As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING 600 HOUR INSPECTION, FOUND TORQUE LOSS ON UPPER VERTICAL FIN BOLTS WHERE IT ATTACHES TO THE TAILBOOM. REMOVED UPPER AND LOWER FIN ASSY.FOUND THAT DOUBLER HOLDING NUT PLATES IS WORKING AGAINST TAILBOOM RING FRAME. HEARD A POPPING CRACKLING SOUND FROM UPPER UPPER DOUBLER DURING FIN REMOVAL. SUPPECTING CRACK UNDER DOUBLER AMC ENGINEERING CONTACTED FOUND DURING 600 HR INSPECTION. *** THIS AIRCRAFT REMAINS OUT OF SERVICE AT THE TIME OF THIS SUBMISSION ***