Narrative:

#2 engine vibration. Accepted engine inlet and exhaust inspection and check of 7 each chip detectors per maintenance manual. No defects found. Maintenance partner contacted line maintenance engine maintenance coordinator and he wanted log item signed off as acceptable check, and a line maintenance callout to follow to change engine. We were uncomfortable with this 'fix' and called back and after further discussion decided to take aircraft for a maintenance power run. Maintenance partner and I accepted a power assurance run with all indications normal. #2 engine was increased to 1.375 EPR which resulted in a higher 3.6 vibrations of N1. The aircraft returned to the gate where the engine maintenance controller was contacted again and he agreed that the vibrations were high but the item could be signed off per the maintenance manual and run-up handbook and an item would follow that he would input to change the engine next maintenance opportunity without disrupting the aircraft schedule. Callback conversation with reporter revealed the following information: inbound air carrier flight crew reported vibrations exceeding their limitations of 3.0 units. Mechanic could not find maintenance limits in run-up handbook. He felt that engine was within limits even though he was uncomfortable with vibration, so he released the aircraft. After the aircraft had departed the mechanic received a call from line maintenance controller and learned that it had exceeded limitations. A couple of days later, an 'advance' revision increased limits to 5 units. Now, the engine vibration was within limits. Reporter states that airbus industries is working with customers to resolve excessive engine vibration problem. The A320 does not operate through reporter's maintenance base often enough for him to feel educated. The limitations were, however, easily accessible and reporter simply made a mistake.

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Original NASA ASRS Text

Title: ACR MAINT RELEASED AN ACFT TO SVC WITH ENG VIBRATION.

Narrative: #2 ENG VIBRATION. ACCEPTED ENG INLET AND EXHAUST INSPECTION AND CHK OF 7 EACH CHIP DETECTORS PER MAINT MANUAL. NO DEFECTS FOUND. MAINT PARTNER CONTACTED LINE MAINT ENG MAINT COORDINATOR AND HE WANTED LOG ITEM SIGNED OFF AS ACCEPTABLE CHK, AND A LINE MAINT CALLOUT TO FOLLOW TO CHANGE ENG. WE WERE UNCOMFORTABLE WITH THIS 'FIX' AND CALLED BACK AND AFTER FURTHER DISCUSSION DECIDED TO TAKE ACFT FOR A MAINT PWR RUN. MAINT PARTNER AND I ACCEPTED A PWR ASSURANCE RUN WITH ALL INDICATIONS NORMAL. #2 ENG WAS INCREASED TO 1.375 EPR WHICH RESULTED IN A HIGHER 3.6 VIBRATIONS OF N1. THE ACFT RETURNED TO THE GATE WHERE THE ENG MAINT CTLR WAS CONTACTED AGAIN AND HE AGREED THAT THE VIBRATIONS WERE HIGH BUT THE ITEM COULD BE SIGNED OFF PER THE MAINT MANUAL AND RUN-UP HANDBOOK AND AN ITEM WOULD FOLLOW THAT HE WOULD INPUT TO CHANGE THE ENG NEXT MAINT OPPORTUNITY WITHOUT DISRUPTING THE ACFT SCHEDULE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: INBOUND ACR FLC RPTED VIBRATIONS EXCEEDING THEIR LIMITATIONS OF 3.0 UNITS. MECH COULD NOT FIND MAINT LIMITS IN RUN-UP HANDBOOK. HE FELT THAT ENG WAS WITHIN LIMITS EVEN THOUGH HE WAS UNCOMFORTABLE WITH VIBRATION, SO HE RELEASED THE ACFT. AFTER THE ACFT HAD DEPARTED THE MECH RECEIVED A CALL FROM LINE MAINT CTLR AND LEARNED THAT IT HAD EXCEEDED LIMITATIONS. A COUPLE OF DAYS LATER, AN 'ADVANCE' REVISION INCREASED LIMITS TO 5 UNITS. NOW, THE ENG VIBRATION WAS WITHIN LIMITS. RPTR STATES THAT AIRBUS INDUSTRIES IS WORKING WITH CUSTOMERS TO RESOLVE EXCESSIVE ENG VIBRATION PROB. THE A320 DOES NOT OPERATE THROUGH RPTR'S MAINT BASE OFTEN ENOUGH FOR HIM TO FEEL EDUCATED. THE LIMITATIONS WERE, HOWEVER, EASILY ACCESSIBLE AND RPTR SIMPLY MADE A MISTAKE.

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.