What was found
DURING WING INSPECTION, FOUND EVERY WHERE THAT SOUNDPROOF INSULATION COMES IN CONTACT WITH THE FERROUS AFT SPAR CAP, THAT CORROSION SETS IN DUE TO THE MOISTURE THAT THE INSULATION HOLDS.
As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
DURING WING INSPECTION, FOUND EVERY WHERE THAT SOUNDPROOF INSULATION COMES IN CONTACT WITH THE FERROUS AFT SPAR CAP, THAT CORROSION SETS IN DUE TO THE MOISTURE THAT THE INSULATION HOLDS.