What happened
On February 26, 2005, a Toxo II experimental aircraft, registration PU-TOX, departed from the Americana Municipal Aerodrome (SDAI) in São Paulo, Brazil, for a local flight. The aircraft was operated by Escola Americanense de Aviação (EAA) and was carrying two crew members: an instructor and a pilot.
Approximately 25 minutes after takeoff, witnesses observed the aircraft in an uncontrolled state, performing wide wing movements of nearly 90 degrees at a low altitude. The aircraft subsequently impacted the ground in a residential area near the aerodrome. The impact occurred while the aircraft was in a stalled condition with a high sink rate. The collision resulted in two fatalities and the total destruction of the aircraft.
The investigation
CENIPA's investigation focused on the circumstances leading to the loss of control. The investigation established that the aircraft was an experimental model, assembled in Brazil from a kit. While the aircraft's manual listed high load factor limits (+10G to -6G), it did not explicitly define a maneuver envelope or prohibit specific aerobatic maneuvers.
The investigation examined the crew's actions and the flight preparation. It was noted that the flight was unplanned; the instructor had originally intended to conduct a check flight with a student in a different aircraft, but decided to fly the PU-TOX with the second pilot after a chance encounter. The aircraft took off with full fuel tanks, despite the instructor having previously requested fuel to be drained to improve performance for maneuvers.
Physical evidence at the scene showed that both pilots' hands were positioned over the single engine throttle, suggesting a possible joint effort to control the aircraft during the emergency. The investigation also noted that the aircraft's engine was producing power at the time of impact, as evidenced by marks on the reduction gearbox.
Findings
- Lack of flight planning was a primary contributing factor, as the sudden decision to fly led to an inadequate briefing and lack of preparation regarding flight profile and safety altitudes.
- Psychological factors, specifically high motivation and a lack of formal planning, led to a rushed takeoff.
- The aircraft was not certified for aerobatics, and the instructor had a history of performing maneuvers in this model despite manufacturer recommendations against it.
- The aircraft's manual lacked a specific maneuver envelope, which, combined with high load factor ratings, may have induced the crew to explore the flight envelope beyond safe limits.
- There was a possibility of uncoordinated cockpit management or confusion regarding command authority during the loss of control event.