What was found
(CAN) DURING IMPORT OF THE ACFT, MAINTENANCE WAS CARRYING OUT ASB 212-90-63, THE REPETITIVE TAILBOOM BORESCOPE INSPECTION. IN ADDITION, THE LOWER LONGERONS WERE INSPECTED FOR CONDITION. A CRACK WAS NOTED IN THE LT LOWER LONGERON. THE TAILBOOM WAS REMOVED AND SENT TO A REPAIR SHOP. WHEN THE TAILBOOM WAS OPENED UP, THE LONGERON WAS FOUND TO HAVE A REPAIR APPLIED TO THE CRACK. THE REPAIR AND LONGERON WERE BOTH CRACKED AND SEPARATED. THE REPAIR WAS NOT APPROVED IAW THE SRM. A REPLACEMENT TAILBOOM WAS INSTALLED ON THE ACFT, AND RETURNED TO SERVICE. THE ORIGINAL UNIT IS UNDERGOING REPAIRS.