Executive summary
ZK-FKF was the second in a loose formation of three microlight aircraft which had taken off from Pikes Point Aerodrome, to fly to Raglan. While the formation was flying over the Manukau Harbour, parallel to the north shore, the aircraft was seen to dutch roll, then pitch nose-down. The right wing folded at about one-third span, and the aircraft fell into the sea, killing the pilot.
Similarities between the structural damage of ZK-FKF and other Pterodactyl Ascender microlights involved in mid-air breakups suggested design deficiencies. Video recordings of two such accidents demonstrated that the wings fluttered following an uncontrollable pitch down, the flutter forces resulting in the subsequent breakup.
Analysis indicated an insufficient reserve of pitch stability when the aircraft was flown at the upper end of its speed range, together with other control and structural design shortcomings.
It was recommended that the type's Permit to Fly be withdrawn.
Related Recommendations
When a Permit to Fly is sought for an aircraft which will be the first of type in New Zealand, a more detailed search of the literature be made with a view to discovering the type's accident record.
Require the owners of Pterodactyl Ascender II + 2 aircraft to remove the second seat and associated structure.
Require the owners of Pterodactyl Ascender II + 2 aircraft to remove the second seat and associated structure.
Make interim restrictions on all Pterodactyl Ascender aircraft permanent. [The interim restrictions were: • Vne limited to 45 mph; • Flight in calm conditions only; • Restricted to local flying.]
Withdraw the Permit-to-Fly from Pterodactyl Ascender II + 2 microlight aircraft.
Advise members that these aircraft should be flown only by experienced pilots.