Incident Overview
A domestic IFR cross-country flight experienced a slight vibration while climbing through flight level 310 en route to an assigned altitude of FL390. A passenger seated on the left side of the airplane observed portions of the skin on a non-structural wing panel on the left wing peeling off and separating from the wing. The passenger informed a crewmember of the condition. The flight crew made a precautionary landing without further incident.
Post-Flight Examination
Examination of the airplane revealed that a section measuring 48 inches wide by 31 inches long had separated from the trailing edge of the fixed trailing edge upper panel on the left wing. Additionally, a three-inch portion of the trailing edge on the left fore flap panel was also damaged and had separated from the airplane.
Maintenance Findings
According to maintenance personnel contracted by the operator, the delamination of the honeycomb panel was the result of water contamination. No other contributing factors were identified.
Operational Outcome
The airplane landed safely, and no injuries were reported. The incident remains under review by the operator's maintenance team.