What happened
On 6 December 2002, a Piper PA-31 Navajo, registration G-FILL, was preparing for departure from a private grass airstrip located near Peterborough (Milton). During the takeoff roll, the pilot applied power, which caused the aircraft to swing toward the left side of the runway.
In an attempt to maintain the centerline, the pilot reduced engine power and applied right rudder pedal nose wheel steering. As the pilot increased the steering input to counteract the leftward movement, the aircraft instead turned sharply to the right. This resulted in a skid across the grass surface, with the aircraft rotating more than 90 degrees and reaching a speed of roughly 20 knots.
Despite the pilot closing both throttles, the aircraft departed the runway and entered an adjacent ploughed field. The impact caused the left landing gear to sink into the soft ground, leading the left propeller to strike the earth and stop abruptly. The right propeller also made contact with the ground but remained in motion. There were no injuries to the pilot.
The investigation
The investigation focused on the aircraft's behavior during the application of power and the condition of the airfield. The surface of the grass runway was noted to be soft and wet following recent rainfall. The investigation examined the pilot's control inputs, specifically the use of nose wheel steering to correct the initial leftward swing.
Findings
- The primary factor in the loss of control was the abrupt application of power, which induced a leftward swing that the pilot could not effectively counteract.
- The airfield surface was soft and wet due to recent rain, contributing to the difficulty in maintaining directional stability.
- The pilot's decision to increase nose wheel steering input contributed to the subsequent sharp rightward turn and subsequent excursion into the ploughed field.