History of the Flight
The pilot had flown into Ashcroft on the morning of the accident flight. He subsequently walked 50 meters of Runway 27 and assessed the surface as dry and suitable for departure. At approximately 1700 hours, the pilot started the engine, taxied to the undershoot of Runway 27, and carried out power checks. He estimated the surface wind to be 300° at 5-10 knots. Acceleration during the takeoff roll seemed normal with one stage of flap selected.
In accordance with the Pilot's Operating Handbook soft field takeoff technique, the pilot rotated at minimum speed and then held the aircraft in ground effect to achieve a climb speed of 61 knots. Approaching the four-foot-high fence at the end of the runway, the pilot rotated further to the climb attitude. The rear fuselage underside struck the fence, pitching the aircraft nose-down. This caused the nosewheel to strike the ground and collapse. The aircraft subsequently pitched down and came to rest inverted, facing back towards the airfield. The pilot, who was wearing a full harness, switched off the fuel and battery master switch before being dragged from the wreckage by the airfield owner.
Eyewitness Report
An eyewitness observed the takeoff roll. He reported that the wind was light and variable and that during the takeoff run the acceleration appeared slow. He also reported that the aircraft adopted a high nose-up attitude shortly before the accident.
Performance
The pilot had carried out a calculation of the aircraft's takeoff performance incorporating both a factor for grass and the CAA recommended safety factor of 1.33. The pilot calculated that with a 10-knot headwind and at maximum takeoff weight, a distance of 537 meters was required to clear a 50-foot obstacle. He estimated that his actual takeoff weight was 91 pounds less than the maximum allowed. CAA Change Sheet number 4, issue 1 to the Piper PA-38-112 Pilot's Operating Handbook 'Performance Writedown' states: 'Take-off field lengths – Add 5%.' This was not included in the pilot's calculation.
Runway 27 is declared in various flight guides as 550 meters long. This length is based on information provided to the current owner by previous owners. The current owner has informed the AAIB of his intention to re-measure the runway to ensure the accuracy of the distance declared.
Pilot's Assessment
The pilot considered that several factors may have caused the accident. He suggests that the performance of G-OLFC was below that calculated. This may have been due to a lower headwind factor or possibly a dragging brake. He also suggested that the strip may be shorter than allowed for in his calculations. However, the pilot considered it likely that he was concentrating on the approaching fence and misjudged the pull up from level acceleration to climb away.