History of the Flight
The pilot of the Cirrus SR20, G-GCDC, planned to perform circuits at Swansea Airport and a short local flight. During pre-flight checks, he discovered that his kneeboard had inadvertently engaged the autopilot heading mode. After repositioning the kneeboard, he continued. The aircraft took off at 1329 hrs for a local flight and subsequently performed three touch-and-go landings on Runway 10. On the fourth approach, the pilot described it as routine, with 100% flap and a speed of 78 KIAS. As the aircraft crossed the runway numbers, the pilot reduced the rate of descent to avoid a known rough area at the intersection with Runway 04/22. The aircraft drifted left, attributed to gusting wind from the right, then rolled left, causing the left main wheel to contact the runway and the aircraft to bounce. The left wingtip also struck the runway. The pilot applied full power to continue the touch-and-go. The aircraft then turned sharply left, rolling to about 45° and adopting a high pitch attitude. The pilot recovered to wings level over Taxiway Bravo at about 20 ft agl, but the aircraft descended, the nosewheel detached after striking a grass verge, the propeller struck the ground, and the aircraft slid into a parked Piper PA-38-112 Tomahawk, G-BLWP. All occupants, wearing full harnesses, were uninjured and exited through the doors. No fuel leak occurred, and the airbags did not deploy.
Aircraft and Autopilot Information
The Cirrus SR20 was fitted with an S-TEC 55X autopilot that could control roll and pitch axes. The autopilot could be engaged at any time, including on the ground, unless system failures were present. When engaged in heading mode, the aircraft would turn to the selected heading. There was no audible alert when this mode engaged. The autopilot could be overridden by control yoke and rudder inputs, and disconnection required pressing the disconnect button on the control yoke.
The parked aircraft, a Piper PA-38-112 Tomahawk (G-BLWP), sustained damage to its right wing.
Recorded Data and Discussion
The Cirrus SR20 was fitted with a Recoverable Data Module, but the last recorded flight was in September 2013. The electronic flight displays recorded data at six-second intervals, but no autopilot information was recoverable. Recorded engine parameters showed rpm increasing from 2,160 to 2,460 during the touch-and-go, then reducing to 1,550 rpm as the aircraft departed left. The last recorded position matched the pilot's account.
The pilot reported that during pre-flight checks, the heading bug was set to north. The inadvertent autopilot engagement during pre-flight was demonstrated to passengers. Two weeks after his initial statement, the pilot raised the possibility that the autopilot had inadvertently engaged during the touchdown, which, with the heading set to north, would have exacerbated the left turn. After the event, the roll trim was found set to left roll. The cause of the initial deviation to the left could not be determined from recorded data; it was considered possibly due to a gust of wind, inadvertent autopilot engagement, or a combination.