What happened
On June 26, 2004, a pilot was conducting the first test flight of a recently purchased Viking MK 2 "Dragonfly" at Issoire aerodrome. Immediately after rotation during takeoff from runway 36, the pilot noted a drop in engine RPM of more than 300 revolutions per minute, accompanied by a sharp increase in oil temperature.
Due to the limited runway length and the presence of a cornfield at the end of the strip, the pilot opted to perform a left turn to approach runway 18 at a low altitude of approximately five meters. During the final approach, the pilot noted a hot odor. Upon crossing the runway threshold, the pilot shut down the engine, closed the fuel circuit, and cut the electrical power. While attempting to stop during the landing roll, the aircraft overran the end of the runway. The aircraft struck a 30-centimeter depression located five meters past the runway end, causing the aircraft to tilt on its wing, before settling back onto its wheels and coming to a halt.
The investigation
The investigation focused on the mechanical failure of the Limbach SL 1 700 E engine. An examination by the manufacturer revealed that the front crankshaft bearing had seized due to obstructed lubrication channels.
Investigators also reviewed the aircraft's maintenance history. The aircraft had not flown for approximately two years prior to the incident. While the engine had logged roughly 370 hours since installation, and a 100-hour inspection had been performed following the recent purchase, the specific maintenance actions taken to preserve the engine's operational state during its two-year period of inactivity could not be determined.