What was found
DURING A ROUTINE C CHECK INSPECTION FOUND TAIL SECTION FUSELAGE EXTERNAL SKIN CRACKED .75 INCH STA 1755.000-L-13 TO L14. REPAIR ACCOMPLISHED REMOVAL OF FASTENERS WITH THE REPAIR AREA AND EXISTING REPAIR DOUBLER. REMOVED DAMAGED SECTION. PERFORMED NDT INSPECTION, CLEANED, TREATED AND PRIMED AREA. FABRICATED A REPAIR DOUBLER, SHINS AND TWO INTERNAL FINGER DOUBLER. CLEANED TREATED AND PRIMED THE REPAIR PARTS. APPLIED PRC SEALANT ON FAYING SURFACES. INSTALLED THE REPAIR PARTS ON TAIL SECTION EXTERNAL SKIN USING NEW FASTENERS PER DOUGLAS STRUCTURAL MANUAL, ATI DWG W43-R13 AND FAA FORM 8110-3.