What happened
On December 27, 2004, a Maule M-7-235B, registration PT-WBM, was performing a routine logistics flight near Barcelos, Amazonas. The aircraft, operated by Negrotur Turismo Ltda., had departed from the Rio Negro Lodge to transport supplies to the Rio Araçá region.
During the return leg of the flight, while maintaining an altitude of approximately 500 feet, the pilot executed a right-hand climbing turn followed by a left-hand reversal to align with the landing axis. As the aircraft stabilized on the final approach, it experienced a sudden, violent yaw. Despite the pilot's attempts to correct the flight path using the rudder and control column, the aircraft lost control and struck the surface of the Rio Negro with significant force. The impact caused the aircraft to submerge, resulting in severe injuries to the pilot and severe damage to the airframe.
The investigation
CENIPA's investigation focused on the sudden loss of control and the physical state of the aircraft. Investigators found that the aircraft had previously been involved in a ground collision with a light pole during towing operations at the company's hangar. This prior incident had caused damage to the left wing's leading edge and structural attachment points.
Crucially, the investigation revealed that the repairs following the pole collision were performed by a mechanic at the operator's facility without notifying the Civil Aviation Authority. No official damage report was filed, and no authorization for repairs was obtained, making it impossible to verify the adequacy of the structural restoration. The investigation also noted that essential aircraft logs and maintenance records were lost when the aircraft sank.
Findings
- The sudden yaw and subsequent loss of control were likely caused by a structural failure of the wing.
- The wing failure may have been the result of improper repairs following a previous collision with a utility pole.
- The previous impact may have introduced plastic deformations or hidden cracks into the wing structure, which eventually failed under aerodynamic loads during the landing maneuver.
- Inadequate management oversight led to unauthorized maintenance procedures and a lack of regulatory compliance regarding structural repairs.