Accident Overview
An aerial topdressing operation was underway from a sloping airstrip on a headland near Matakana. The aircraft, registration ZK-CBI, was loaded with 915 kg of granulated superphosphate fertilizer and additional fuel for the first flight of the operation. The pilot had previously inspected the airstrip and requested the farmer to cut saplings at the departure end.
Accident Sequence
The loader driver did not observe the takeoff but later saw a cloud of fertilizer dust beyond the airstrip, indicating that the pilot had jettisoned the load. Shortly after, the driver sighted the aircraft briefly through a gap in trees; it was flying at sowing height on a reciprocal course with a faint fertilizer trail. The aircraft then disappeared, and the driver saw what appeared to be a piece of red paper fluttering to the ground. When the aircraft failed to land, a search was conducted. The wreckage of ZK-CBI was found in dense scrub about 350 meters to the left of the departure end of the airstrip. The pilot, sole occupant, was killed.
Investigation Findings
The investigator determined that the pilot initiated jettison of the load 36 meters before the boundary fence. It was not clear whether the aircraft was still on the ground or airborne at low speed when it collided with a concrete post and wire fence. Two posts had almost completely severed both halves of the "all flying" tailplane (stabilator). The outboard left-hand section was retained only by the trim tab. The outboard part of the right-hand side later detached and was found 150 meters from the crash site.
Despite the tailplane damage, the pilot managed to clear a low ridge and fly over a large basin, completing a 180-degree turn to return to the airstrip. However, before the approach could be completed, the outer part of the right-hand stabilator separated. The aircraft then dived steeply to the ground and was destroyed by the severe impact. No fire broke out. The crash was not survivable.
Reported Findings
The investigation stated that the aircraft was loaded within approved limits. Kikuyu grass on the airstrip caused a significant deterioration in acceleration during takeoff. The aircraft was capable of normal operation before the fence collision. The collision caused critical damage. Approximately one quarter of the total horizontal stabilizer area separated from the aircraft some minutes after the collision, rendering it uncontrollable in pitch and resulting in the dive.