What happened
On October 10, 1994, at approximately 16:55, a Beechcraft D-50B, registration PT-BFB, departed from Carlos Prates Aerodrome (SNCH) for a local adaptation flight. The aircraft was occupied by three crew members. During the traffic pattern, while performing a right turn to enter the downwind leg, the aircraft suddenly experienced a loss of control. The aircraft entered a descending flight attitude and collided with a residential building approximately 1.5 km from the aerodrome.
The impact caused the aircraft to explode. The accident resulted in the deaths of all three crew members and two residents of the house. A third resident sustained minor burns. The aircraft was destroyed beyond repair.
The investigation
CENIPA's investigation focused on the mechanical state of the aircraft and the proficiency of the crew. Investigators found that the left propeller was in the feathered position, while the right propeller was in the normal flight position, indicating a failure of the left engine. Additionally, the rudder trim was found fully deflected to the right.
The investigation revealed that the aircraft's airworthiness certificate had been suspended prior to the flight due to an expired annual maintenance inspection. Maintenance services were being performed by mechanics hired directly by the owner at workshops that were not approved for this specific aircraft model. Furthermore, the pilots lacked sufficient transition training or experience in the Beechcraft D-50B; the pilot in command had only one hour of experience in the type, and the co-pilot had none.
Findings
- Engine Failure: The left engine failed, leaving the aircraft with power only from the right engine.
- Improper Control Application: The crew applied incorrect rudder trim; the trim was fully deflected to the right, whereas it should have been moved to the left to assist with the asymmetric thrust of the single operating engine.
- Loss of Control: A lack of cockpit coordination and a distraction caused by the engine failure led the crew to fail in monitoring the aircraft's airspeed, resulting in a low-altitude stall.
- Inadequate Training: The pilots had insufficient theoretical or practical instruction regarding the specific characteristics of the aircraft model.
- Maintenance Deficiencies: The aircraft was maintained by non-certified personnel using unapproved workshops, and essential engine and propeller logbooks were missing.
- Human Factors: The pilot in command exhibited excessive self-confidence, while the other crew members showed signs of anxiety, both of which compromised effective decision-making during the emergency.