What was found
3 CRACKS WERE FOUND IN LWR SUPPT E MODEL MN GEARBOX WAS REMOVED FROM SERVICE FOR O/H IN1995. IN DECEMBER OF 2001, SUPPT WAS MACHINED TO REMOVE CORROSION. AFTER MACHINING, CRACK WAS VISUALLY DETECTED IN MOUNTING LUG HOLE NR 4 AS INSTALLED ON AC. FLUORESCENT PENETRANT INSP VERIFIED THIS WHILE DETECTING 2 ADDITIONAL CRACKS IN MOUNTING LUG HOLE NR 1 AND NR 4, FOR A TOTAL OF 3 CRACKS. LONGEST CRACK WAS .750 INCH STARTING FROM BOTTOM (MATING) SURFACE EXTENDING AT A 45 DEGREE ANGLE THROUGH 45 DEGREE CHAMFER AND UP INTO WALL OF.9730 DIA MOUNTING HOLE. NOTE: 12 MOUNTING HOLES EXIST. HOLES ARE FOR BOLTS WHICH ATTACH THE MN GEARBOX TO AIRFRAME. NO PROBABLE CAUSE DETERMINED AT THIS TIME.