What happened
On September 3, 2013, a Cessna U206C, registration PT-DDG, departed from Aeródromo Brig. Protásio de Oliveira, PA, bound for Breves, PA. The flight was operated by Táxi-Aéreo Dourado Ltda. with one pilot and two passengers on board.
Shortly after takeoff, the pilot requested a lower altitude of 2,500 feet, likely due to cloud layers at 3,000 feet. Following this request, air traffic control lost both radar and radio contact with the aircraft. Minutes later, the control tower observed smoke in the departure sector. The aircraft was later discovered in a forested area approximately 4 kilometers from the airfield. The impact occurred at a steep 45-degree angle into trees, followed by a high-energy ground impact and a post-crash fire. All three occupants sustained fatal injuries.
The investigation
CENIPA investigators examined the wreckage and the propeller assembly. The investigation focused on the mechanical state of the propeller blades and the maintenance history of the aircraft. Investigators found that while the aircraft's maintenance logs were up to date and the engine had recently undergone an overhaul, there were discrepancies in the recorded flight hours of the propeller blades compared to the propeller hub.
Technical analysis of the propeller assembly revealed corrosion on the Blade Actuating Pins of all three blades. Specifically, the pin for blade number two had suffered a fatigue fracture. The investigation also considered the pilot's decision-making, noting that the pilot had successfully performed an emergency landing in a similar location six years prior to the same date, which may have influenced his attempt to steer the failing aircraft toward a known safe clearing.
Findings
- The primary cause of the accident was the fatigue fracture of a propeller blade actuator pin caused by corrosion.
- This failure caused the second blade to move to a minimum pitch position, creating an asymmetric propeller configuration that induced severe vibration, increased drag, and a significant loss of thrust.
- Maintenance procedures for the propeller overhaul were insufficient to detect the internal corrosion within the propeller hub.
- The sudden change in flight characteristics likely impaired the pilot's ability to maintain control or execute a successful emergency landing, leading to the collision with trees.