What happened
On January 30, 2003, an EMB 810D (SENECA III), registration PT-RYY, was performing a flight from Barreiras to Santa Rita de Cássia, Bahia, carrying a pilot and three passengers. During the approach to the destination, the pilot encountered clouds near the runway and utilized the autopilot to navigate around them.
Upon disengaging the autopilot, the pilot reported a sudden pitch-up tendency, which he believed was caused by a malfunction in the elevator trim system. In an attempt to regain control, the pilot requested assistance from a passenger to help manipulate the controls. The pilot then deactivated the aircraft's master switch to cut electrical power, intending to stop the perceived trim malfunction. However, this action also disabled the stall warning horn. As the aircraft lost airspeed and altitude, the pilot deployed flaps to maintain lift, which increased drag and further degraded performance. The aircraft ultimately struck the ground at a high angle of attack with low power, followed by a post-impact fire that destroyed the aircraft.
The investigation
The CENIPA investigation examined the aircraft's maintenance records, the pilot's experience, and the physical evidence at the crash site. While the pilot reported a trim runaway, investigators found that the trim actuator's worm gear was in a normal position, suggesting the malfunction may not have occurred as described. The investigation also noted that the aircraft was within weight and center of gravity limits.
Investigators found that the pilot's decision to cut the electrical power was a critical error, as it silenced the stall warning during a high-risk phase of flight. Furthermore, the investigation noted that the pilot's request for a passenger to assist with the flight controls likely caused additional confusion and hindered effective control of the aircraft's pitch and airspeed.