What happened
On January 20, 2016, an AT-401B aircraft, registration PT-WFX, operated by Viagro Vidotti Agro Aérea Ltd., experienced an engine failure shortly after takeoff from 14 Bis Aerodrome in Londrina, Brazil. While attempting to perform a low-altitude reversal to return to the runway, the aircraft lost altitude and struck the ground at a 45-degree wing tilt angle near state highway PR-545.
Following the initial impact, the aircraft collided with a vehicle traveling on the highway. The collision caused both the aircraft and the vehicle to catch fire, leading to the total destruction of the aircraft's cockpit, engine mount, and fuselage. The accident resulted in six fatal injuries among the occupants of the vehicle and two serious injuries to the vehicle's other passengers, while the pilot sustained serious burns.
The investigation
CENIPA's investigation focused on the mechanical failure of the powerplant and the pilot's emergency maneuvers. Investigators examined the engine components and found that the cylinder head #4 had separated from its housing. Technical analysis of the engine revealed that the failure was caused by cracks resulting from material fatigue.
The investigation also scrutinized the aircraft's maintenance records, finding that the airframe, engine, and propeller logbooks were outdated. Specifically, the 1,000-hour inspection records were missing, and the engine was operating significantly past its expected interval since its last major inspection. Furthermore, investigators evaluated the pilot's decision-making process and the use of personal protective equipment during the emergency.
Findings
- The primary cause of the engine failure was material fatigue in the cylinder head #4, which led to a loss of compression.
- The pilot's decision to attempt a return to the runway via a steep reversal curve at low altitude was outside the aircraft's flight envelope and contributed to the loss of control.
- Inadequate decision-making, driven by a desire to avoid damage to the aircraft and maintain professional credibility, led to an unsuccessful emergency maneuver.
- Maintenance oversight within the operator's organization resulted in outdated logbooks and a lack of traceability for critical engine inspections.
- The pilot's injuries were aggravated by the failure to wear flight gloves, which could have mitigated the severity of the burns.