What was found
DURING HEAVY MAINTENANCE CHECK CENTER WING UPPER PANEL CORRODED AT RH APPROX STA 1172, XCW 6.5 AT S-22. AFTER FURTHER EVALUATION OF BLENDED OUT AREA AT RH APPROX STA 1172, XCW 6.5 AT S-22, BOEING FOUND BLENDED OUT LOCATION ACCEPTABLE AS A PERMANENT REPAIR IAW MD-11, MESSAGE: WGN-WGN-25-0035- 4C. THE AIRCRAFT WAS APPROVED FOR RETURN TO SERVICE.