What was found
(CAN) DURING INSPECTION, THE TAIL DE-ICE BOOTS DID NOT INFLATE DURING OPS TEST. INVESTIGATION NOTED THE TUBE SUPPLYING AIR PRESSURE TO THE RT HORIZONTAL STABILIZER DE-ICE BOOT HAD SPLIT APPROXIMATELY .8750" LONG. THE SPLIT OCCURED AT THE END OF THE HOSE THAT ATTACHES TO THE DE-ICE BOOT NIPPLE. THE SPLIT STARTED WHERE THE TUBE GOES OVER THE BEAD OF THE NIPPLE ON THE DE-ICE BOOT. THIS PART OF THE TUBE IS DIFFICULT TO INSPECT AS THE DE-ICE BOOT MUST BE REMOVED TO SEE THE NIPPLE AND AIR SUPPLY TUBE. THE TUBE WAS REPLACE WITH NEW AND THE SYS TESTED OK. 2 OTHER ACFT IN THE FLEET OF THE SAME TYPE WERE FOUND TO HAVE THE SAME TYPE OF SPLITS IN THE DE-ICE TUBING IN THE TAIL AREA, EITHER THE HORIZONTAL STABILIZER DE-ICE BOOT TUBE OR THE VERTICAL STABILIZER DE-ICE BOOT TUBE.