What happened
On 22 May 1998, a Piper PA-28-151, registration G-BCTA, was conducting a private flight from Le Touquet to Manston. During the transit, the pilot observed a low voltage warning light. Despite reducing electrical loads and briefly applying full power, the warning light remained illuminated, though the ammeter reading stayed within normal parameters.
While navigating towards the Dover VOR using the autopilot, the pilot disengaged the system to initiate a descending turn onto a northerly heading. Shortly after this maneuver, the pilot and passenger discovered that the control yoke movement was severely restricted, specifically preventing any movement to the right from the neutral position. Although the rudder and elevators remained functional, the physical limitation of the yoke prompted the decision to perform a precautionary landing in a nearby field near Ripple Village.
As the aircraft approached the landing site, the pilot encountered unexpected obstacles, including houses and power lines, which forced a touchdown point further into the field than planned. The pilot had already set the mixture to idle cut-off before realizing the field featured a significant upward slope and a mature hedge. Upon touchdown, the aircraft drifted approximately 45 degrees before striking a hedge and bank, which caused the left wing to separate from the fuselage. There were no fatalities and only minor injuries to the pilot; the passenger was uninjured.
The investigation
Investigators examined the wreckage and consulted with the aircraft's maintenance company's Chief Engineer. While the engineer found no visible evidence of a mechanical failure within the primary flying control system to explain the restriction, the AAIB focused their investigation on the autopilot components. These units were sent to an overhaul agency for specialized functional testing, specifically looking at the behavior of the controls during the disengagement process.