A B747-200 WAS DISPATCHED WITH THE #4 ENG PNEUMATIC SYS AND THE ENG ANTI-ICE SYS INOP DUE TO THE WRONG VALVE RENDERED INOP AND DEFERRED.

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IN SUM: I WAS INFORMED BY MY SUPVR THAT I MADE A MISTAKE OF INOPING THE WRONG VALVE; INSTEAD OF THE HIGH PRESSURE BLEED VALVE I INOPED THE PRESSURE REGULATING VALVE ON #4 ENG OF AIRLINES B747-200. ESTIMATED GND TIME WAS LESS THAN 2 HRS TURN AROUND. THIS IS WHAT HAPPENED IN THIS EVENT. I AM AN AIRLINE MECH. I AND ANOTHER MECH WERE ASSIGNED TO RECEIVE; WORK AND DISPATCH THIS ACFT ON NOV/ZZ/96. BESIDES DOING PREFLT CHKS; GND HANDLING; FUELING AND SVCING WE HAD 4 LOG WRITE-UPS FROM THE ACFT THAT NEEDED WORK. ONE OF THE WRITE-UPS REQUIRED WAS TO INOP THE #4 ENG HIGH STAGE BLEED VALVE. I FINISHED OILING THE ENGS AND WENT TO THE COCKPIT. MY LEAD MAN WAS READING THE LOGBOOK AND TOLD ME TO OPEN THE #4 ENG L INBOARD COWLING TO INOP THE HIGH STAGE BLEED VALVE. I WENT DOWN AND OPENED THE #4 ENG COWLING. AFTER I OPENED THE #4 ENG I WENT BACK TO THE OFFICE AND STARTED LOOKING THROUGH THE MAINT MANUAL BECAUSE I DIDN'T KNOW WHERE THE VALVE WAS LOCATED ON THE ENG. MY LEAD FOLLOWED ME INTO THE OFFICE AND ASKED ME WHAT I WAS DOING AND I TOLD HIM I WAS TRYING TO LOCATE THE VALVE. THE LEAD HAD ALREADY POINTED OUT THE LOCATION OF THE VALVE TO THE OTHER MECH. I ASKED THE OTHER MECH IF HE KNEW THE VALVE LOCATION. HE SAID YES AND HELD THE VALVE. I REPEATED TO HIM; ARE YOU SURE THAT IS THE CORRECT VALVE? HE SAID THE LEAD TOLD HIM IT WAS THE CORRECT VALVE. AFTER THE VALVE WAS INOPED WE CLOSED UP THE ENG. IT WAS IN XXX WHEN IT WAS DISCOVERED THE WRONG VALVE WAS INOPED CLOSED. IT WAS NOT CORRECTED; BUT LEFT OPEN TO AVOID ANY DELAY. ON FINAL APCH TO THE TERMINATING STATION THE FLC COULD NOT GET #4 ENG ANTI-ICE. THE AIRPLANE LANDED SAFELY AT THE ARPT. THERE WAS NO OTHER DISCREPANCY RPTED ON THE ENG OR AIRPLANE.