What happened
On July 7, 2010, at 10:00 UTC, a Zephyr 2000 ultralight aircraft, registration CS-UOB, was performing a training and fire reconnaissance flight from Santarém to the Valdonas airfield in Tomar, Portugal. The flight crew consisted of two pilots, including a more experienced pilot acting as the pilot monitoring.
As the aircraft approached runway 15, the pilot flying configured the aircraft with 15 degrees of flaps (position I) and maintained a speed of 55 knots. Upon touchdown at the beginning of the second third of the runway, the pilot perceived that the aircraft was not decelerating sufficiently. In an attempt to discontinue the landing, the pilot initiated a go-around by applying power. However, the remaining runway length was insufficient to allow the aircraft to accelerate to a safe flying speed. The aircraft failed to gain necessary lift, entered a stall during the initial climb phase, and subsequently collided with the ground approximately 200 meters beyond the end of the runway in a vineyard. The impact caused substantial damage to the aircraft's propeller blades, landing gear, and wings, but there were no injuries to the crew.
The investigation
The GPIAA investigation examined the aircraft's maintenance records, flight controls, and engine performance. The investigation confirmed that the aircraft's airworthiness documents were valid, the mass and balance were within manufacturer limits, and there were no mechanical failures in the flight control surfaces or flaps prior to the accident. The investigators also noted that the aircraft's engine, while providing a good rate of climb, produced significant torque effects that require active rudder control. The investigation focused on the crew's decision-making process, cockpit discipline, and the aerodynamic characteristics of the aircraft during low-speed maneuvers.