Incident Overview
During descent for landing, the aircraft experienced an uncommanded roll to the left. The flight crew responded by disengaging the autopilot and the yaw damper. After noticing no apparent yaw problem, they reengaged the yaw damper. The descent continued and the landing was completed without further incident.
Post-Flight Examination
Following the flight, inspection of the electronics compartment revealed contamination on the connector plugs and wiring harnesses attached to the E-1-2 and E-1-3 shelf disconnect brackets. The contaminants were identified as water and a blue residue.
Sources of Contamination
The water originated from a current leak in the main cabin door. The blue residue was attributed to a previous leak from the forward lavatory. The presence of these contaminants on the electrical components likely interfered with normal system operation, causing the uncommanded roll.
Crew Actions
The flight crew correctly identified the roll and took appropriate steps by disengaging the autopilot and yaw damper. Their decision to reengage the yaw damper after confirming no yaw issues was based on observed conditions. The landing was executed safely.
Conclusion
The incident was directly linked to the contamination of critical electrical connections in the electronics compartment. No further anomalies were reported after landing.