A LEAD TECHNICIAN RPTS RB-211 ENGS ON B757-200 ACR ACFT HAVING RADIAL SHAFT BEARING FAILURE AND SOME OPERATING WITH KNOWN SUSPECT BEARINGS.

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THIS IS IN REGARDS TO PART NUMBER WXXZ RADIAL DRIVE SHAFT ON THE RB-211 (B757 ACFT). FOR SOME TIME WE HAVE BEEN HAVING STEADY BEARING (WXXZ) FAILURES IN THE FIELD WHICH DEALT WITH A PARTICULAR LOT NUMBER OF BEARINGS. SINCE THEN THEY HAVE DISCOVERED THAT THIS PROB IS NOT RESTR TO THE LOT NUMBER; BUT ALL OF THE OLD PART NUMBERS. WHILE ACR IS TRYING VERY HARD TO GET THESE PARTS OFF WING; COMPANY X CANNOT SUPPLY THE AMOUNT OF NEW BEARINGS WXXZ TO ACR. MY CONCERN IS WE KNOW THAT WE HAVE A MINIMUM OF 30 SHAFT DRIVES ON WING THAT ARE SUBJECT TO THIS HIGH FAILURE RATE; AND I EMPHASIZE MINIMUM 30 SHAFTS. THE PROB IS; PER OUR MEETING ON OCT/TUE/00; THE ONLY THING WE ARE DOING IS CHKING THE OIL FILTER EVERY 85 HRS. UNFORTUNATELY; ONCE CONTAMINATION SHOWS UP IN THE FILTER IT'S TOO LATE AND THE BEARING HAS ALREADY FAILED. I HAVE SUGGESTED THAT THE SHAFTS ARE REMOVED ON OVERNIGHT CHKS AND THE BEARINGS ARE INSPECTED. THE CONCERN OUR ENGINEERING DEPT HAS IS WE MIGHT FIND A BAD ONE AND POSSIBLY HAVE AN ACFT ON GND. SO; THEY WOULD RATHER FLY AN ACFT WITH A BAD BEARING AND POSSIBLY AN INFLT SHUTDOWN THAN PARK AN ACFT. I MUST STRESS THAT WHEN THIS BEARING FAILS THE ENG IMMEDIATELY SHUTS DOWN; AND WE RECENTLY HAD THIS VERY THING HAPPEN WITH AN EMER LNDG IN XXX. ALSO; WE HAVE AN ACFT THAT A SHAFT WAS REMOVED FROM THE #2 ENG. THIS BEARING HAS CONTAMINATED THIS ENG WITH 4 STEEL RIVETS AND AN UNKNOWN AMOUNT OF METAL FROM THE DETERIORATING BEARING CAGE. I WAS TOLD BY ACR ENGINEERING THAT THEY ARE NOT CONCERNED WITH CONTAMINATION IN THE ENG. FURTHERMORE; THE OTHER ENG ON THE SAME IS FLYING WITH A KNOWN BAD BEARING. MY POINT BEING THAT THIS ACFT IS IN SVC WITH TWO HIGH SUSPECT FAILURE ENGS.