As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING HEAVY CHECK MAINTENANCE FOUND CRACK ON RIB 12A INTERNALLY ON RH HORIZONTAL BETWEEN MID SPAR AND FRONT SPAR JUST AFT OF 4TH RIVET FROM FRONT SPAR UPPER RIVET ROW. REMOVED AND REPLACED RH HORIZONTAL RIB 12A REF EMB SRM 51-40-08. A/C REMAINS IN CHECK.