What happened
During an approach and landing at Cascais aerodrome, a Beechcraft 18 touched down with excessive speed and an improper aircraft attitude, causing the aircraft to bounce on the first runway contact. Following a second touchdown, the aircraft entered a divergent dynamic characterized by successive deviations to the left and right. This resulted in a ground loop that sent the aircraft off the left side of the runway, rotating approximately 220 degrees from its initial heading. During this excursion, the right wingtip of the Beechcraft 18 struck a Cessna 152 that was holding on the taxiway awaiting takeoff for a flight instruction session.
The investigation
The GPIAAF investigation examined the aircraft condition, crew data, and environmental factors at the time of the event. The investigation noted that the pilot had not operated this specific aircraft model since 201 and held a valid PPL(A) with a multi-engine qualification. Environmental conditions at the time of landing included a cloudy sky and a wind from 290 degrees at 09 knots, which produced an 8-knot right crosswind component for runway 17. While some aircraft components showed signs of degradation due to inactivity or lack of preservation, investigators could not link the runway excursion to any mechanical failure.
Findings
Both crews were uninjured in the event. The Beechcraft 18 sustained damage to the rear fuselage, vertical stabilizers, and rudders after the tail wheel collapsed upon striking the edge of the taxiway. The right landing gear braking system was also damaged by ground contact. The Cessna 152 sustained substantial damage to its left wing and the left side of the cockpit area. The investigation identified inadequate piloting technique during landing involving excessive directional correction (PIO) as the most probable cause. A contributing factor was the pilot's reduced proficiency with this specific aircraft model under the reported wind conditions.