What happened
On March 17, 2017, a Jodel DR 1050, registration HB-SEW, was conducting a flight test for the renewal of a single-engine piston class rating. The flight originated from Speck-Fehraltorf and proceeded to the St. Gallen-Altenrhein Regional Airport.
Upon landing on runway 28, the pilot intended to transition his feet from the rudder pedals to the toe brakes to begin the braking process. However, before the pilot could reposition his feet, the aircraft began to drift to the left. The pilot attempted to correct this with right rudder input, but the aircraft then suddenly yawed to the right and veered sharply off the runway. The aircraft traveled in a tight right-hand turn through the runway edge lights and into the adjacent field, where the left main landing gear collapsed. The aircraft sustained heavy damage, but both occupants remained uninjured.
The investigation
SUST examined the mechanical and operational aspects of the incident. The investigation noted that the aircraft had been modified in 2015 to replace heel brakes with toe brakes. Due to the limited space in the footwell, the pilot must intentionally lift his soles to reach the brake pedals.
Investigators also looked into the steering mechanism of the tailwheel. While wear was found on the steering lever's locking mechanism, which caused the tailwheel to unlock slightly earlier than a new component would, this was not determined to be the primary cause of the loss of control.
Findings
- The pilot was focused on managing lateral corrections using the rudder and did not successfully reposition his feet to the toe brakes in time.
- The examiner/expert also had his feet positioned only on the rudder pedals, meaning neither occupant was applying the brakes to assist in directional control.
- The wheel brakes were not applied to control the aircraft's direction during the rollout, leading to the lateral loss of control.
- The aircraft's design requires a specific foot movement to engage the brakes, which can interrupt continuous directional control during the critical phase between touchdown and reaching taxi speed.