Narrative:

We took an approximate 50 min delay due to an open write up for 'broken armrest.' the weather was rapidly improving from cat 2/3 ops in sn and fzfg on the inbound flight; to no precipitation and 2-3 miles visibility by the end of the deicing procedure. The deice/anti-ice was performed on the remote pad west of the terminal with both engines at idle and engine ai 'on'.during the outbound taxi for the runway; we performed an engines run-up to 70% N1 per vol 2 ground ops in icing conditions. The engine#1 N1 vib indicated 6.9 units advisory (pulsating green). We decided to continue taxiing to the runway and to perform another run-up before lining up for takeoff. The second acceleration to 70% N1 confirmed abnormal engine#1 N1 vib around 6.4 units. We notified the dispatch and maintenance. After brief research maintenance directed us to return to the gate. The post flight inspection was performed by the first officer (first officer) and the mechanic. Both reported no damage and the engines clear of any ice; snow or frost. Engine fan rotation was normal.the contract mechanic informed me that maintenance asked him to sign off the aircraft for flight; per provision of trouble shooting manual (tsm). The note in question stated that if the crew observes advisory N1 vib > 6.0 units for less than one minute; it would be ok to continue. I asked them how they came to a conclusion that the abnormal vib were observed for less than a minute. I explained that we accelerated the engines to 70% N1 for 30 sec only; per ground ops in icing conditions policy. The maintenance did not recommend a longer engine run-up before returning us to the gate. The statement that the abnormality was observed for less than a minute was simply wishful thinking; rather than an actual fact. I suggested that a longer engine run-up test should be performed to establish factual base for utilizing this tsm provision. The maintenance did not accept my suggestion and I decided to involve the duty manager. After brief discussion maintenance agreed with my position that an engine test should be a prudent solution under the circumstances. At the same time; the contract mechanic approached me and informed me that maintenance had agreed to the engine test.the maintenance did not specify any requirements for the test procedure. The contract mechanic; first officer and I established a plan to taxi to a safe area; clear of ice and snow and accelerate the engines to 70% N1 for more than a minute. If the N1 vib dropped below 6.0 units at any time during this 1min interval; we would consider it a successful test. If N1 vib were above 6.0 units for a full minute; then it would be considered a failed test.the ATC cleared us to taxi and to find a clear spot on east; at least 1000ft south of G. I performed the engines run-up; concentrating my attention primarily outside considering the current icy conditions. The first officer and the mechanic tracked the test progress. The engine #1 N1 vib moved above 6.0 units after the engine reached above 50% N1 acceleration. At 70% N1; the N1 vib oscillated in the range 6.3-6.5 units for a full minute. We stopped the test at 70 seconds; after agreeing we had a failed test on engine#1 N1 vib indications. The engine#2 N1 vib was in the range 0.0--0.1 units at all times.back at the gate; the mechanic initiated a phone call with maintenance to inform them of the test outcome. I notified dispatch and scheduling about the current situation. A few minutes later I was informed by maintenance via phone; that everything was alright and we would be placed on tear down inspection (tdi). I asked him if he was aware that the engine failed the test. He was not aware and he was rather confused. A few minutes later I received a phone call from maintenance and was told that even though the engine test failed; there is another note in tsm allowing the aircraft to be dispatched under a tdi with the current levels of N1 vib. I told him that I respectfully disagree and that his statement is just anotherwishful conclusion; rather than a factual statement. The engine test showed a progressive relation between the N1 rotation speed and the N1 vib indications. We performed the testing at 70% N1 where we observed 6.3-6.5 unit vibrations. Under the current surface conditions we would be performing a toga takeoff; where the N1 vib may reach progressively higher indications. I asked him if he could give me any guidance as to what value of N1 vib I should consider the limit in my decision to continue or abort the takeoff; especially under the current surface conditions. He was not able to give me a response; but instead insisted that the tsm is written by airbus based on extensive evaluations. He stated that it is approved by the FAA and the company so I should comply with it. Based on his tone I perceived this statement as an intimidation tactic; and I informed him that I have to take my own decision based on the current conditions and circumstances. In a subsequent call from dispatch I was told that the aircraft was signed off and good to fly; and I should board the passengers. I attempted to explain my position but quickly realized he was more go oriented; rather than concerned for safety. I informed him that I am exercising my authority as pilot in command and I will not continue this flight under the current conditions and circumstances; due to serious safety concerns. I also informed the duty manager about my decision. He stated his support.I based my decision on the following:1.the maintenance guidance was inconsistent; sporadic and contradicting. They were clearly go oriented - wishfully fabricating time and vibration values with no factual grounds; looking into bite-size notes from tsm one at a time. Earlier in the day after I was placed on hold with maintenance for 10-15 minutes (because of the broken armrest write-up) I was warned by dispatch that maintenance has been overwhelmed the whole day. They were clearly operating behind the curve and under some form of deficiency.2. A quick review of the QRH high engine vibration 70.26 (if icing is not suspected) directs a thrust reduction if flight conditions permit. The procedure is designed for predominantly inflight guidance but a reduced performance shortfall can be reasonably expected during the takeoff phase. Initiating takeoff with this knowledge would be in direct violation of the limitations section.3. There was no defined guidance as to what value of N1 vib should be considered in a go/no go decision scenario when the thrust levers are advanced to toga position. The crew was building fatigue after the previous CAT 2/3 ops; long taxiing on a slippery ramp and contaminated runway and taxiways under limited support (the station had no radio and was short staffed; which created substantial issues and additional maneuvering onto an icy ramp during the initial parking and the subsequent btb).4. We taxied twice on the full length of the runway that night. A probable high energy abort would have been an extremely dangerous maneuver on these surface conditions. Dispatch and scheduling were informed about my decision. We were released from duty [soon after]. Due to transportation and hotel issues we reached our rooms [late]. The passengers were kept at the gate for a long time; which at one point led to law enforcement intervention. On our way out of the airport we had to navigate around stranded and angry passengers. While I was trying to find transportation to the hotel; the first officer and flight attendants were attempting to help the disabled passengers and anyone in need for almost an hour. The whole crew behaved professionally and with dignity beyond their duty call. A few of my crew members were not dressed properly for the weather conditions and we were all unable to eat that night.another serious safety concern for me was the fact that the aircraft log book was currently signed-off under tdi provision. The next crew flying the airplane would not have any information regarding the specifics of the event that occurred. I voiced this concern to maintenance and the duty manager. Captain adam lake informed me that in such a case; where there is disagreement between a pilot and maintenance; maintenance will readdress the write-up before the next flight.

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Original NASA ASRS Text

Title: A320 Captain reported a vibration issue with one engine and subsequent refusal of the aircraft for flight.

Narrative: We took an approximate 50 min delay due to an open write up for 'broken armrest.' The weather was rapidly improving from Cat 2/3 ops in SN and FZFG on the inbound flight; to no precipitation and 2-3 miles visibility by the end of the deicing procedure. The Deice/Anti-ice was performed on the remote pad west of the terminal with both engines at idle and ENG AI 'ON'.During the outbound taxi for the runway; we performed an engines run-up to 70% N1 per Vol 2 Ground Ops in Icing Conditions. The ENG#1 N1 VIB indicated 6.9 units advisory (pulsating green). We decided to continue taxiing to the runway and to perform another run-up before lining up for takeoff. The second acceleration to 70% N1 confirmed abnormal ENG#1 N1 VIB around 6.4 units. We notified the Dispatch and Maintenance. After brief research Maintenance directed us to return to the gate. The post flight inspection was performed by the First Officer (FO) and the Mechanic. Both reported no damage and the engines clear of any ice; snow or frost. Engine fan rotation was normal.The Contract Mechanic informed me that Maintenance asked him to sign off the aircraft for flight; per provision of Trouble Shooting Manual (TSM). The note in question stated that if the crew observes advisory N1 VIB > 6.0 units for less than one minute; it would be OK to continue. I asked them how they came to a conclusion that the abnormal VIB were observed for less than a minute. I explained that we accelerated the engines to 70% N1 for 30 sec only; per Ground Ops in Icing Conditions policy. The Maintenance did not recommend a longer engine run-up before returning us to the gate. The statement that the abnormality was observed for less than a minute was simply wishful thinking; rather than an actual fact. I suggested that a longer engine run-up test should be performed to establish factual base for utilizing this TSM provision. The Maintenance did not accept my suggestion and I decided to involve the Duty Manager. After brief discussion Maintenance agreed with my position that an engine test should be a prudent solution under the circumstances. At the same time; the Contract Mechanic approached me and informed me that Maintenance had agreed to the engine test.The Maintenance did not specify any requirements for the test procedure. The Contract Mechanic; FO and I established a plan to taxi to a safe area; clear of ice and snow and accelerate the engines to 70% N1 for more than a minute. If the N1 VIB dropped below 6.0 units at any time during this 1min interval; we would consider it a successful test. If N1 VIB were above 6.0 units for a full minute; then it would be considered a failed test.The ATC cleared us to taxi and to find a clear spot on E; at least 1000ft south of G. I performed the engines run-up; concentrating my attention primarily outside considering the current icy conditions. The FO and the Mechanic tracked the test progress. The ENG #1 N1 VIB moved above 6.0 units after the engine reached above 50% N1 acceleration. At 70% N1; the N1 VIB oscillated in the range 6.3-6.5 units for a full minute. We stopped the test at 70 seconds; after agreeing we had a failed test on ENG#1 N1 VIB indications. The ENG#2 N1 VIB was in the range 0.0--0.1 units at all times.Back at the gate; the Mechanic initiated a phone call with Maintenance to inform them of the test outcome. I notified Dispatch and Scheduling about the current situation. A few minutes later I was informed by Maintenance via phone; that everything was alright and we would be placed on TEAR DOWN INSPECTION (TDI). I asked him if he was aware that the engine failed the test. He was not aware and he was rather confused. A few minutes later I received a phone call from Maintenance and was told that even though the engine test failed; there is another note in TSM allowing the aircraft to be dispatched under a TDI with the current levels of N1 VIB. I told him that I respectfully disagree and that his statement is just anotherwishful conclusion; rather than a factual statement. The engine test showed a progressive relation between the N1 rotation speed and the N1 VIB indications. We performed the testing at 70% N1 where we observed 6.3-6.5 unit vibrations. Under the current surface conditions we would be performing a TOGA takeoff; where the N1 VIB may reach progressively higher indications. I asked him if he could give me any guidance as to what value of N1 VIB I should consider the limit in my decision to continue or abort the takeoff; especially under the current surface conditions. He was not able to give me a response; but instead insisted that the TSM is written by Airbus based on extensive evaluations. He stated that it is approved by the FAA and the company so I should comply with it. Based on his tone I perceived this statement as an intimidation tactic; and I informed him that I have to take my own decision based on the current conditions and circumstances. In a subsequent call from Dispatch I was told that the aircraft was signed off and good to fly; and I should board the passengers. I attempted to explain my position but quickly realized he was more GO oriented; rather than concerned for safety. I informed him that I am exercising my authority as Pilot in Command and I will not continue this flight under the current conditions and circumstances; due to serious safety concerns. I also informed the Duty Manager about my decision. He stated his support.I based my decision on the following:1.The Maintenance guidance was inconsistent; sporadic and contradicting. They were clearly GO oriented - wishfully fabricating time and vibration values with no factual grounds; looking into bite-size notes from TSM one at a time. Earlier in the day after I was placed on hold with Maintenance for 10-15 minutes (because of the broken armrest write-up) I was warned by Dispatch that Maintenance has been overwhelmed the whole day. They were clearly operating behind the curve and under some form of deficiency.2. A quick review of the QRH High Engine Vibration 70.26 (if icing is not suspected) directs a thrust reduction if flight conditions permit. The procedure is designed for predominantly inflight guidance but a reduced performance shortfall can be reasonably expected during the takeoff phase. Initiating takeoff with this knowledge would be in direct violation of the Limitations Section.3. There was no defined guidance as to what value of N1 VIB should be considered in a GO/NO GO decision scenario when the thrust levers are advanced to TOGA position. The crew was building fatigue after the previous CAT 2/3 Ops; long taxiing on a slippery ramp and contaminated Runway and Taxiways under limited support (the station had no radio and was short staffed; which created substantial issues and additional maneuvering onto an icy ramp during the initial parking and the subsequent BTB).4. We taxied twice on the full length of the Runway that night. A probable high energy abort would have been an extremely dangerous maneuver on these surface conditions. Dispatch and Scheduling were informed about my decision. We were released from duty [soon after]. Due to transportation and hotel issues we reached our rooms [late]. The passengers were kept at the gate for a long time; which at one point led to law enforcement intervention. On our way out of the airport we had to navigate around stranded and angry passengers. While I was trying to find transportation to the hotel; the FO and Flight Attendants were attempting to help the disabled passengers and anyone in need for almost an hour. The whole crew behaved professionally and with dignity beyond their duty call. A few of my crew members were not dressed properly for the weather conditions and we were all unable to eat that night.Another serious safety concern for me was the fact that the aircraft log book was currently signed-off under TDI provision. The next crew flying the airplane would not have any information regarding the specifics of the event that occurred. I voiced this concern to Maintenance and the Duty Manager. Captain Adam Lake informed me that in such a case; where there is disagreement between a pilot and Maintenance; Maintenance will readdress the write-up before the next flight.

Data retrieved from NASA's ASRS site 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.