A B767-300 MECH DESCRIBES THE EVENTS THAT LED TO HIS FAILING TO INSTALL THE MAIN GEAR WHEEL SPACER DURING TIRE CHANGE. FLT CREW LATER; UPON LNDG; HAD BRAKE OVERHEAT MESSAGE AND BRAKE BADLY DAMAGED.

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I WAS INVOLVED WITH HELPING MR X AND MR Y WITH CHANGING TIRE 2F DUE TO WEAR. WE HAD A COPY OF MAINT MANUAL. THE OLD TIRE WAS REMOVED AND I INSPECTED THE AXLE FOR WEAR; THE PRESENCE OF THE AXLE SPACER; AND COATED THE SURFACES WITH RED GREASE IN PREPARATION TO INSTALLING THE NEW TIRE. THE 3 OF US GUIDED THE NEW TIRE ASSEMBLY ONTO THE AXLE; BUT IT STARTED TO BIND UP. FURTHER ATTEMPTS TO INSTALL RESULTED IN THE OUTER WHEEL BEARING POPPING OUT. AT THIS POINT; I TOLD MR X AND MR Y TO TAKE IT OFF WHILE I WENT TO THE RACK TO GET ANOTHER TIRE ASSEMBLY. THE SECOND WHEEL ASSEMBLY WENT ON WITHOUT A PROB. MR Y TOOK THE 2 (OLD AND FIRST NEW ASSEMBLY) TO THE TIRE AREA WHILE MR X AND I FINISHED INSTALLING THE NEW ASSEMBLY. MR X TORQUED THE ASSEMBLY WHILE I SPUN THE TIRE. WHEN FINISHED; I REINSTALLED THE SAFETY BOLTS AND HUBCAP AND THE MAIN LNDG GEAR WAS LOWERED TO THE GND. AFTER HEARING WHAT HAPPENED; I REALIZED THAT I FOLLOWED MY USUAL HABIT OF CHKING EVERYTHING PER THE MAINT MANUAL WHEN THE ORIGINAL WHEEL ASSEMBLY WAS REMOVED. IT NEVER OCCURRED TO ME TO CHK IT AGAIN WHEN I ROLLED OUT THE SECOND ASSEMBLY. A LESSON TO ME IS TO CHK FOR THE SPACER BEFORE ANY ASSEMBLY IS INSTALLED; EVEN IF I KNOW IT SHOULD BE THERE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THE WHEEL SPACER HE FAILED TO CHK WHEN INSTALLING THE SECOND 'NEW' WHEEL ASSEMBLY WAS FOUND LATER ON THE FIRST 'NEW' WHEEL THAT WOULD NOT QUITE GO ONTO THE L MAIN GEAR AXLE. BY THE TIME THIS SPACER WAS NOTICED; STUCK ON THE FIRST 'NEW' WHEEL/TIRE ASSEMBLY; THE B767 HAD ALREADY LANDED DOWNLINE WITH A BRAKE OVERHEAT WARNING MESSAGE. RPTR STATED THE BRAKE ASSEMBLY WAS FOUND SEVERELY OVERHEATED AND DAMAGED.