating normally. He then turned off the boost pump. At that point the aircraft was at an altitude of some 3,500-4,000 ft. Shortly after, the left engine again commenced to surge. The pilot said he again turned on the left boost pump and moved the fuel selector to run both engines from the right inboard tank via the fuel crossfeed.

With the aircraft still descending the pilot elected to carry out a straight-in approach to land on the 10 grass runway, joining final approach at an altitude of about 3,000 ft. Because the aircraft appeared to be high the landing gear was extended. However, both engines began to surge and lose power. Because the pilot was unsure if the aircraft could reach the runway threshold he elected to land short in an adjoining paddock, progressively extending flap prior to touchdown.

A subsequent investigation found that Chieftain, VH-XML, had carried out a similar flight to VH-RDL, from Sydney to Cootamundra, via Deniliquin and Boonoke. However, that aircraft had departed Sydney with full tanks, and was found to have used 551.17 litres upon arrival at Cootamundra. The useable capacity of both inboard and outboard tanks of the Chieftain totals 690 litres. The fuel remaining in VH-RDL after the accident was 41 litres. When compared to the fuel burn of VH-XML, the total fuel on board VH-RDL when it departed Sydney would have been about 590 litres.

The actual fuel carried in the aircraft on departure from Boonoke was probably about 190 litres, some 67 litres less than the minimum fuel required, including reserves.

The pilot commenced a business trip to Boonah and return with 65 to 70 litres of fuel on board the aircraft. Approaching Toowoomba on the return flight, a landing gear down indication was not obtained. The pilot arranged for ground observers to inspect the landing gear while he overflew the airstrip, having pulled the landing gear pump circuit breaker. One pass was flown towards the east, followed by a reversal turn and an overfly towards the west. Conscious that the fuel was getting low, the pilot conducted a right turn with the intention of landing. Around this time the engine stopped. The pilot did not have time to select the other fuel tank, nor to reset the landing gear circuit breaker, as had been his intention prior to landing.

The aircraft was landed on a road but the left wing collided with a pole. The landing gear down light was reported to be on after the landing. Prior to undertaking the flight the pilot considered that about 45 litres of fuel would be used. He normally intended having about 30 minutes of fixed reserve, however he was pressed for time on this occasion and accepted less. The investigation found that the flight as conducted should have consumed about 67 litres of fuel. Only about three litres of fuel were recovered from the reservoir tanks after the landing. No fuel was found in the wing tanks.