Flight and Emergency
The twin-engine airplane departed São Paulo-Guarulhos Airport at 0440 local time on postal service flight TTL5561 to Londrina, with two pilots on board. About one hour into the flight, while cruising at 18,000 feet, the autopilot disconnected as the crew experienced technical problems with the elevator trim system. The captain instructed the copilot to pull the circuit breaker, but the copilot did not immediately understand the command. He executed the request a few seconds later.
Shortly after, the aircraft nosed down, and the Vmo alarm sounded, indicating the speed exceeded the maximum operating speed. The crew reduced engine power to 10%, but the aircraft entered an uncontrolled descent.
Crash and Damage
The aircraft crashed at a speed of 366 knots in an open field 38 km south of Paranapanema. It was totally destroyed upon impact, and both pilots were killed. Some debris were found at a depth of three meters.
Investigation Findings
The official investigation identified several findings. The pilots' perception of the situation was affected by a lack of specific training and procedures, coupled with limited time for action and unclear communications. Communication between the crew was not clear during the emergency, causing the copilot to initially misunderstand the requested action, which increased the time to disarm the circuit breaker.
The company had not provided regular CRM training to pilots. The captain had not received simulator training for over a year. However, it was impossible to determine if regular training would have prevented the accident.
The removal of the pilot from his seat at the time of the emergency may have increased the time to identify and correct the problem, but it could not be established if the accident would have been avoided had he remained in the cockpit. The copilot was slow to understand and initiate corrective actions, even after the alarm sounded.
Operational testing under J IC 27-32-00 allowed partial completion of procedures due to lack of clarity, enabling the aircraft to be released for flight with a defective relay. Although the elevator trim system was certified, the manufacturer's manuals did not include procedures for emergency triggering of the compensator, nor replacement intervals for trim system components in the "Time Limits" sections. Normal and reserve systems were not independent, and the system had a low tolerance for errors.