What happened
On 7 January 2014, a Diamond DA 42 Twin Star, registration G-CTCH, was conducting a training flight at Exeter Airport, Devon. Following a successful landing by a student pilot, the instructor decided to initiate a go-around procedure. While attempting to retract the flaps for the climb, the instructor accidentally moved the landing gear lever to the up position.
Although the instructor immediately corrected the lever position, the right main landing gear had already unlocked and collapsed while the aircraft was traveling at approximately 60 kt. This caused the aircraft to yaw to the right and veer off the runway onto the grass. The incident resulted in no injuries to the two crew members or the single passenger on board. The aircraft sustained damage to the right wing tip, the right aileron, the tail skid, and the propeller.
The investigation
The investigation focused on why the landing gear was able to retract while the aircraft was still on the ground. The Diamond DA 42 Twin Star is equipped with a weight-on-wheels switch located on the left oleo strut, designed to prevent gear retraction during ground operations.
Investigators determined that at the time of the error, the aircraft was experiencing a crosswind from the left. Combined with the configuration of the landing flaps, this likely caused a reduction in pressure on the left side of the aircraft. Consequently, the weight-on-wheels switch was not engaged, allowing the gear mechanism to be activated.