As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE TAILPLANE STRUCTURE MAIN RIB FORWARD FLANGES AT THE TAILPLANE LOWER RIB ATTACHMENT FITTING FOUND CRACKED. THE CRACKING IS FATIGUE RELATED. SUBMITTER STATED TO CORRECT PROBLEM, INSTALL MOD. 3/935 IAW DHC-3 SB 3/50. NOTE: THE DYE PENETRANT METHOD PER SB 3/46 WOULD NOT DETECT CRACKING ON MAIN RIB DUE TO BEARING PLATES COVERING CRACKS.