What happened
On 24 October 2001, an Enstrom 280FX, registration G-BSLV, was conducting a private flight near Chesterton Golf Club, Shropshire. The pilot had recently collected the aircraft from a maintenance facility following its annual inspection. During the initial pre-flight inspection, the pilot noted that the throttle felt stiff at mid-travel, though this was resolved with additional force.
After refueling the aircraft, the pilot departed with the intention of returning home. Approximately one minute into the flight, while maintaining an altitude of 300 feet, the engine manifold pressure began to drop. In an attempt to maintain rotor speed, the pilot lowered the collective lever. As level flight became unsustainable, the pilot initiated an autorotation to land in a nearby field. The aircraft touched down gently in a flat area of the field, following a short run-on of approximately 6 feet. While there were no injuries, the tail rotor blades sustained damage to their leading edges after contacting knee-high crops during the landing.
The investigation
Investigators examined the engine's turbocharger system, specifically the linkage between the fuel servo and the wastegate control. This system uses a collapsible link designed to allow throttle operation even if the wastegate seizes. The investigation focused on the mechanism of this link, which utilizes a spring-loaded plunger and a detent to maintain a fixed position.
Upon inspection, it was discovered that the detent had failed, causing the linkage to collapse. This mechanical failure was identified as the reason for the loss of engine power during the flight. While the maintenance organization was unable to identify the specific cause of the detent breaking out, they were able to reset the link and verify that the throttle could function through its full range of motion without further failure.