What happened
On October 25, 1976, a PT-TBA, a twin-engine aircraft, was performing a takeoff from the Petrolina Aerodrome in Pernambuco, Brazil. Shortly after departure, passengers reported experiencing intense vibrations. Approximately 45 seconds into the flight, the pilot notified the control center that the aircraft was experiencing serious problems and that they were going to crash.
Following the failure of the right engine, the aircraft entered a steep left-hand turn with a significant loss of altitude. Witnesses observed the aircraft flying in an attitude typical of a pre-stall condition. The aircraft ultimately collided with the ground, resulting in a post-impact fire that destroyed the airframe. The two pilots perished in the impact, while the passengers were treated at a local hospital.
The investigation
CENIPA investigators examined the wreckage and interviewed witnesses to reconstruct the final moments of the flight. The investigation focused on the mechanical state of the engines and the flight maneuvers performed by the crew. Investigators noted that the right engine's propeller blades indicated it was in a windmilling state, while the left engine's blades indicated it was still producing power at the moment of impact.
Due to the total destruction of the aircraft by fire and the deaths of the crew, investigators were unable to pinpoint the exact mechanical cause of the right engine's failure. However, the investigation analyzed the flight path and the crew's response to the emergency. The investigation also reviewed maintenance records, though it concluded that maintenance history had not been sufficiently researched to establish a definitive cause-and-effect relationship regarding the engine failure.
Findings
- The right engine experienced a failure due to undetermined causes.
- The crew lost control of the aircraft due to insufficient airspeed and a high bank angle, which placed the aircraft in a pre-stall condition.
- The pilot's attempt to maneuver the aircraft contributed to the loss of control, as the aircraft was flying at a low speed and high inclination.
- The investigation found that the operational handling of the aircraft was deficient during the emergency.