Background
An operator arranged a ship's crew exchange program, transporting 16 persons and baggage from Portland to Essendon and back. Two Piper PA-31-350 aircraft, VH-POC and VH-RNH, were assigned. Prior to departure from Essendon, both pilots prepared flight plans under Instrument Flight Rules, calculating 208 minutes of fuel for the first return flight, including 30 minutes for holding due to forecast thunderstorms. Both aircraft were refueled to capacity, providing 280 minutes endurance.
Flight Planning and Loading
The aircraft departed for Portland without incident, arriving around 14:00. After a break, pilots returned at 15:00 and conducted pre-flight checks. Passengers arrived with significant baggage. Pilots began weighing baggage and recording weights, but due to a light-hearted and confused atmosphere, not all baggage was weighed, the manifest was incomplete, and bags were not individually marked. Baggage was shared between aircraft without weight consideration. In VH-POC, rear cabin baggage was not restrained. Pilots estimated average baggage weight at 20 kg per passenger and assumed standard passenger weight of 77 kg. Each pilot completed a load sheet for eight passengers. For VH-POC, the sheet showed a fuel load of 290 kg and total weight of 3,080 kg, below the maximum 3,178 kg. However, an incorrect operating weight and arithmetic error resulted in an actual weight of 3,256 kg. When embarking, passengers were directed to the aircraft without any grouping effort; nine passengers boarded VH-POC. The pilot did not correct the imbalance.
Takeoff and Engine Failure
The pilot started engines and taxied for Runway 22. Weather conditions were fine: visibility 15 km, temperature 22°C, surface wind from 210-220° magnetic gusting 25-35 knots, with significant turbulence due to a coastal headland. The pilot had previous experience with such conditions. The takeoff run commenced, with full power obtained from both engines. At 95 knots, the aircraft rotated, and after establishing a positive climb rate, the landing gear was retracted. At 60-70 feet, after reducing power to climb setting, the left engine suddenly lost power. Ground witnesses noted slow acceleration and a low climb profile with a right slew; irregular engine noise was heard. The pilot confirmed left engine failure by closing the throttle, but upon reopening noted slight power response and did not shut down or feather. The landing gear audio warning sounded throughout most of the flight, indicating a throttle near closed.
Forced Landing
The aircraft lost height, and with an imminent forced landing, the pilot turned right to avoid the sea. Control was difficult in gusty conditions, but the pilot reduced speed, lowered gear, and landed on undulating, sandy scrub terrain. The landing gear and engines tore off, and the aircraft came to rest after 26 meters. The fuselage broke open near the rear door. Some passengers evacuated without assistance and helped others. A small fire near the left engine ignited at rest, then spread and engulfed the fuselage before the final passenger could be extricated.
Post-Accident Examination
Examination of wreckage was hampered by fire damage. No pre-existing fault was found in recovered components. The left propeller was feathered at impact. The aircraft's weight and center of gravity could not be precisely determined due to destroyed baggage compartments, but evidence indicated weight at least 3,400 kg and center of gravity likely beyond the aft limit. Piper PA-31-350 performance data showed a maximum single-engine climb rate of 220 feet per minute at limit weight (3,178 kg), reduced by about 40% to 134 feet per minute at 3,400 kg. Additional factors like aircraft age, turbulence, and suboptimal airspeed would preclude a positive climb rate.
Probable Cause
The probable cause of the accident was that the aircraft experienced a loss of power from one engine under conditions which precluded a safe continuation of flight. The two most significant conditions were aircraft overloading and turbulence. The nature and cause of the power loss have not been determined.