AN A&P MECH; FORCED TO WORK HIS JOB ALONE; FAILS TO TIGHTEN THE OIL LINE PROPERLY ON THE #4 SCAVENGE XMITTER FOR #2 ENG OF A B757-200 WHICH; ON THE NEXT DAY; RESULTS IN AN INFLT ENG SHUTDOWN AND DIVERSION OF THE FLT TO MCI; MO.

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ON JUL/FRI/02; I WAS ASSIGNED TO ACFT X TO WORK 'R ENG OIL SEAL' STATUS MESSAGE WITH MR Y AS MY PARTNER. AFTER TROUBLESHOOTING; IT LED TO THE REMOVAL OF THE #4 BEARING SCAVENGE XMITTER. AT THIS POINT; I STARTED TO REMOVE XMITTER LOCATED AT 9 O'CLOCK POS. AT THIS TIME MR Y WAS REMOVED FROM JOB TO GO ON A FIELD SVC. ON INSTALLATION; I NOTICED FROM MAINT MANUAL THAT I HAD REMOVED WRONG XMITTER. I THEN BEGAN TO REINSTALL XMITTER. AFTER TIGHTENING OIL LINES; I WAS HAVING TROUBLE INSTALLING ELECTRICAL CONNECTOR. SO I DECIDED TO LOOSEN OIL LINE TO LOWER 'B' NUT SO I COULD PUT A MIRROR IN TO CHK PINS AND SLOT OF CONNECTOR ON XMITTER. I THEN WAS ABLE TO CONNECT CANNON PLUG AND OIL LINE. I THEN NOTICED A TIGHT CLRNC BTWN 'B' NUT AND AIR PRESSURE LINE AND CHKED FOR PROPER CLRNC USING MIRROR. CLRNC WAS SUFFICIENT; AND I BELIEVE AT THIS TIME I FAILED TO TIGHTEN OIL PRESSURE LINE ON PRESSURE XMITTER. I THEN CONTINUED JOB REMOVING CORRECT SCAVENGE XMITTER LOCATED AT 6 O'CLOCK POS. I THEN INSTALLED NEW XMITTER AND TIGHTENED OIL LINE AND CANNON PLUG. I THEN HAD RUN MANUAL RUN ENG FOR 5 MINS AT IDLE AND CHKED FOR LEAKS AND NONE NOTED AT THIS TIME. STATUS MESSAGE WAS CLRED AT THIS TIME AND ITEM SIGNED OFF. ACFT WAS THEN RELEASED FOR SVC. ON INITIAL FLT ON THE NEXT DAY; ZZZ-SFO; CREW ENCOUNTERED LOSS OF #2 ENG OIL PRESSURE AND SHUT #2 ENG ON APCH TO MCI FOR CORRECTIVE MAINT ACTION. MAINT FOUND MAIN OIL PRESSURE XMITTER LINE LOOSE TIGHTENED AND PERFORMED ALL REQUIRED MAINT. ACFT WAS RELEASED FOR SVC. IT IS IN MY JUDGEMENT THAT SOME HUMAN FACTORS CONTRIBUTED TO THE EVENT. THE LOSS OF MY PARTNER FROM THE JOB DID MAKE ME UPSET AND AFTER REMOVING THE INCORRECT XMITTER; I WAS VERY DISCOURAGED AND SHOULD HAVE TAKEN A BREAK. TO MAKE UP FOR LOST TIME; I BEGAN TO RUSH JOB AND FAILED TO RECHK OIL LINES FOR PROPER TORQUE.