What happened
On March 22, 2019, a Grob G520 Egrett was performing a maintenance flight from the Mindelheim-Mattsies airfield. Following the completion of its flight program, the pilot prepared to return to the airfield. Based on observations from the air traffic controller regarding the windsock, the pilot was advised to land on runway 15 instead of runway 33. The pilot confirmed this wind direction by performing a low pass over runway 33, noting an easterly wind of approximately 8 knots.
The landing on runway 15 proceeded, and the pilot reported that the aircraft remained controllable during the approach and flare. After touchdown at 10:54, the pilot utilized reverse thrust to decelerate. Because this specific single-seat version of the G520 lacks a steerable nosewheel, directional control relied entirely on aerodynamic rudder effectiveness and wheel braking.
As the aircraft's speed dropped below 40 knots, it began to drift toward the left side of the runway. Despite full rudder deflection and braking input, the aircraft could not be maintained on the centerline. At a speed of approximately 20 knots, the aircraft exited the runway. During the excursion, the nosewheel assembly broke off, and all four propeller blades fractured upon contact with the ground. The pilot shut down the engine, closed the fuel valves, and cut the electrical power to prevent further damage.
There were no injuries to the pilot, but the aircraft sustained heavy damage.
The investigation
The BFU examined the wreckage and the mechanical systems of the aircraft. The investigation focused on the loss of directional control during the high-speed rollout and the physical damage sustained by the nosewheel and propeller. A technical inspection of the braking system was also conducted by the manufacturer.
Findings
- The aircraft drifted off the runway due to an inability to maintain directional control at low speeds.
- The right brake functioned insufficiently during the landing roll.
- A technical inspection by the manufacturer revealed air bubbles within the right braking system.
- The aircraft's design (single-seat version) lacks a steerable nosewheel, making it dependent on aerodynamic and braking forces for ground steering.