What happened
On 28 October 2004, a Piper PA-28-151 Warrior, registration G-BDGM, was preparing for departure from Netherthorpe airfield. During the pre-takeoff engine run-up, the pilot observed a significant drop in RPM while testing the magnetos. Believing moisture was affecting the ignition, the pilot leaned the mixture and continued the run-up until the engine appeared to be operating normally.
For the departure, the pilot employed a short-field technique, utilizing two stages of flaps and applying full power while holding the brakes. As the aircraft accelerated down Runway 2ally, the pilot realized that the aircraft would not reach flying speed before the end of the runway. With approximately 150 metres of the marked runway remaining, the pilot attempted to abort the takeoff by retarding the throttle and applying the brakes. Realizing a collision with the airfield boundary was unavoidable, the pilot raised the aircraft nose to cushion the impact. The aircraft briefly became airborne before striking a hedge, resulting in an engine fire that damaged both wings and the landing gear. The pilot sustained light injuries but was able to exit the aircraft and shut off the fuel and battery.
The investigation
The investigation focused on the aircraft's performance capabilities relative to the runway conditions. The airfield's Runway 24 is a grass surface with a 1.9% uphill gradient. While the aircraft's weight was well within limits, the investigation examined how the damp surface and slope affected the required takeoff distance.
Engine inspections were conducted, though the magnetos had been returned to the manufacturer prior to examination. The remaining engine components showed no defects that would explain the initial RPM fluctuations. It could not be definitively determined if the engine was producing its rated power during the takeoff roll.
Findings
- The takeoff attempt was unsuccessful due to insufficient runway length to accommodate the aircraft's performance requirements under the prevailing conditions.
- The combination of a damp grass surface and an uphill gradient significantly increased the required takeoff run.
- Calculations based on CAA safety guidance suggested that the required takeoff distance for the aircraft's weight and conditions should have been substantially higher than the available runway length.
- A reduction in engine performance during the takeoff roll may have contributed to the inability to reach rotation speed.