As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING THE PROCESS OF A NON-SCHEDULED INSPECTION, THE LEFT WING UPPER SPAR CAP STRAP WAS FOUND CORRODED AROUND THE EDGES. FURTHER, NDT INSPECTION REVEALED CORROSION BETWEEN THE STRAP AND THE DOUBLER. CAUSE OF THE CORROSION COULD HAVE BEEN IMPROPER SEALING AROUND THE PERIPHERY OF THE STRAP. SB 500-57-13 WAS PERFORMED TO REPLACE THE STRAP.