What happened
On 4 September 2010, a Walter Fletcher aeroplane, registered ZK-EUF, crashed into a field near the runway at Fox Glacier aerodrome. The aircraft was operating as a parachute-drop plane, carrying eight parachutists and a pilot at the time of the accident. During the takeoff roll, the aircraft experienced an uncontrolled pitch-up, followed by a left roll and a dive into the ground. The impact resulted in nine fatalities.
The investigation
The investigation examined the aircraft's recent history and operational procedures. Only three months prior to the accident, the aircraft had been converted from an agricultural role to a parachute-drop role. Investigators found that the modification process was poorly managed, and the Civil Aviation Authority of New Zealand had approved the change without detecting discrepancies in the modification documentation.
Furthermore, the investigation established that the operator had not performed weight and balance calculations for any flights prior to the accident. This meant the aircraft was frequently operated outside of its intended loading limits. While a subsequent review of the evidence indicated that the aircraft was 110 kilograms over its maximum permissible weight, it was still within the maximum all-up weight certified for its previous agricultural use. The engine was found to be delivering power throughout the flight and until the moment of impact, and no specific mechanical defects were identified.
Findings
- The aircraft's centre of gravity was located rearward of the aft limit, estimated to be at least 0.120 metres beyond the flight manual's allowable range.
- The pilots were routinely operating the aircraft without knowledge of the specific weight and balance for their flights, which increased the risk of instability.
- While the rearward centre of gravity alone was not determined to be the sole cause of the crash, it significantly increased the risk of losing control when combined with other adverse factors.
- The investigation could not definitively determine the specific factor that triggered the excessive pitch-up and subsequent stall.