What was found
THIS AC WAS NEW IN 3/3/2002. LT AND RT SPINNER BULKHEADS HAVE HAD TO BE REPLACED TWICE. FIRST SET OF SPINNER BULKHEADS WERE REPLACED 12/28/2004, WITH 563.3 HOURS ON THEM. PROPS WERE BALANCED TO PREVENT FURTHER PROBLEMS. SECOND SET OF SPINNER BULKHEADS WERE REPLACED 8/26/05 WITH 165.9 HOURS ON THEM. FINDING CRACKS CAN BE DIFFICULT BECAUSE BULKHEAD IS SANDWICHED BETWEEN 2 SHIMS. FIRST SUSPECTED THAT THERE WAS ONLY 1 CRACK ON EACH BULKHEAD BUT AFTER REMOVING BULKHEAD AND THE SHIMS, NOTICED THAT EVERY HOLE HAD A CRACK COMING FROM IT. PROBABLE CAUSE COULD BE IMPROPER INSTALLATION OF PROPELLER MOUNTING BOLTS OR DEFECTIVE MATERIAL. RECOMMEND TAKING CLOSE LOOK EACH 100 HR, IF POSSIBLE LOOKING UNDER SHIMS. (K)