As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING THE INSTALLATION OF SHOULDER HARNESS KITS, THE HEADLINER WAS REMOVED. CORROSION ON CARRY THRU SPAR FORE AND AFT TOP SPAR CAPS AND SKIN WAS NOTICED. CORROSION WAS ALSO PRESENT AT LEFT AND RIGHT ROOT RIBS. LEFT ROOT RIB HAD SMALL CRACK. NO FURTHER ACTION TAKEN.