Narrative:

Upon arrival at the gate; we met the inbound pilots and were briefed on our aircraft's maintenance status. The captain spoke of a high frequency vibration that was felt in the cockpit. The vibration was described as being most prominent during climb out at about 230 KTS and diminishing when the speed was increased and was least apparent during cruise. The vibration then intensified during the descent into sfo. The inbound captain indicated the aircraft was lightly loaded and never went faster than 280 KTS. The flight conditions were reported as smooth air throughout the flight. The inbound captain and I discussed the characteristics of vertical bounce as described by the flight manual and agreed that the vibration felt was not indicative of vertical bounce. The inbound captain was disconcerted about the vibration and indicated that if he were going on with this aircraft he would not accept it. I then proceeded to query the gate mechanics that the inbound captain had briefed; and discussed the vibration inspection procedures and the time required to accomplish the inspection. The mechanic said that a cursory inspection would take place that would last approximately 30 mins. This inspection would look for any obvious mechanical discrepancies that might cause a vibration. If nothing were found; it would be prudent to conduct a more extensive inspection that may include checking the flight control riggings; cables and pulleys and the sort. This inspection could last up to 5 or 6 hours and may include a test flight by a test pilot. At this point I felt like I did not have enough information to make a safe go or no go decision to accept the aircraft. I asked the mechanics to proceed with the cursory inspection. About 30 mins after the commencement of the initial inspection; a mechanic supervisor came up to the cabin and told me that everything checks out and the aircraft is fine and he is going to sign off the vibration discrepancy. I then asked the supervisor what they found to be the vibration causing anomaly. He replied they did not find a thing and we were good to go. I then asked him if the mechanics performed the complete vibration troubleshooting procedure; he responded that it was all done and everything checks out good. I told the supervisor that I was under the impression that the vibration procedure would take at least 30-40 mins to complete; and if they found nothing; that would prompt a more thorough inspection lasting hours. He replied that everything was fine. At this point I got suspicious and asked him if I could talk to the line mechanics who performed the inspection to gain more insight on what they found. Both the supervisor and I proceeded down to the ramp to chat with the mechanics. The mechanics indicated that they indeed accomplished the cursory inspection and did not find a thing. They said that simply means that there could still be a problem lurking deeper in the aircraft and the cursory inspection had not revealed it or there could be nothing wrong with the aircraft. So; with the knowledge of a possible problem yet to be revealed or not and the input from an inbound captain; I felt the aircraft vibration needed to be explored more than just a cursory inspection. I elected to reject the aircraft until someone could assure me that it was actually free of defects and safe for flight. The supervisor informed me that my refusal of the aircraft would take it OTS and would be a time consuming affair. I responded to his comment by informing him that he could not produce any evidence that my aircraft is safe and ready for passenger service; nor could he provide any helpful information in order for me to make a good safe decision to accept the aircraft. After a few mins of taking care of passenger's questions at the gate and informing dispatch; zone and the flight attendants; I received a call moments later from a flight duty manager who inquired why I turned down an aircraft that had been signed off as defect free. This surprised me that the aircraft was signed off after I had refused it; without further maintenance action. This immediate phone call indicated to me that maintenance had disregarded my concerns about the vibration. I should have recorded why the aircraft was refused in an infoonly write-up; that way if the aircraft was passed along to the next crew they would have been informed as to the nature of the situation. After then talking to the crew desk for a reassignment which was to depart sfo at XA55 to ZZZ; we discovered after pulling the paperwork that we were assigned the same aircraft with the vibration problem. The log history indicated that the vibration had been checked and everything was normal; there were no open write-ups. I would guess an hour had passed since I refused the aircraft the first time; not enough time to further investigate the vibration problem according to the line mechanics. After discovering the aircraft assignment I made a courtesy call to the flight duty manager to let him know that I intended to refuse the aircraft again if there was not sufficient evidence of a safe aircraft. I also called maintenance control to get an idea of what if anything was done since. Maintenance control indicated that the aircraft was scheduled to go out for a test flight before the ZZZ flight. Again the paperwork did not indicate any problems or the need for the test flight. I kept in regular contact with maintenance control as to the progress of the test flight and was informed that a vibration was found and an adjustment was made. I asked for details and only received vague answers as to the nature of the problem. I also asked if the test pilots could give me a call to brief me but no call was ever received. Maintenance control also said that another problem was discovered on the test flight and would be repaired at the gate. The aircraft was delivered to the gate with a confign warning system inoperative. The mechanics said the fix would take 45 mins to get the parts; repair then test. About a half hour into the repair; our duty day and fatigue was becoming a factor. At XB30 west coast; I gave the crew desk a courtesy call to let them know that we were running out of duty day if the aircraft was not fixed in an hour. Maybe they could start to look at other contingencies like a reassignment or a plane change to complete the flight. Our report time indicated we were good for 12:30 duty day or until XE30 west coast time. The ZZZ flight was about 2 hours in duration; so we needed to be on our way at XC30 local. At around XC00 after talking to the mechanics; they indicated that we could start to board passenger and they would be ready to go shortly. At XC20 the mechanics informed me that the aircraft was still not fixed; the problem turned out to be something more complex and that they had no idea what was wrong with it. At XC30 local; I contacted the crew desk to see if they had a plan developed yet to get our passenger to ZZZ. No plan had been concocted and they said they were told by the maintenance supervisor that the aircraft would be ready in 15 mins. That was clearly not the case when I spoke to the mechanics again. The line mechanics indicated that it could be 2 or 3 hours. I relayed this information back to the crew desk and told her that we were calling it quits due to fatigue and our duty day was gone. I returned to the aircraft and made a PA to inform our passenger of the cancellation of their flight due to our ongoing maintenance problem and the crew duty day. I personally apologized to each passenger as they left the aircraft.

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Original NASA ASRS Text

Title: A B737-300 CAPT IS CONCERNED DURING PREFLIGHT ABOUT A VIBRATION WRITE-UP. MAINT WORKS ON THE ACFT UNTIL THE FLT CREW RUNS OUT OF DUTY TIME.

Narrative: UPON ARR AT THE GATE; WE MET THE INBOUND PLTS AND WERE BRIEFED ON OUR ACFT'S MAINT STATUS. THE CAPT SPOKE OF A HIGH FREQ VIBRATION THAT WAS FELT IN THE COCKPIT. THE VIBRATION WAS DESCRIBED AS BEING MOST PROMINENT DURING CLBOUT AT ABOUT 230 KTS AND DIMINISHING WHEN THE SPD WAS INCREASED AND WAS LEAST APPARENT DURING CRUISE. THE VIBRATION THEN INTENSIFIED DURING THE DSCNT INTO SFO. THE INBOUND CAPT INDICATED THE ACFT WAS LIGHTLY LOADED AND NEVER WENT FASTER THAN 280 KTS. THE FLT CONDITIONS WERE RPTED AS SMOOTH AIR THROUGHOUT THE FLT. THE INBOUND CAPT AND I DISCUSSED THE CHARACTERISTICS OF VERT BOUNCE AS DESCRIBED BY THE FLT MANUAL AND AGREED THAT THE VIBRATION FELT WAS NOT INDICATIVE OF VERT BOUNCE. THE INBOUND CAPT WAS DISCONCERTED ABOUT THE VIBRATION AND INDICATED THAT IF HE WERE GOING ON WITH THIS ACFT HE WOULD NOT ACCEPT IT. I THEN PROCEEDED TO QUERY THE GATE MECHS THAT THE INBOUND CAPT HAD BRIEFED; AND DISCUSSED THE VIBRATION INSPECTION PROCS AND THE TIME REQUIRED TO ACCOMPLISH THE INSPECTION. THE MECH SAID THAT A CURSORY INSPECTION WOULD TAKE PLACE THAT WOULD LAST APPROX 30 MINS. THIS INSPECTION WOULD LOOK FOR ANY OBVIOUS MECHANICAL DISCREPANCIES THAT MIGHT CAUSE A VIBRATION. IF NOTHING WERE FOUND; IT WOULD BE PRUDENT TO CONDUCT A MORE EXTENSIVE INSPECTION THAT MAY INCLUDE CHKING THE FLT CTL RIGGINGS; CABLES AND PULLEYS AND THE SORT. THIS INSPECTION COULD LAST UP TO 5 OR 6 HRS AND MAY INCLUDE A TEST FLT BY A TEST PLT. AT THIS POINT I FELT LIKE I DID NOT HAVE ENOUGH INFO TO MAKE A SAFE GO OR NO GO DECISION TO ACCEPT THE ACFT. I ASKED THE MECHS TO PROCEED WITH THE CURSORY INSPECTION. ABOUT 30 MINS AFTER THE COMMENCEMENT OF THE INITIAL INSPECTION; A MECH SUPVR CAME UP TO THE CABIN AND TOLD ME THAT EVERYTHING CHKS OUT AND THE ACFT IS FINE AND HE IS GOING TO SIGN OFF THE VIBRATION DISCREPANCY. I THEN ASKED THE SUPVR WHAT THEY FOUND TO BE THE VIBRATION CAUSING ANOMALY. HE REPLIED THEY DID NOT FIND A THING AND WE WERE GOOD TO GO. I THEN ASKED HIM IF THE MECHS PERFORMED THE COMPLETE VIBRATION TROUBLESHOOTING PROC; HE RESPONDED THAT IT WAS ALL DONE AND EVERYTHING CHKS OUT GOOD. I TOLD THE SUPVR THAT I WAS UNDER THE IMPRESSION THAT THE VIBRATION PROC WOULD TAKE AT LEAST 30-40 MINS TO COMPLETE; AND IF THEY FOUND NOTHING; THAT WOULD PROMPT A MORE THOROUGH INSPECTION LASTING HRS. HE REPLIED THAT EVERYTHING WAS FINE. AT THIS POINT I GOT SUSPICIOUS AND ASKED HIM IF I COULD TALK TO THE LINE MECHS WHO PERFORMED THE INSPECTION TO GAIN MORE INSIGHT ON WHAT THEY FOUND. BOTH THE SUPVR AND I PROCEEDED DOWN TO THE RAMP TO CHAT WITH THE MECHS. THE MECHS INDICATED THAT THEY INDEED ACCOMPLISHED THE CURSORY INSPECTION AND DID NOT FIND A THING. THEY SAID THAT SIMPLY MEANS THAT THERE COULD STILL BE A PROB LURKING DEEPER IN THE ACFT AND THE CURSORY INSPECTION HAD NOT REVEALED IT OR THERE COULD BE NOTHING WRONG WITH THE ACFT. SO; WITH THE KNOWLEDGE OF A POSSIBLE PROB YET TO BE REVEALED OR NOT AND THE INPUT FROM AN INBOUND CAPT; I FELT THE ACFT VIBRATION NEEDED TO BE EXPLORED MORE THAN JUST A CURSORY INSPECTION. I ELECTED TO REJECT THE ACFT UNTIL SOMEONE COULD ASSURE ME THAT IT WAS ACTUALLY FREE OF DEFECTS AND SAFE FOR FLT. THE SUPVR INFORMED ME THAT MY REFUSAL OF THE ACFT WOULD TAKE IT OTS AND WOULD BE A TIME CONSUMING AFFAIR. I RESPONDED TO HIS COMMENT BY INFORMING HIM THAT HE COULD NOT PRODUCE ANY EVIDENCE THAT MY ACFT IS SAFE AND READY FOR PAX SVC; NOR COULD HE PROVIDE ANY HELPFUL INFO IN ORDER FOR ME TO MAKE A GOOD SAFE DECISION TO ACCEPT THE ACFT. AFTER A FEW MINS OF TAKING CARE OF PAX'S QUESTIONS AT THE GATE AND INFORMING DISPATCH; ZONE AND THE FLT ATTENDANTS; I RECEIVED A CALL MOMENTS LATER FROM A FLT DUTY MGR WHO INQUIRED WHY I TURNED DOWN AN ACFT THAT HAD BEEN SIGNED OFF AS DEFECT FREE. THIS SURPRISED ME THAT THE ACFT WAS SIGNED OFF AFTER I HAD REFUSED IT; WITHOUT FURTHER MAINT ACTION. THIS IMMEDIATE PHONE CALL INDICATED TO ME THAT MAINT HAD DISREGARDED MY CONCERNS ABOUT THE VIBRATION. I SHOULD HAVE RECORDED WHY THE ACFT WAS REFUSED IN AN INFOONLY WRITE-UP; THAT WAY IF THE ACFT WAS PASSED ALONG TO THE NEXT CREW THEY WOULD HAVE BEEN INFORMED AS TO THE NATURE OF THE SITUATION. AFTER THEN TALKING TO THE CREW DESK FOR A REASSIGNMENT WHICH WAS TO DEPART SFO AT XA55 TO ZZZ; WE DISCOVERED AFTER PULLING THE PAPERWORK THAT WE WERE ASSIGNED THE SAME ACFT WITH THE VIBRATION PROB. THE LOG HISTORY INDICATED THAT THE VIBRATION HAD BEEN CHKED AND EVERYTHING WAS NORMAL; THERE WERE NO OPEN WRITE-UPS. I WOULD GUESS AN HR HAD PASSED SINCE I REFUSED THE ACFT THE FIRST TIME; NOT ENOUGH TIME TO FURTHER INVESTIGATE THE VIBRATION PROB ACCORDING TO THE LINE MECHS. AFTER DISCOVERING THE ACFT ASSIGNMENT I MADE A COURTESY CALL TO THE FLT DUTY MGR TO LET HIM KNOW THAT I INTENDED TO REFUSE THE ACFT AGAIN IF THERE WAS NOT SUFFICIENT EVIDENCE OF A SAFE ACFT. I ALSO CALLED MAINT CTL TO GET AN IDEA OF WHAT IF ANYTHING WAS DONE SINCE. MAINT CTL INDICATED THAT THE ACFT WAS SCHEDULED TO GO OUT FOR A TEST FLT BEFORE THE ZZZ FLT. AGAIN THE PAPERWORK DID NOT INDICATE ANY PROBS OR THE NEED FOR THE TEST FLT. I KEPT IN REGULAR CONTACT WITH MAINT CTL AS TO THE PROGRESS OF THE TEST FLT AND WAS INFORMED THAT A VIBRATION WAS FOUND AND AN ADJUSTMENT WAS MADE. I ASKED FOR DETAILS AND ONLY RECEIVED VAGUE ANSWERS AS TO THE NATURE OF THE PROB. I ALSO ASKED IF THE TEST PLTS COULD GIVE ME A CALL TO BRIEF ME BUT NO CALL WAS EVER RECEIVED. MAINT CTL ALSO SAID THAT ANOTHER PROB WAS DISCOVERED ON THE TEST FLT AND WOULD BE REPAIRED AT THE GATE. THE ACFT WAS DELIVERED TO THE GATE WITH A CONFIGN WARNING SYS INOP. THE MECHS SAID THE FIX WOULD TAKE 45 MINS TO GET THE PARTS; REPAIR THEN TEST. ABOUT A HALF HR INTO THE REPAIR; OUR DUTY DAY AND FATIGUE WAS BECOMING A FACTOR. AT XB30 WEST COAST; I GAVE THE CREW DESK A COURTESY CALL TO LET THEM KNOW THAT WE WERE RUNNING OUT OF DUTY DAY IF THE ACFT WAS NOT FIXED IN AN HR. MAYBE THEY COULD START TO LOOK AT OTHER CONTINGENCIES LIKE A REASSIGNMENT OR A PLANE CHANGE TO COMPLETE THE FLT. OUR RPT TIME INDICATED WE WERE GOOD FOR 12:30 DUTY DAY OR UNTIL XE30 WEST COAST TIME. THE ZZZ FLT WAS ABOUT 2 HRS IN DURATION; SO WE NEEDED TO BE ON OUR WAY AT XC30 LCL. AT AROUND XC00 AFTER TALKING TO THE MECHS; THEY INDICATED THAT WE COULD START TO BOARD PAX AND THEY WOULD BE READY TO GO SHORTLY. AT XC20 THE MECHS INFORMED ME THAT THE ACFT WAS STILL NOT FIXED; THE PROB TURNED OUT TO BE SOMETHING MORE COMPLEX AND THAT THEY HAD NO IDEA WHAT WAS WRONG WITH IT. AT XC30 LCL; I CONTACTED THE CREW DESK TO SEE IF THEY HAD A PLAN DEVELOPED YET TO GET OUR PAX TO ZZZ. NO PLAN HAD BEEN CONCOCTED AND THEY SAID THEY WERE TOLD BY THE MAINT SUPVR THAT THE ACFT WOULD BE READY IN 15 MINS. THAT WAS CLRLY NOT THE CASE WHEN I SPOKE TO THE MECHS AGAIN. THE LINE MECHS INDICATED THAT IT COULD BE 2 OR 3 HRS. I RELAYED THIS INFO BACK TO THE CREW DESK AND TOLD HER THAT WE WERE CALLING IT QUITS DUE TO FATIGUE AND OUR DUTY DAY WAS GONE. I RETURNED TO THE ACFT AND MADE A PA TO INFORM OUR PAX OF THE CANCELLATION OF THEIR FLT DUE TO OUR ONGOING MAINT PROB AND THE CREW DUTY DAY. I PERSONALLY APOLOGIZED TO EACH PAX AS THEY LEFT THE ACFT.

Data retrieved from NASA's ASRS site as of January 2009 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.