What was found
DURING A SCHEDULED 50 HOUR TAIL BOOM INSP, A CRACK WAS FOUND ON THE VERTICAL STABILIZER. THE CRACK IS 6 INCHES LONG THROUGH THE AFT WEB BETWEEN THE AFT CAP ANGLES RIVET TO RIVET, AT APPROX WL118. THIS TAILBOOM INSP SPECIFICALLY CALLS FOR A CRACK INSP OF THIS AREA. THIS ACFT IS PRE CSN 76-220A, WHICH IS THE FIX FOR THIS PROBLEM. PRE CSN 76-220A ACFT REQUIRE A REPETITIVE 50 HOUR INSP OF THIS AREA, POST CSN 76-220A MOVES THIS INSP TO 300 HOUR REQUIREMENT.