The aircraft was landing on Runway 15 at Enniskillen, having flown in from Letterkenny Airfield, County Donegal. Following an approach which was “entirely stable in terms of height and speed”, the aircraft touched down but immediately ground-looped to the right, coming to rest with the right main landing gear collapsed inwards underneath the fuselage. Examination showed that several structural elements of the right main landing gear had broken, apparently in overload, consistent with right sideslip being present at touchdown. The pilot is unsure whether the ground loop occurred as a result of the collapse or had precipitated the collapse. He suggested that the right brake may have been locked on for some reason, although the wheel was found to rotate normally.