The pilot was tasked to convey six passengers from Brisbane to
Miamba, about 165 NM WNW of Brisbane, and return. The aircraft was
parked at Archerfield and the passengers were to be picked up at
Brisbane Airport.
The aircraft operator had no formal system of recording the
amount of fuel remaining in the aircraft at the end of each flight.
Normally, the fuel state was discussed between the pilots of the
previous and next flights. In this instance, however, the pilot did
not speak to the person who last flew the aircraft. The pilot said
that it was his practice to use the fuel gauges and the fuel gauge
calibration chart to determine the amount of fuel in the
aircraft.
The weather forecast obtained by the pilot indicated the 7,000
ft wind as 110 degrees at 15 kts, and the 5,000 ft wind as 120
degrees at 20 kts. The pilot calculated the following flight times
and fuel requirements for the intended flights, assuming a fuel
consumption rate of 140 lt per hour:
Archerfield - Brisbane 5 mins, 27 lt
Brisbane - Miamba 59 mins, 174 lt
Miamba - Brisbane 59 mins, 174 lt
Total 123 mins, 375 lt
Before the flight, the pilot obtained information about the
destination airstrip and decided to have the aircraft refuelled to
full main tanks (415 lt). The fuel gauges for the auxiliary tanks
were indicating half full. Using the lesser of the aircraft flight
manual and the fuel calibration card figures, the pilot assessed
that the auxiliary tanks contained 147 lt. From this information,
he calculated that the aircraft contained 562 lt of fuel -
sufficient for about 4 hours of flight.
Because of air traffic control requirements and the prevailing
weather conditions, the flight from Archerfield to Brisbane took
about 30 minutes.
During the flight to Miamba, the pilot selected the auxiliary
tanks for a period during cruise at 8,000 ft, but did not record
the times when these selections were made. Flight duration was
about 66 mins.
At Miamba, the pilot estimated (from the fuel gauges) that there
was 280 lt fuel remaining for the return flight to Brisbane. At top
of climb (7,000 ft) he again selected the auxiliary tanks. Because
the gauge indications reduced faster than he anticipated towards
empty, he allowed the auxiliary tanks to empty before re-selecting
the main tanks. The pilot said that the fuel quantity gauges
indicated about 1/8 when the auxiliary tanks were empty. Because of
headwinds, the pilot descended to 5,000 ft to try to achieve a
higher ground speed but to little effect. At that altitude, the
aircraft was in cloud.
At about 30 nm from Brisbane, with the gauges indicating about
1/8, the pilot became concerned that there might not be sufficient
fuel to complete the flight to Brisbane. He descended to 4,000 ft,
again seeking a better ground speed. The pilot then elected to
divert to Archerfield (which was closer) and told air traffic
control that he did not wish to descend further until close to
Archerfield. Shortly after being cleared to turn towards
Archerfield, the left engine surged and then ceased operating. The
pilot feathered the propeller and informed air traffic control that
he required an immediate landing at Amberley. He did not declare an
emergency.
Soon after the left engine failed, the aircraft flew clear of
cloud and the pilot saw Amberley aerodrome. He conducted a
straight-in approach to runway 15 at Amberley. He manually extended
the landing gear with assistance from the passenger in the right
control seat. The aircraft touched down about 5,000 ft along the
runway and the pilot deliberately steered the aircraft off the
runway edge on to grass late in the landing roll. There was no
damage to the aircraft. The flight from Miamba had taken about 84
minutes. After refuelling, the engines operated normally.
Investigation revealed that the aircraft actually contained
about 477 lt on start-up at Archerfield - 85 lt less than the pilot
believed. That included 220 lt remaining from the previous flight,
and 257 lt added during refuel. The aircraft operator said that his
company used a rate of 150 lt per hour for flight planning
purposes. Based on that figure, there was sufficient fuel on board
the aircraft for about 190 minutes flight. From the total flight
time of about 180 minutes, the aircraft had achieved an actual fuel
usage rate of about153 lt per hour (allowing about 30 minutes
ground operating time), close to the planning figure used by the
operator. It is logical to conclude, therefore, that the engines
performed normally during the flight, and that the fuel supply to
the left engine was exhausted, causing it to cease operating. It is
likely that the fuel supply to the right engine would also have
been exhausted within a few minutes if the pilot had not shut the
engine down.
The pilot said that, based on the handling notes for the
aircraft, 126 lt fuel per hour would be consumed at 65 per cent
engine power (31 inches MAP and 2,200 rpm). He had used a rate of
140 lt per hour in planning for the flight, which he considered
more than adequate. Although the pilot's aeronautical experience
was significant, over 90 percent of it was as a flying instructor
on single engine aircraft. The pilot had little experience in
charter operations. His experience on the aircraft type was also
low.