Narrative:

Left engine vibration trend spike 2 military and above. Fan lube was requested by power plant engineering. Lube was accomplished per maintenance manual 72-31-13. The mechanics that accomplished the task marked the parts at removal. As lead mechanic, I was not present for the entire job. I did see parts with marks and blades numbered. After reassembly, I was present for the vibration survey run. It was accomplished per maintenance manual 71-00-00 test 6. The peak vibration noted was 2.1 at takeoff power. The limit is 2.5 spikes above 2 military had been recorded in the trend data. The other mechanic and I felt the run was satisfactory based on the maintenance manual limits and trend data the aircraft was released for service. In-flight, the left engine vibration reached a peak of 3.4 military. After talking to engineering and the mechanic that accomplished the lube, we told engineering the first place we recommended to look would be the balance weight ring. This was recommended due to after handling of parts the markings were not as clearly defined. The corrective action was to reclock the weight ring. No engine damage was noted and aircraft continued in service with no further vibration problem that we are aware of.

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Original NASA ASRS Text

Title: A B757-200 RPTED L ENG HIGH VIBRATION AFTER A FAN BLADE LUBRICATION REPAIR CAUSED BY THE BAL WT RING POSITIONED INCORRECTLY.

Narrative: L ENG VIBRATION TREND SPIKE 2 MIL AND ABOVE. FAN LUBE WAS REQUESTED BY PWR PLANT ENGINEERING. LUBE WAS ACCOMPLISHED PER MAINT MANUAL 72-31-13. THE MECHS THAT ACCOMPLISHED THE TASK MARKED THE PARTS AT REMOVAL. AS LEAD MECH, I WAS NOT PRESENT FOR THE ENTIRE JOB. I DID SEE PARTS WITH MARKS AND BLADES NUMBERED. AFTER REASSEMBLY, I WAS PRESENT FOR THE VIBRATION SURVEY RUN. IT WAS ACCOMPLISHED PER MAINT MANUAL 71-00-00 TEST 6. THE PEAK VIBRATION NOTED WAS 2.1 AT TKOF PWR. THE LIMIT IS 2.5 SPIKES ABOVE 2 MIL HAD BEEN RECORDED IN THE TREND DATA. THE OTHER MECH AND I FELT THE RUN WAS SATISFACTORY BASED ON THE MAINT MANUAL LIMITS AND TREND DATA THE ACFT WAS RELEASED FOR SVC. INFLT, THE L ENG VIBRATION REACHED A PEAK OF 3.4 MIL. AFTER TALKING TO ENGINEERING AND THE MECH THAT ACCOMPLISHED THE LUBE, WE TOLD ENGINEERING THE FIRST PLACE WE RECOMMENDED TO LOOK WOULD BE THE BAL WT RING. THIS WAS RECOMMENDED DUE TO AFTER HANDLING OF PARTS THE MARKINGS WERE NOT AS CLRLY DEFINED. THE CORRECTIVE ACTION WAS TO RECLOCK THE WT RING. NO ENG DAMAGE WAS NOTED AND ACFT CONTINUED IN SVC WITH NO FURTHER VIBRATION PROB THAT WE ARE AWARE OF.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.