Fuel starvation involving a Lancair ES, VH-DFH, 22 km north-west of Mansfield (ALA), Victoria, on 18 April 2016

What happened

On 18 April 2016, at about 1030 Eastern Standard Time (EST), a Lancair ES aircraft, registered VH-DFH (DFH), was taxiing to depart from a private airstrip about 22 km NW of Mansfield (ALA), Victoria. The pilot was the only person on board the private flight.

After conducting an engine run-up, the pilot taxied the aircraft to take-off towards the east on the sealed strip. The pilot reported that the engine run-ups, taxi, and take-off were normal. During the initial climb, at about 500 ft, the engine suddenly lost power and the pilot established the aircraft in a glide, reducing the throttle and looked for a suitable forced landing area. Some engine power returned but was very intermittent and the engine was not producing the correct power for the engine control settings.

The pilot advised that conducting a forced landing straight ahead would have involved negotiating houses, trees, livestock, and the unknown nature of the ground surface. They assessed that sufficient height was available to return to the airstrip so commenced a turn to the left.

The pilot lined up with the airstrip landing towards the west. As the pilot considered that the aircraft had good height and speed, the pilot elected to extend the flaps half-way and subsequently extended the flaps to the full down position as the pilot was concerned that the aircraft would overshoot the airstrip.

The aircraft touched down about 25 m before the threshold on a grass area. The aircraft bounced slightly, touching down again on the grass area beside the airstrip. The left wing contacted an electric fence post and came to a stop a further 100 m after the initial touch down point (Figure 1). The pilot exited the aircraft after turning off all the electrical and engine controls. The pilot was not injured and the aircraft had minor damage.

Figure 1: DFH at the accident site

Source: Aircraft owner

Pilot comment

The pilot reported that the aircraft was inspected subsequent to the incident at an aircraft maintenance facility and no defects were found with the aircraft or engine. The maintenance personnel assessed that fuel starvation^[1] was the probable reason for the power loss due to the way the aircraft had been parked on an incline prior to taxi and take-off. The pilot reported that the aircraft has two independent fuel tanks, one in each of the slim line wings. During the pre-flight inspection, the aircraft was situated with the left wing on the downhill side for a little over half an hour. It is believed that the fuel drained away from the fuel pick up toward the wing tip through a one-way flapper valve^[2] reducing the quantity of fuel available in the sump area where the left wing fuel pick up is located. The pilot reported that the left fuel tank had been selected for the taxi and take-off.

The pilot reported that a self-briefing was routinely conducted before each flight for possible emergencies with decision points and suitable emergency landing areas considered.

The pilot indicated that the wind speed was about 10 knots gusting to about 25 knots from the NE which may have contributed to an undershoot of the airstrip.

Safety action

Whether or not the ATSB identifies safety issues in the course of an investigation, relevant organisations may proactively initiate safety action in order to reduce their safety risk. The ATSB has been advised of the following proactive safety action in response to this occurrence.

Aircraft owner

As a result of this occurrence, the aircraft owner has advised the ATSB that they are taking the following safety actions:

The owner is considering installing a placard in the aircraft to remind pilots when the aircraft is parked on an incline to consider which fuel tank to select for take-off.

Safety message

The ATSB booklet Avoidable Accidents No. 3 - Managing partial power loss after take-off in single-engine aircraft is available from the ATSB website and aims to increase awareness among flying instructors and pilots of the issues relating to partial power loss after take-off in single-engine aircraft.

During and after take-off, a partial power loss is three times more likely in today’s light single‑engine aircraft than a complete engine failure. There have been nine fatal accidents from 2000 to 2010 as a result of a response to a partial power loss compared with no fatal accidents where the engine failed completely. Analysis of the occurrences supports the need to raise greater awareness of the hazards associated with partial power loss and to better train pilots for this eventuality.

The booklet highlights the importance of:

• pre-flight decision making and planning for emergencies and abnormal situations for the particular aerodrome including a thorough pre-flight self-brief covering the different emergency scenarios.
• conducting a thorough pre-flight and engine ground run to identify any issues that may lead to an engine failure.
• taking positive action and maintaining aircraft control either when turning back to the aerodrome or conducting a forced landing until on the ground, while being aware of flare energy and aircraft stall speeds.

Further information about the wing fuel tank one-way flapper valve is contained in an article published by the Lancair Owners & Builders Organisation, Fuel system inspection & calibration and is available from their website. The article discusses how the flapper valve prevents fuel from flowing away from the inner most fuel compartment where the engine fuel supply line is located. It also discusses how the small wing dihedral makes the aircraft particularly sensitive to the outward flow of fuel.

Aviation Short Investigations Bulletin- Issue 52

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1. Fuel starvation happens when the fuel supply to the engine(s) is interrupted although there is adequate fuel on board.
2. The flapper valve prevents fuel from sloshing around during normal flight.