MECHANIC REPORTS ON AN AIRBUS A320 ARRIVING WITH A CHRONIC #2 ENG FIRE LOOP 'B' FAULT. DURING TROUBLESHOOTING; FOUND INSULATION ON WIRES SCRAPED AWAY; CONDUCTORS SHORTING; WIRES WRAPPED IN CELLOPHANE TAPE.

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AIRCRAFT ARRIVED WITH CHRONIC #2 ENGINE FIRE LOOP B FAULT. THE FAULT WAS PRESENT UPON ARRIVAL SO MY TROUBLESHOOTING LED ME TO TERMINAL BLOCK 450VT2 IN #2 ENGINE PYLON. THE INSULATION ON WIRES CF20-278 AND CF20-279 LEADING INTO THIS TERMINAL BLOCK WAS SCRAPED AWAY AND BARE CONDUCTORS WERE VISIBLE. WIRE CF20-279 PULLED EASILY OUT OF THE CONTACT WITH A SLIGHT PULL ON THE WIRE. THE HARNESS LEADING TO TERMINAL BLOCK 450VT2 WAS WRAPPED IN CLEAR CELLOPHANE TAPE; HIDING THE BARE CONDUCTORS AND SHORTING THE TWO BARE CONDUCTORS TOGETHER. WIRES CF20-278 AND CF20-279 HAD LOOSE SHRINK WRAP OVER THE BARE CONDUCTORS; TRYING TO HIDE THE DAMAGE BUT HAD SLID OFF THE BARE AREAS.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED WHEN ANOTHER MECHANIC HE WAS WORKING WITH NOTICED THE CELLOPHANE TAPE WRAPPED AROUND THE WIRE HARNESS GOING TO TERMINAL BLOCK 450VT2 ON #2 ENGINE; THEY REALIZED THERE WAS A PROBLEM. CELLOPHANE TAPE IS NOT ALLOWED. REPORTER STATED THE ENGINE FIRE LOOPS 'A' AND 'B' RUN PARALLEL AND COVER THE ENG FAN SECTION AND THE UPPER PYLON AND LOWER CORE AREAS. THE AIRBUS TROUBLESHOOTING MANUAL (TSM) DESCRIBES THE PROCEDURE THAT HAS MECHANICS SWAPPING INDIVIDUAL WIRES FROM TERMINAL BLOCK 'A' WITH TERMINAL BLOCK 'B' IN THE UPPER FWD PYLON; TO SEE IF A FAULT CONDITION SHOWS UP ON THE LOOP THAT DID NOT HAVE THE FAULT. REPORTER STATED FINDING THE WIRES WITH THE INSULATION SCRAPED AWAY; BARE CONDUCTORS CONTACTING AND SHORTING ALONG WITH THE DAMAGED TERMINAL CLIPS IN THE TERMINAL BLOCK 450VT2 THAT SHOULD HOLD THE WIRE ENDS; RAISED SERIOUS CONCERNS ABOUT THE ORIGINAL WORK PERFORMED. REPORTER STATED HE WAS INFORMED THE PROBLEM MAY HAVE ORIGINATED ALL THE WAY BACK TO A PREVIOUS OUTSIDE; INTERNATIONAL MAINT CONTRACT PROVIDER. BUT; DUE TO THE NUMBER OF TIMES SINCE THEN THAT MAINT HAS TRIED TO CORRECT THE CHRONIC CONDITION; NO FINAL DETERMINATION COULD BE MADE. HIS CARRIER HAS PUT OUT AN ALERT TO ALL THE MAINT STATIONS THAT WERE; OR MIGHT HAVE BEEN; INVOLVED WITH ENG FIRE LOOP ISSUE.