What happened
On October 10, 2013, a Robin DR400-140B, registration F-GCIM, was performing a local flight at the Granville Mont-Saint-Michel airfield. The flight, operated by a flying club, consisted of a departure from Granville to Avranches Le Val-Saint-Père, followed by a return to the origin.
During the landing on runway 07, the pilot encountered a 15-knot wind from 350 degrees. As the nose wheel made contact with the runway, the aircraft suddenly veered to the left and exited the paved surface. At a low ground speed, the nose gear struck a rabbit burrow, causing the nose gear strut to break and one propeller blade to bend. The aircraft sustained heavy damage.
The investigation
Investigators examined the wreckage and ground tracks, noting that the main wheels touched down 70 meters from the runway threshold. The aircraft traveled approximately 325 meters before coming to a halt, with the trajectory deviating from the centerline about 150 meters after touchdown.
Technical analysis focused on the nose gear locking mechanism. On this specific model of Robin aircraft, the nose wheel automatically locks in the longitudinal axis of the aircraft when the associated shock absorber is not compressed. Unlocking occurs only when the shock absorber is compressed. The investigation also reviewed the pilot's experience, noting that while the pilot was proficient in the DR400-120 model—where braking is achieved via rudder pedals—the F-GCIM utilizes a manual handbrake located on the center console.
Findings
- The nose wheel likely remained locked in the longitudinal axis because the shock absorber was not sufficiently compressed. This was likely caused by the pilot applying excessive rearward pressure on the control column, possibly to maintain the runway centerline during the crosswind landing.
- As the aircraft slowed, the rudder lost effectiveness, and the wind caused the aircraft to weathercock to the left.
- Because the nose wheel was locked and the aircraft was lightened by the pilot's control inputs, the pilot could not prevent the directional deviation.
- The pilot's attempt to correct the excursion via the rudder pedals was ineffective because the F-GCIM requires the use of a manual brake lever. This error was attributed to the pilot's limited experience with this specific aircraft type and the stress of the unexpected excursion.
- While the aircraft's flight manual allows for full flaps during crosswind landings, updated recommendations suggest using only one notch of flaps to maintain higher speeds and better control, despite the increased landing distance.