Incident Overview
On 28 May 2006, at approximately 13:05 UTC, a Boeing Stearman A75N1 biplane (registration N62TS) was performing a demonstration flight over the town of Seia, Portugal, as part of an aeronautical festival. During the flight, the pilot noticed a fuel leak from the tank vent onto the upper left wing. Uncertain of the cause, the pilot decided to return to Seia Aerodrome for a precautionary landing.
Landing Maneuver and Loss of Control
The pilot landed on runway 08, touching down on the main wheels while keeping the tail raised. Shortly after touchdown, the aircraft began to drift left of the runway centerline. To correct this, the pilot applied right rudder and momentarily increased engine power. This input caused the aircraft to yaw sharply to the right. The left lower wingtip contacted the runway surface, and the aircraft departed the runway to the right, crossing the boundary fence before coming to rest in the adjacent field. The final position was vertical, with the engine and right wing leading edge on the ground and the tail in the air.
Injuries and Damage
The pilot, who was the sole occupant, was uninjured and required assistance from the fire brigade to exit the aircraft. The aircraft sustained light damage, including deformation to the left wing leading edge and one propeller blade. No third-party damage occurred.
Investigation Findings
The investigation determined that the fuel leak was attributed to overfilling and thermal expansion of fuel. The pilot held a valid ATPL(A) license with appropriate ratings and had logged 13:40 hours on type. The aircraft had a valid special airworthiness certificate and had undergone the recommended maintenance.
Probable Cause
The incident was caused by deficient piloting technique that did not ensure directional control of the aircraft, allowing it to depart uncontrolled to the right side of the runway.