What happened
On 21 April 2018, a Hatz CB-1 biplane, registration G-BRSY, was performing a general aviation flight from a private airfield near Kilkenny to Coonagh Airfield (EICN). Following a normal touchdown on the asphalt runway, the aircraft began to track toward the left during the landing roll-out.
At the time of the incident, the aircraft was experiencing light crosswinds from the left. As the aircraft drifted off the paved surface, the left wheel encountered soft grass, which had been softened by recent rain. The wheel sank into the ground, causing the aircraft to pitch forward. The propeller struck the grass and the edge of the runway, eventually leading to the aircraft inverting onto its upper wing and tail. There were no injuries to the pilot or the single passenger on board.
The investigation
The AAIU examined the aircraft, the airfield conditions, and the meteorological data. The investigation confirmed that the Hatz CB-1 suffered substantial damage, including broken propeller blade tips, potential engine shock-loading, a buckled wing strut, and a bent wing tip.
Investigators noted that the runway at Coonagh Airfield is relatively narrow (9 metres wide) and was bordered by soft ground. The investigation also reviewed the inherent handling characteristics of tailwheel aircraft, noting their tendency to weathervane into the wind during ground operations in crosswind conditions.