What happened
On November 10, 2015, a Cessna 650 (registration PT-WQH) was performing a personnel transport flight from Brasília to São Paulo. During the pre-flight cockpit preparation, the crew noted the operation of the pitch trim system. The flight proceeded normally until approximately thirty minutes after takeoff, while the aircraft was climbing through FL370.
During this phase, the cockpit voice recorder captured the distinct sound of the horizontal stabilizer moving. Immediately following this movement, the aircraft entered a high-speed, steep descent. The aircraft struck the ground at a farm in Guarda-Mor, Minas Gerais, and was destroyed. All four occupants—two crewmembers and two passengers—perished in the accident.
The investigation
CENIPA's investigation focused on the mechanical behavior of the pitch trim system and the crew's pre-flight procedures. Investigators examined the aircraft's primary and secondary pitch trim systems, which are designed to balance the aircraft longitudinally. The investigation also reviewed maintenance records from September 2015 and the crew's use of the cockpit checklists.
Technical analysis of the wreckage and flight recorders revealed that the aircraft experienced an uncommanded movement of the horizontal stabilizer. While investigators could not definitively link recent maintenance to the failure, they noted that the lack of detailed service orders made it difficult to rule out incomplete inspections of the pitch trim system. Additionally, the investigation looked into whether the crew had properly executed the Warning Systems Check during the cockpit preparation.
Findings
- The uncommanded movement of the horizontal stabilizer was the primary factor leading to the loss of control.
- The crew's decision-making process contributed to the accident, as the Warning Systems Check in the Cockpit Preparation Checklist appears to have been bypassed, preventing the identification of the trim system abnormality.
- There was evidence of a potential rush to depart, despite the crew having previously discussed the pitch trim system's operation.
- The possibility of outdated abbreviated checklists prevented the crew from performing the necessary Stabilizer Trim Backdrive Monitor test.
- Inadequate supervision of maintenance activities and insufficient documentation of operational verification flights were identified as contributing factors.