Narrative:

Engine #1 vibration indicator was showing 2.5 units of vibration; all other engine parameters were normal. No aircraft vibration was noted. We called maintenance to let them know that we had put the information in the aircraft logbook. We were holding at 11000 ft awaiting release to start the approach. Maintenance wanted us to 'troubleshoot' the problem. It appeared that it was only an indication problem and not an actual engine vibration. Line maintenance wanted us to turn off the engine hydraulic pump for engine #1 and turn the associated pack off. We did not elect to give ourselves an emergency for an indication problem; so we did not follow maintenance request. Also we were about to descend below 10000 ft. There is no procedure in the flight handbook or QRH for what they wanted us to do. The vibration indication was well within limits as stated in the QRH. We are not maintenance test pilots and this was a part 121 flight. I think there is a disconnect between maintenance and the pilots about what we can and cannot do. My biggest concern is that a junior crew might actually follow maintenance request.

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Original NASA ASRS Text

Title: A B737-400 CAPT RPTS CONCERN ABOUT MAINT REQUESTING TROUBLESHOOTING OF #1 ENG VIBRATION SYS AT START OF APCH.

Narrative: ENG #1 VIBRATION INDICATOR WAS SHOWING 2.5 UNITS OF VIBRATION; ALL OTHER ENG PARAMETERS WERE NORMAL. NO ACFT VIBRATION WAS NOTED. WE CALLED MAINT TO LET THEM KNOW THAT WE HAD PUT THE INFO IN THE ACFT LOGBOOK. WE WERE HOLDING AT 11000 FT AWAITING RELEASE TO START THE APCH. MAINT WANTED US TO 'TROUBLESHOOT' THE PROB. IT APPEARED THAT IT WAS ONLY AN INDICATION PROB AND NOT AN ACTUAL ENG VIBRATION. LINE MAINT WANTED US TO TURN OFF THE ENG HYD PUMP FOR ENG #1 AND TURN THE ASSOCIATED PACK OFF. WE DID NOT ELECT TO GIVE OURSELVES AN EMER FOR AN INDICATION PROB; SO WE DID NOT FOLLOW MAINT REQUEST. ALSO WE WERE ABOUT TO DSND BELOW 10000 FT. THERE IS NO PROC IN THE FLT HANDBOOK OR QRH FOR WHAT THEY WANTED US TO DO. THE VIBRATION INDICATION WAS WELL WITHIN LIMITS AS STATED IN THE QRH. WE ARE NOT MAINT TEST PLTS AND THIS WAS A PART 121 FLT. I THINK THERE IS A DISCONNECT BTWN MAINT AND THE PLTS ABOUT WHAT WE CAN AND CANNOT DO. MY BIGGEST CONCERN IS THAT A JUNIOR CREW MIGHT ACTUALLY FOLLOW MAINT REQUEST.

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.