As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SKIN OF LEFT VERTICAL STABILIZER CRACKED. REMOVED SKIN AND FOUND RIB P/N 33640000-11 WITH UNSHOT RIVETS AT ATTACH POINT TO REAR SPAR OF VERTICAL STABILIZER. IT APPEARS THAT THIS WAS THE FIRST TIME THIS SKIN WAS REMOVED SINCE DATE OF MANUFACTURE. RIVETS CAN BE INSPECTED THROUGH LIGHTNING HOLE IN REAR SPAR TO SEE IF SHOT.