B757-200 MECH INSTALLED A 'BORROWED' PART THAT HAD AN EXPIRED SHELF LIFE.

Narrative

ON APR/SUN/01; I WAS WORKING ON AN ACR X B757-200. I WAS ASSIGNED TO TROUBLESHOOT A HYD PRESSURE PROB. WE HAD NARROWED IT DOWN TO THE CTR ELECTRIC PRESSURE CASE DRAIN FILTER PUMP MODULE. I REPLACED THE UNIT WITH A LOANER PART FROM ACR Y AIRLINES DUE TO LACK OF PARTS AT ACR X. THE PART WAS DELIVERED TO ME ON THE RAMP OF ZZZ ARPT BY ACR X STORES DEPT. I OPENED THE CONTAINER AND REMOVED THE PART AND DOCUMENTATION. I WAS NOT FAMILIAR WITH THE SERVICEABILITY TAG BUT SAW SERVICEABLE STAMPED ACROSS THE TAG; VERIFIED THE PART AND SERIAL NUMBERS AND CONTINUED TO INSTALL THE PART ON THE ACFT PER ACR X MAINT MANUALS. ON JUN/THU/01; I WAS CONTACTED BY MGMNT AND INFORMED THAT THE PART THAT I HAD INSTALLED ON ACFT XXX WAS NOT SERVICEABLE AT THE TIME OF INSTALLATION DUE TO AN EXPIRED ROTATABLE SHELF LIFE WHICH HAD EXPIRED ON FEB/SUN/01. ON JUN/WED/01; AN FAA INSPECTOR HAD REQUESTED TO CONFIRM THE VALIDITY OF A SERVICEABLE TAG. AN INSPECTION WAS CONDUCTED AND COULD NOT CONFIRM SERVICEABILITY OF THE PART SO THE ACFT'S NEXT FLT WAS CANCELED AND THE PART WAS CHANGED. I BELIEVE THAT THIS INCIDENT WAS CAUSED BY POOR INVENTORY MGMNT ON THE PART OF ACR Y AIRLINES. THE PART HAD BEEN EXPIRED FOR MORE THAN 2 MONTHS AND WAS STILL IN THEIR SERVICEABLE STOCK. IF THE PART HAD BEEN REMOVED FROM THEIR STOCK ON FEB/SUN/01; I WOULD HAVE NEVER RECEIVED IT AND THIS INCIDENT WOULD NOT HAVE OCCURRED. I WILL DO MY PART TO SEE THAT THIS NEVER HAPPENS AGAIN BY INSPECTING EVERY DETAIL OF THE DOCUMENTATION AND IF UNSURE CONSULT MGMNT OR STORE'S PERSONNEL.