New Zealand

The following findings were identified:
- The pilot did not make the necessary left turn during the take-off roll to align with the strip centreline, so the aeroplane continued the take-off roll in a straight line.
- The right-rear undercarriage struck uneven ground with sufficient force to break the undercarriage mounting brackets and dislodge the undercarriage assembly from the aeroplane.
- The right main undercarriage subsequently struck the right flap, resulting in a partial dislocation of the flap. This very likely resulted in the aeroplane becoming uncontrollable.
- The pilot was about as likely as not to have been incapacitated early in the take-off roll.

Conclusions
3.1 The aircraft struck six 110 kV high voltage power lines.
3.2 The pilot likely experienced inattentional blindness, in that the pilot’s attention was likely engaged on the other aircraft and thus the pilot failed to perceive the visual stimuli.
3.3 The pilot was appropriately rated and licensed to conduct the flight.
3.4 Research has shown that striking a wire that the pilot was aware of usually occurred because something changed, such as a last minute change of plan.
3.5 The pilot elected to change the plan at the last minute and detour during the positioning flight to an area where a pilot from the same operator was also conducting aerial topdressing.
3.6 The pilot did not conduct a hazard briefing for the area about to be flown and thus did not afford himself the most accurate and well informed mental model of the area the pilot elected to operate in.
3.7 Several human factors likely influenced the pilot’s decision-making and risk perception leading to the decision to change the original plan and deviate from the minimum heights as stipulated by CAR 91.311 and operators SOPs.
3.8 The safety investigation did not identify any mechanical defects which may have contributed to the accident.
3.9 The accident was not survivable.

The following findings were identified:
- The first compressor turbine blade failed after a fatigue crack, which had begun at the trailing edge, propagated towards the leading edge. The blade finally fractured in tensile overload. The separated blade fragment caused other blades to fracture and the engine to stop.
- The fatigue crack in the trailing edge of the blade was likely initiated by the trailing edge radius having been below the specification for a new blade.
- The P&WC Repair Requirement Document 725009-SRR-001, at the time the blades were overhauled, had generic requirements for trailing edge thickness inspections but did not specify a minimum measurement for the trailing edge radius.
- The higher engine power settings used by the operator since August 2014 were within the flight manual limits. Therefore it was unlikely that the operator’s engine handling policy contributed to the engine failure.
- The operator had maintained the engine in accordance with an approved, alternative maintenance programme, but the registration of the engine into that programme had not been completed. The administrative oversight did not affect the reliability of the engine or contribute to the blade failure.
- It was likely that the maintenance provider had not followed fully the engine manufacturer’s recommended procedure for inspecting the compressor turbine blades. It could not be determined whether the crack might have been present, and potentially detectable, at the most recent borescope inspection.
- The operator had not equipped its pilots with flotation devices to cover the possibility of a ditching or an emergency bale-out over or near water.
- The pilot had demonstrated that he was competent and he had the required ratings. However, it was likely that the operator’s training of the pilot in emergency procedures was inadequate. This contributed to the pilot making a hasty exit from the aeroplane that jeopardized others.

Loss of height and hard landing due to windshear on short final.

Conclusions
- The pilot was appropriately licensed and held a valid medical certificate.
- The aircraft had been appropriately maintained and no technical discrepancy was discovered that could have contributed to the accident.
- It is likely that, during a climbing turn, the pilot inadvertently allowed an aerodynamic stall to occur at which point the aircraft suddenly departed controlled flight.
- No emergency jettison of the hopper contents was attempted.
- The height above the ground, was insufficient for the pilot to perform a successful recovery once the departure from controlled flight had fully developed.
- The pilot’s lack of experience with agricultural operations and relative unfamiliarity with the aircraft type could not be eliminated as having a bearing on the accident.

Findings:
- There were no technical defects identified that may have contributed to the accident and the aeroplane was considered controllable during the take-off roll, with the engine able to deliver power during the short flight.
- The aeroplane’s centre of gravity was at least 0.122m rear of the maximum permissible limit, which created a tendency for the nose to pitch up. The most likely reason for the crash was the aeroplane being excessively out of balance. In addition, the aeroplane probably became airborne early and at too low an airspeed to prevent uncontrollable nose-up pitch.
- The aeroplane reached a pitch angle that would have made it highly improbable for the unrestrained parachutists to prevent themselves sliding back towards the tail. Any shift in weight rearward would have made the aeroplane 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 aeroplane and was limited in its usefulness to the aeroplane owner for calculating weight and balance.
- Regardless of the procedural issues with the project to modify ZK-EUF, the engineering work conducted on ZK-EUF to convert it from agricultural to parachuting operations in the standard category was by all accounts appropriately carried out.
- The weight and balance of the aeroplane, with its centre of gravity at least 0.122m outside the maximum aft limit, would have caused serious handling issues for the pilot 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 which the aeroplane was certified in its previous agricultural role. Had the aeroplane not been out of balance it is considered the excess weight in itself would have been unlikely to cause the accident. Nevertheless, the pilots should have made a full weight and balance calculation before each flight.
- The aeroplane owner and their pilots did not comply with civil aviation rules and did not follow good, sound aviation practice by failing to conduct weight and balance calculations on the aeroplane. This resulted in the aeroplane being routinely flown overweight and outside the aft centre of gravity allowable limit whenever it carried 8 parachutists.
- The empty weight and balance for ZK-EUF was properly recorded in the flight manual, but the stability information in that manual had not been appropriately amended to reflect its new role of a parachute aeroplane. Nevertheless, it was still possible for the aeroplane operator to initially have calculated the weight and balance of the aeroplane for the predicted operational loads before entering the aeroplane into service.
- The aeroplane owner did not comply with civil aviation rules and did not follow good, sound aviation practice when they: used the incorrect amount of fuel reserves; removed the flight manual from the aeroplane; and did not formulate their own standard operating procedures before using the aeroplane for commercial parachuting operations.
- The Director of Civil Aviation delegated the task of assessing and overseeing major modifications to Rule Part 146 design organisations and individual holders of “inspection authorisations”. The delegations did not absolve the Director of his responsibility to monitor compliance with civil aviation rules and guidance.
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- The delegations increased the risk that unless properly managed the CAA could lose control of 2 safety-critical functions: design and inspection. The Director had not appropriately managed that risk with the current oversight programme.
- The CAA had adhered strictly to its normal practice and was acting in accordance with civil aviation rules when approving the change in airworthiness category from special to standard. However, knowing the scope, size and complexity of the modifications required to change ZK-EUF from an agricultural to a parachuting aeroplane, it should have had greater participation in the process to help ensure there were no safety implications.
- There was a flaw in the regulatory system that allowed an engineering company undertaking major modification work on an aircraft to have little or no CAA involvement by using an internal or contracted design delegation holder and a person with the inspection authorisation to oversee and sign off the work.
- The level of parachuting activity in New Zealand warranted a stronger level of regulatory oversight than had been applied in recent years.
- The CAA’s oversight and surveillance of commercial parachuting were not adequate to ensure that operators were functioning in a safe manner.
- The CAA had mechanisms through the Director’s powers under the Civil Aviation Act and his designated powers under the HSE Act to effectively regulate the parachuting industry pending the introduction of Rule Part 115.
- An alcohol and drug testing regime needs to be initiated for persons performing activities critical to flight safety, to detect and deter the use of performance-impairing substances.
- In this case the impact was not survivable and the passengers wearing safety restraints would not have prevented their deaths, but in other circumstances the wearing of safety restraints might reduce injuries and save lives.
- Safety harnesses or restraints would help to prevent passengers sliding rearward and altering the centre of gravity of the aircraft. It could not be established if this was a factor in this accident.