A screwdriver found among the wreckage may have caused a Yak-52 aircraft to crash into a Feilding park, killing the two occupants, air crash investigators say.
Civil Aviation Authority (CAA) investigators on Thursday said they were following a line of inquiry that the loose screwdriver may have become jammed somewhere and made it impossible to fly the aircraft.
It was too early to conclude that was the cause of the crash on January 23, but the screwdriver find was of grave concern, the investigators said.
"The finding mirrors an accident involving a Yak-52 aircraft in the United Kingdom in 2003, in which two people were killed. In this accident, a stubby-type screwdriver became lodged in the tail of the aircraft affecting its controls," they said.
Pilot Ralph Saxe, 51, of Palmerston North, and passenger Brett Ireland, 50, who had been living in Queensland, were killed when the Yak-52 crashed into the sports field at Timona Park.
Dr Saxe's funeral was held on Thursday.
The Yak-52 was reported to be doing aerobatics before it crashed, and the CAA has contacted all New Zealand Yak-52 owners about the screwdriver find, and is strongly recommending a thorough visual inspection for any foreign objects before aerobatics.
The Yak-52 was a replica of the 1970s Russian two-seater training aircraft.
The investigation into the accident is continuing and it is hoped that a preliminary report will be published within three weeks.