As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE PERFORMING CPC TASK CARD C55-391-30, THE VERTICAL STABILATOR'S UPPER RT CLOSURE RIB WAS FOUND EXFOLIATED ON ITS OUTBOARD SIDE JUST FORWARD OF THE FORKED END OF THE AFT HINGE POINT FITTING FOR THE HORIZONTAL STABILIZER. CORROSION WAS REMOVED AND FOUND TO BE WITHIN LIMITS PER SRM 55-30-1, FIGURE 1. SUSPECT CAUSE: UNKNOWN.