A group of pilots had arranged to conduct a fly-in at Clifton,
Queensland. As part of their day's outing, they had also arranged
for a visit to a collection of aircraft at Toowoomba. The accident
pilot was to fly a single-seat RV-3 amateur-built aircraft on
behalf of the aircraft owner. To re-familiarise himself with the
aircraft, the pilot had conducted some local flying at Southport on
the previous day.
Soon after the RV-3 became airborne during the departure from
Southport for Toowoomba, the engine began to run roughly. The pilot
landed the aircraft and operated the engine to clear what he
suspected to be spark plug fouling. The subsequent takeoff was
apparently normal, and the aircraft arrived at Toowoomba without
further incident.
Following the visit to the aircraft collection, the pilots
prepared for departure to Clifton. The pilot of the RV-3 taxied to
the threshold of runway 11 for departure. Witnesses reported that
the takeoff and initial climb were normal until the aircraft
reached a height of about 200 ft, when the engine suddenly lost
power.
The nose-attitude of the aircraft was observed to lower and the
engine subsequently regained power. The aircraft then began a
gentle climb and turned left. Witnesses reported that it appeared
the pilot was attempting to manoeuvre the aircraft to land on the
aerodrome. After the aircraft gained some altitude, the engine
again lost power. The bank angle steepened and the nose-attitude
lowered significantly. The aircraft's wings were then seen to level
and the nose lifted to a near level attitude, however, the aircraft
continued to descend at a high rate until impact on a playing
field. The sides of the cockpit buckled outwards during the impact,
allowing the fuselage behind the pilot to move forward, and the
pilot's shoulder harness to slacken. He was no longer adequately
restrained and received fatal injuries.
The pilot was correctly licensed and qualified to conduct the
flight.
The aircraft was registered as Experimental, and was fitted with
a fuselage fuel tank and a tank in each wing. The fuel selector
valve was positioned to the right wing tank and there were
indications that both wing tanks had contained a significant
quantity of fuel at impact.
Examination of the aircraft found that a fuel line connecting
the fuel filter to the engine-driven pump had a loose connection at
the filter. The carburettor float showed evidence that the
carburettor fuel level had been low during aircraft operation. The
condition of the spark plugs was consistent with operating in a
lean mixture immediately prior to the engine stopping. No other
defects considered likely to have contributed to the accident were
found.
In addition to the engine-driven fuel pump, the aircraft was
fitted with an electrically-powered auxilliary fuel pump. Both
pumps were tested and found to operate normally. The loose fuel
line connection could have allowed air to enter the carburettor.
This may have been prevented had the electric pump been selected
on, as it would have provided fuel pressure to the engine-driven
pump. The investigation could not determine whether the electric
fuel pump had been selected on for the takeoff. The aircraft owner
said that he had never used the electric pump for takeoff.