What happened
On 27 May 2004, a Glaser-Dirks DG-400, registration G-BPIN, was conducting a private cross-country flight from Lasham Airfield. After departing under power, the pilot reached an altitude of 2,000 feet, at which point the engine was shut down and retracted into the fuselage to allow for gliding flight toward Swindon.
During the return glide to Lasham, the aircraft's altitude dropped below a safe glidepath for the airfield. After failing to locate sufficient lift, the pilot attempted to restart the engine to facilitate a return to the airfield. However, upon extending the engine and pressing the start button, the propeller failed to rotate and the engine did not ignite. Because of the low altitude, the pilot focused on executing a landing in a pre-selected field rather than troubleshooting the mechanical issue.
The aircraft struck the ground heavily, resulting in the partial collapse of the main landing gear and significant downward flexing of the wings. As the aircraft moved through the field, the starboard wing made contact with vegetation, causing the aircraft to slew to the right and resulting in damage to the wing.
The investigation
The investigation focused on why the engine failed to restart and the factors contributing to the heavy landing. The pilot noted that there were no injuries to the crew. The investigation examined the engine extension mechanism and the electrical circuit involving the interlock microswitch.
Findings
- The engine failed to start because the starter motor was not receiving power.
- It is believed that the engine may not have been fully extended or the extend/retrol switch may have been inadvertently moved to the retract position.
- If the engine was not properly seated, the interlock microswitch would have prevented the starter motor from energising.
- The aircraft's handling and performance were degraded because the engine was extended but not running, which contributed to the heavy landing.