As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING "C" CHECK, NR 4 SLAT HAS SEVERAL CRACKS IN RIB IB SIDE OF THE ACTUATOR, VIEWED THRU THE ACCESS HOLE. CA: REMOVED DAMAGED RIB AND INSTALLED NEW, PN 65-17276-9 PO NR 3348104 IAW 727 SRM 51-30-2, REMOVED AND REPLACED THE NR 4 SLAT FOR STRUCTURAL ACCESS IAW B727 MM 27-81-11.