Fuel starvation

On 1 June 2006, at about 0848 Central Standard Time, a Beech Aircraft Corp A36 Bonanza aircraft, registered VH-JDJ, was approaching to land at Bathurst Island aerodrome.

Air traffic services radar data recorded the aircraft overflying the aerodrome and that the pilot joined the circuit on left downwind for a landing on runway 15. The aircraft impacted terrain 2.4 km north-west of the aerodrome. The pilot, who was the sole occupant of the aircraft, sustained fatal injuries.

The aircraft was assessed as being intact prior to the impact with terrain and no anomaly was identified with the aircraft that could have affected its normal operation.

Data recovered from an onboard engine data recording system was consistent with an interruption of the fuel flow and the loss of engine power about 42 seconds before impact. The pilot may have been attempting to perform an emergency landing to a nearby clearing when control of the aircraft was lost.

The engine failed after exhaustion of the fuel from the selected tank. Despite the pilot's engine failure recovery actions, 700 to 800 ft of altitude was lost before the engine restarted. If the engine failure had occurred while the aircraft was below 700 ft AGL, it would have resulted in a forced landing.

The different fuel management procedures at the two operational bases led to the inappropriate fuel selector position for operations from Jabiru. The pilot then overlooked the specific fuel tank selection during the pre-flight checks, because he had an expectation that it would already be appropriately positioned. During both the preceding and the occurrence flight, the fuel gauges had the potential to alert the pilot to the developing unsafe condition. This required reliable fuel gauges and regular comparison of their indications with planned fuel usage and fuel tank selection.

The pilot's response to the engine failure was not consistent with the aircraft manufacturer's or the operator's emergency and abnormal checklist instructions. It is likely that sustained operation of the auxiliary fuel pump introduced excessive fuel into the engine preventing an immediate restart. Selection of the fuel pump to the OFF position after priming the engine in accordance with the operator's Cessna 207 emergency and abnormal checklist should have resulted in a quicker restart with minimal altitude loss.

Although the pilot had read the operations manual that contained the relevant checklist, the operator did not require him to be able to recall the specific checklist items following an engine failure. The operator's induction training did not ensure that the pilot was able to follow the type-specific procedure when responding to an engine failure at a relatively low altitude. Standard operating procedures are an accepted means of reducing the risk of aircraft operation. By allowing the use of procedures that were inconsistent with the operations manual, the operator reduced the effectiveness of that risk control.

The chief pilot's belief that emergency procedures learned during early training could be effectively applied to any general aviation aircraft did not allow for significant variations between aircraft systems and in particular fuel systems. For example, the in-flight engine restart procedure for a low-wing aircraft with a carburetted engine that is commonly used for initial flight training is significantly different from the engine restart procedure for the Cessna 207, which is a high-wing aircraft with a fuel injected engine.

Induction training that facilitated memorisation of the Cessna 207 `engine failure during flight (restart procedures)' checklist with the opportunity for in-flight simulated engine failures would have decreased the risk of an inappropriate response to an engine failure.

The Australian Transport Safety Bureau did not conduct an on-scene investigation of this occurrence.

During the early afternoon of 30 August 2004, the pilot and six passengers onboard a Cessna Aircraft Company 207 Stationair (Cessna 207) departed Jabiru, NT for a 30 minute scenic charter flight.

The pilot reported that about 10 minutes after departure and while cruising at about 1,500 ft above ground level (AGL), the engine abruptly failed. The pilot reset the mixture and throttle controls, changed the selector position from the left to the right fuel tank, switched the auxiliary fuel pump to ON and established a glide speed of 80 kts. When the engine did not immediately respond, the pilot positioned the aircraft for a forced landing at a nearby outstation airstrip. At about 750 ft AGL the engine restarted. Unsure of why the engine had lost power, the pilot continued with the approach and transmitted a PAN alert. When assured of a landing he shut down the engine as a precaution against fire and landed.

The left fuel tank was found to contain no usable fuel and the right tank about 100L. The aircraft was ferried back to Jabiru with the right fuel tank selected and was operated on subsequent flights without incident.

The day before the occurrence, the aircraft was relocated to Jabiru from a remote base. The procedure at the remote base was to use the left fuel tank for flight fuel, and the right tank for reserve fuel. The fuel selector was positioned to the left tank when the aircraft arrived at Jabiru. However, for scenic flights from Jabiru the procedure was the opposite. The aircraft was refuelled to provide 40L reserve in the left tank and 100L in the right tank. The operator advised that these procedures were intended to reduce the risk of fuel starvation during scenic flights.

Early on the day of the occurrence, the pilot conducted a daily inspection of the aircraft and by dipping the tanks, visually confirmed that the fuel quantity accorded with the operator's procedure. He then conducted a 30 minute scenic flight without incident. As the total fuel on board for the occurrence flight was adequate, the quantity of fuel in each tank was not verified visually. The operator stated that the fuel gauges were serviceable. However, the pilot stated that the fuel gauge indicators constantly flickered between full and empty, which prompted him to disregard them.

The operator's maintenance controller informed the ATSB that the maintenance release had not been annotated with details of a fuel gauge defect. A check following the incident revealed that the indications on the aircraft's fuel gauges matched the dip stick measurements for the left and right fuel tanks. He advised that the aircraft was returned to service and there has been no report of a fuel gauge defect.

The aircraft's fuel selector valve had LEFT, OFF and RIGHT positions. The pilot said that, during the pre-flight cockpit checks for both the preceding flight and the occurrence flight, he had checked that the fuel selector was positioned to a fuel tank, but did not realise that it was positioned to the tank containing only reserve fuel.

The Cessna 207 `engine failure during flight (restart procedures) checklist' in the operations manual was similar to the corresponding procedure produced by the aircraft manufacturer. Importantly, both identified the need to use the auxiliary fuel pump only briefly. However, the pilot said that he had applied a memorised generic engine failure procedure that he had learnt in initial flight training. That procedure did not address specific use of the auxiliary fuel pump. The pilot said that, had there been more time after the engine failure, he would have referred to the copy of the operations manual checklist in the aircraft.

Information provided by the operator indicated that, one week prior to the occurrence, the pilot's induction training had included discussion of engine failure procedures based on a generic procedure similar to that used by the pilot. That training did not include the Cessna 207 `engine failure during flight (restart procedures) checklist' in the operations manual, or in-flight simulated engine failures.

The chief pilot reported that the operator's pilots were required to apply whatever normal and emergency/abnormal procedures they had learnt during early training. The chief pilot stated that: `Once learnt, I believe these checks stand a pilot in good stead for their entire flying career in GA [general aviation] and cannot see any reason to change that approach.' The chief pilot added that: `… all pilots are told when time permits to use the supplied check lists in an emergency.'

The ATSB recently completed an investigation into an engine failure involving a similar aircraft type (Cessna 206, ATSB report 200402049). Although there was fuel on board and no identified aircraft defects, the engine did not restart. The four occupants were seriously injured during the subsequent forced landing. The investigation found that the in-flight engine restart procedures published by the aircraft manufacturer were not followed.

The descriptions of the loss of engine power and the subsequent engine surging were consistent with fuel starvation, a situation where the fuel to the engine is interrupted, although there is adequate fuel on board the aircraft.

Although the left high-pressure fuel pump failed to deliver the required pressure and fuel flow and was found leaking during subsequent testing, it would have had little effect on the development of the occurrence and its defect may have occurred during the accident sequence.

The pilot reported that he had selected inboard tanks for the flight. The investigation was unable to reconcile the pilot's reported recollection of inboard tank selection and the evidence of the remaining fuel quantities in the inboard tanks.

History of the flight

The Piper Aircraft Corporation PA-31-350 Navajo Chieftain, registered VH-UBC, departed Albury on a charter flight with a pilot and six passengers on board. About 5 minutes into the flight, as the aircraft climbed through approximately 5,000 ft, the pilot reported that the right fuel flow light illuminated. The pilot moved the right engine mixture control lever to full rich and advised the Albury Tower controller that he was returning to Albury. A short time later, the right engine started surging. The pilot reported that he changed the right fuel selector from the inboard to the outboard tank selection, although he was aware that there was only a small quantity of fuel in that tank. The engine continued to surge and he reselected the inboard tank. The pilot reported that he did not shut down the engine and feather the propeller because he thought the engine was producing some power.

The pilot reported that approximately a minute after the onset of the right engine problem, the left fuel flow light illuminated and the left engine also started surging. He advised the controller that he was diverting to Holbrook. The pilot found a break in the clouds and descended the aircraft, maintaining visual contact with the ground. On levelling out after the descent through cloud, he reported that the engines operated smoothly, but at reduced power. He reported that he maintained blue line speed for a short time, before power reduced to a level which would not allow altitude to be maintained. During the descent, the pilot opened the crossfeed valve and checked that all fuel pumps were on, mixture controls were rich and the inboard tanks selected. Unable to restore power, the pilot decided to make an emergency landing in an open field below the aircraft. Before landing, the pilot extended the flaps and the landing gear and instructed the passengers to prepare for an emergency landing.

The aircraft contacted the ground with its right wingtip and slewed for approximately 93 metres while rotating almost 180 degrees to the right. The aircraft was substantially damaged, but there was no fire. Neither the pilot nor the passengers sustained any injuries. The pilot reported that before exiting the aircraft he switched off the fuel pumps, magnetos and master switches.

Weather

The weather at Albury and the surrounding area was overcast with low cloud and fog patches. Rain and isolated thunderstorms were forecast for the area. Moderate icing was forecast above 10,000 feet.

Pilot qualification

The pilot held a Commercial Pilot Licence (Aeroplane) with a Multi-engine Command Instrument Rating and was appropriately endorsed on the aircraft type. He held a valid Class 1 medical. On 4 August 2003 he satisfactorily completed a type proficiency check on the Chieftain aircraft. Although not a training and checking requirement for charter flights, the operator additionally stipulated this check for its pilots.

Aircraft

The aircraft was owned by a locally based company that used it to transport its employees between numerous production facilities and was operated by an Albury based charter and training operator on their behalf.

The aircraft was maintained in accordance with the maintenance requirements applicable at that time and had a valid Maintenance Release. It had flown approximately 50 hours since the last maintenance release (periodic) inspection. There were no outstanding maintenance issues at the time of the accident.

Fuel status

The aircraft had flown during the previous day, returning to Albury late that afternoon. The pilot who flew the aircraft that day reported that the aircraft and its systems operated normally. He refuelled the aircraft for the next day's flying, filling only the inboard tanks. No fuel was added to the outboard tanks and the pilot estimated that about 25 to 35 litres remained in each outboard tank.

The rostered pilot reported that, on the morning of the occurrence, he carried out a preflight check during which he visually inspected the fuel tank contents. The pilot reported that he found both inboard tanks full, but could not see any fuel in the outboard tanks. In accordance with the operator's practice, the pilot started and warmed the engines so that the flight could proceed without delay when the passengers arrived.

The `Before starting engine' and `Before take-off' checklist procedures required the pilot to check that the fuel selector valves were selected to INBOARD tanks. Both the manufacturer's and the operator's `Before taxiing' checklist procedures then required the pilot to check the fuel selector at each detented position. The operator reported that pilots were encouraged to check the operation of the fuel selector valves in all detented positions during the engine warm up run. The pilot reported that in order to conserve the fuel in the inboard tanks for the trip, he preferred to warm the engines using the fuel from the outboard tanks.

The departure had been delayed due to fog at the destination. The flight commenced approximately two hours later than planned, when the fog cleared. The pilot reported that he carried out another engine warm up with the passengers aboard and had checked the INBOARD tanks selection before take-off.

Fuel system

The aircraft fuel system consisted of four fuel cells, two in each wing, and had a total capacity of 734 litres, of which 690 litres were useable. It was also fitted with two long-range nacelle tanks that were not used on this flight. The inboard tanks each had a capacity of 212 litres and each of the outboard tanks 155 litres. The tanks were a bladder type and were located between the main and the rear wing spars. The filler caps were located at the outboard end of each tank. The slenderness of the tanks and the wing dihedral resulted in the fuel accumulating at the inboard end of each tank. That meant that unless the tank was full, or nearly full, it was not possible to assess the quantity of fuel remaining in the tank by visual inspection or by dipping through the filler cap opening.

The left and the right wing fuel systems were independent. Two fuel selector valves, one for each wing's fuel system, allowed the pilot to select either OUTBOARD, OFF or INBOARD positions. When a tank was selected, the fuel was fed to the respective engine system. A crossfeed line with a crossfeed valve was the only interconnection between the two wing fuel systems. The crossfeed valve is normally closed.

Wreckage Examination and Component Testing

The aircraft sustained substantial damage during the emergency landing. The right wing was damaged, the landing gear was torn off and both propellers damaged. Damage to the blades of both propellers was almost identical and was consistent with them rotating at impact. Calculations based on an aircraft speed of about 110 kts, as reported by the pilot, and propeller blade slash marks at the initial point of impact, indicated that both propellers were rotating at approximately 1,830 RPM at impact.

When visually inspected through the filler caps shortly after the accident, both inboard tanks were full, but no fuel could be seen in the outboard tanks. The investigation determined that there were 210 to 211 litres of fuel in each inboard tank. The right outboard tank contained approximately 25 litres and the left outboard tank approximately 1 litre of fuel.

Detailed examination of the tanks and the fuel system found no evidence of flow restriction or the presence of any foreign material inside the system. Fuel samples taken from the aircraft were tested and found to comply with the respective fuel specification. The fuel was of the correct type and grade for the aircraft.

Both engines were removed from the aircraft. When tested, they operated normally in accordance with the manufacturer's test schedule. There was no evidence of any defect that would have accounted for the reported malfunction.

The fuel system and its components were tested in situ, and found to operate normally. The selector valves and the pumps were removed and tested. Operation of all but the left high-pressure fuel pump was normal.

The left high-pressure fuel pump failed to deliver the required pressure and fuel flow and was found to leak at the rate of about 1/4 litre per minute. The test facility specialist reported that the possibility of the fault resulting from damage during the accident could not be excluded.

There was no evidence of any other abnormality of the individual fuel system components and controls.

Fuel consumption

Calculated fuel consumption, based on the manufacturer's Take Off and Climb performance charts, determined that from the time the aircraft commenced take-off to its emergency landing, approximately 32 litres of fuel would have been consumed. In addition, 12 litres of fuel was estimated to have been used during the engine warm ups and taxiing.

EXECUTIVE SUMMARY

On 11 August 2003, at about 1535 Western Standard Time, a Cessna Aircraft Company 404 Titan (C404) aircraft, registered VH-ANV, took off from runway 24 right (24R) at Jandakot Airport, WA. One pilot and five passengers were on board the aircraft. The flight was being conducted in the aerial work category, under the instrument flight rules.

Shortly after the aircraft became airborne, while still over the runway, the pilot recognised symptoms that he associated with a failure of the right engine and elected to continue the takeoff. The pilot retracted the landing gear, selected the wing flaps to the up position and feathered the propeller of the right engine.

The pilot later reported that he was concerned about clearing a residential area and obstructions along the flight path ahead, including high-voltage powerlines crossing the aircraft's flight path 2,400 m beyond the runway. The aircraft was approximately 450 m beyond the upwind threshold of runway 24R when the pilot initiated a series of left turns. Analysis of radar records indicated that during the turns, the airspeed of the aircraft reduced significantly below the airspeed required for optimum single-engine performance.

The pilot transmitted to the aerodrome controller that he was returning for a landing and indicated an intention to land on runway 30. However, the airspeed decayed during the subsequent manoeuvring such that he was unable to safely complete the approach to that runway. The pilot was unable to maintain altitude and the aircraft descended into an area of scrub-type terrain, moderately populated with trees. During the impact sequence at about 1537, the outboard portion of the left wing collided with a tree trunk and was sheared off. A significant quantity of fuel was spilled from the wing's fuel tank and ignited. An intense post-impact fire broke out in the vicinity of the wreckage and destroyed the aircraft.

Four passengers and the pilot vacated the aircraft, but sustained serious burns in the process. One of those passengers died from those injuries 85 days after the accident. A fifth passenger did not survive the post-impact fire.

The investigation assessed that the aircraft was below its maximum permitted take-off weight and within centre of gravity limits at the time of the accident. Analysis of radar data indicated that the aircraft was operating significantly below the optimum speed for maximum single-engine climb performance for most of the flight.

A number of factors affect an aircraft's one-engine inoperative performance, including any variation from the airspeed to achieve the one-engine inoperative best rate of climb, control inputs made by the pilot to manage the situation and the effect of manoeuvring/turning the aircraft. One-engine inoperative climb performance would have significantly reduced during the turns, with a loss of at least 25 per cent during a 10 degree angle of bank turn, 50 per cent during a 20 degree angle of bank turn and more than 90 per cent had there been a 30 degree angle of bank turn.

Examination of the right engine revealed a material anomaly with the sleeve bearing from the engine-driven fuel pump. That bearing exhibited evidence of localised adhesive wear (galling) that had restricted the rotation of the pump spindle shaft. The bearing had previously been replaced during the last engine overhaul. Analysis of the bearing revealed that it had been manufactured from material that possessed inferior galling resistance when compared with bearings from similar pumps. The investigation concluded that the specified material for the replacement sleeve bearing was inadequate with respect to its galling resistance. High torsional loads between the spindle shaft and the sleeve bearing had caused the pump's drive shaft to shear at a critical phase of flight. Associated with a loss of drive to the pump shaft was a reduction in fuel pressure, which was insufficient to sustain operation of the engine at take-off power.

Following the occurrence, the operator modified other C404 aircraft in its fleet to incorporate a warning light to indicate low fuel pressure. The ATSB has previously issued three recommendations (see ATSB report BO/200105618) relevant to pilot training for engine-out operations in multi-engine aircraft. Those recommendations are also relevant to the circumstances of this occurrence.

Records from the Fire and Emergency Services Authority of Western Australia (FESA) indicated that the first responding appliances reached the Jandakot Airport emergency gate, about 1,500 m from the accident site, at 1551:52, about 12.5 minutes after being notified by the police. The fire fighting vehicles were not able to track direct to the accident site and had to negotiate runways and bush tracks. The FESA records indicated that the first information from the accident site was received at 1558:28, which stated 'MT is tackling the fire, some persons are out, some persons are missing.'

Following an occurrence at Bankstown Airport in November 2003, the ATSB conducted an investigation at the direction of the Minister for Transport and Regional Services to '…investigate the effectiveness of the fire fighting arrangements for Bankstown Airport as they affected transport safety…'. Bankstown Airport is a General Aviation Aerodrome Procedure (GAAP) aerodrome that had similar provisions for aerodrome rescue and fire fighting services (ARFFS) to Jandakot Airport at the time of the occurrence involving ANV. The ATSB report (200305496) on that investigation is available on the ATSB website.

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