Accident
Shortly after takeoff from Fox Glacier aerodrome, while climbing, the aircraft stalled and crashed in flames in a paddock near the airfield. All nine occupants, the pilot and eight skydivers, were killed.
Investigation
The investigation revealed that the new owner and operator of the aircraft had not completed any weight and balance calculations before it entered service, nor at any time before the accident. As a result, the aircraft was being flown outside its loading limits every time it carried a full load of eight parachutists. On the accident flight, the center of gravity of the aircraft was well rear of its aft limit, and it became airborne at too low a speed to be controllable. The pilot was unable to regain control, and the aircraft continued to pitch up, then rolled left before striking the ground nearly vertically.
Findings
No technical defects were identified that may have contributed to the accident, and the aircraft was considered controllable during the takeoff roll, with the engine able to deliver power. The aircraft's center of gravity was at least 0.122 meters rear of the maximum permissible limit, creating a tendency for the nose to pitch up. The most likely reason for the crash was the aircraft being excessively out of balance. In addition, the aircraft probably became airborne early and at too low an airspeed to prevent uncontrollable nose-up pitch. The aircraft reached a pitch angle that would have made it highly improbable for the unrestrained parachutists to prevent themselves sliding back toward the tail. Any shift in weight rearward would have made the aircraft more unstable.
The engineering company that modified ZK-EUF for parachuting operations did not follow proper processes required by civil aviation rules and guidance. Two of the modifications had been approved for a different aircraft type, one modification belonged to another design holder, and a fourth was not referred to in the aircraft maintenance logbook. The flight manual for ZK-EUF had not been updated to reflect the new role of the aircraft and was limited in its usefulness for calculating weight and balance. Regardless of the procedural issues, the engineering work conducted to convert ZK-EUF from agricultural to parachuting operations was appropriately carried out.
The weight and balance of the aircraft, with its center of gravity at least 0.122 meters outside the maximum aft limit, would have caused serious handling issues and was the most significant factor contributing to the accident. ZK-EUF was 17 kg over its maximum permissible weight on the accident flight but was still 242 kg lighter than the maximum all-up weight for its previous agricultural role. Had the aircraft not been out of balance, the excess weight alone would have been unlikely to cause the accident. Nevertheless, pilots should have made a full weight and balance calculation before each flight.
The aircraft owner and their pilots did not comply with civil aviation rules and did not follow good aviation practice by failing to conduct weight and balance calculations, resulting in the aircraft being routinely flown overweight and outside the aft center of gravity limit whenever it carried eight parachutists.
The empty weight and balance for ZK-EUF was properly recorded in the flight manual, but the stability information had not been amended for its new role. However, it was still possible for the operator to initially calculate weight and balance for predicted operational loads. The aircraft owner did not comply with civil aviation rules when using incorrect fuel reserves, removing the flight manual, and not formulating standard operating procedures before commercial parachuting operations.
The Director of Civil Aviation delegated assessment and oversight of major modifications to design organizations and inspection authorizations, but these delegations did not absolve the Director of responsibility to monitor compliance. The delegations increased the risk that the CAA could lose control of design and inspection functions unless properly managed. The Director had not managed that risk with the current oversight program. The CAA had adhered to normal practice when approving the change in airworthiness category but should have had greater participation given the scope of modifications. There was a flaw in the regulatory system allowing an engineering company to undertake major modifications with little CAA involvement. The level of parachuting activity in New Zealand warranted stronger regulatory oversight. The CAA's oversight and surveillance of commercial parachuting were not adequate to ensure safe operation. The CAA had mechanisms to regulate the parachuting industry pending new rules. An alcohol and drug testing regime was recommended for persons performing activities critical to flight safety. The impact was not survivable, and safety restraints would not have prevented deaths in this case, but in other circumstances might reduce injuries and save lives. Safety harnesses could help prevent passengers sliding rearward and altering the center of gravity, but it could not be established if this was a factor.