What was found
C/W EXTRA SB 300-2-95 ISSUE B. INSTALLED REPAIR PER FACTORY DRAWINGS. PERFORMED AT TT 856.3 HOURS. INSPECTIONS NO LONGER RECURRING IAW SB 300-2-95 ISSUE C. AT 1,052.4 HOURS, UPPER LEFT LONGERON AT REPAIR BROKE IN TWO. ALSO BROKE CROSS MEMBER IN TWO. RECOMMEND AN AD BE ISSUED ON AIRCRAFT WITH THIS MODIFICATION. SUBMITTER STATED FOURTH AIRCRAFT TO FAIL WITH THIS REPAIR.