Narrative:

During the flight; we experienced a fluctuating amount of thrust on the number one engine. The N1 was oscillating plus/minus about five percent and we could feel the yaw it was causing. Other than that the engine was operating well within all other limits. We took out the engine stall/surge checklist; reduced the power; and the oscillations stopped. Later; when we put the thrust levers in similar range; the occurrence repeated itself. With the checklist complete; I called both dispatch and maintenance on the ground to tell them I was going to write up the engine. On the ground; I wrote a narrative as complete as I could with terminology stating we had experienced an 'engine surge' of about plus/ minus five percent N1. Maintenance called on the jetway phone and asked if I had turned off the pmc (power management controller) to see if that fixed the problem. I told them the QRH does not direct us to do that; and besides; we were approaching 10;000 ft and were busy with navigating and talking to ATC; so once the QRH items were done; we focused on flying the airplane; not troubleshooting on our own. Then; maintenance asked if I would mind changing the word 'surge' in the logbook writeup to another description since; apparently; the use of that term has some maintenance procedures they would rather avoid if possible. After talking to them; I agreed to change the word 'surge' to 'oscillations' and the aircraft was taken out of service to fix the engine.while maintenance was polite; they were obviously distressed that I had not tried turning the pmc's off. While this may seem like a good idea to some in 20/20 hindsight; if that's what my company wants me to do; it would help a great deal if they put that clearly on the checklist because our task load; at the time; was not conducive to anything more than flying the jet and the minor malfunction we experienced was not an emergency. Also; I would think that there is probably some sort of communication gap between maintenance and our flight manuals regarding definitions. To me; it was no big deal. The engine had an anomaly that was best described by the heading; surge/limit/stall; and that's the language I used in the writeup. Apparently; that language causes some problems with our maintenance department. Maybe this could be addressed sometime in the future.

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Original NASA ASRS Text

Title: B737-300 Captain experiences fluctuating N1 during cruise flight which disappears when thrust is reduced. In the logbook write up the anomaly is described as a surge to which Maintenance takes exception; and the reporter agrees to change to 'oscillations'. The aircraft is taken out of service.

Narrative: During the flight; we experienced a fluctuating amount of thrust on the number one engine. The N1 was oscillating plus/minus about five percent and we could feel the yaw it was causing. Other than that the engine was operating well within all other limits. We took out the Engine Stall/Surge Checklist; reduced the power; and the oscillations stopped. Later; when we put the thrust levers in similar range; the occurrence repeated itself. With the checklist complete; I called both Dispatch and Maintenance on the ground to tell them I was going to write up the engine. On the ground; I wrote a narrative as complete as I could with terminology stating we had experienced an 'engine surge' of about plus/ minus five percent N1. Maintenance called on the jetway phone and asked if I had turned off the PMC (Power Management Controller) to see if that fixed the problem. I told them the QRH does not direct us to do that; and besides; we were approaching 10;000 FT and were busy with navigating and talking to ATC; so once the QRH items were done; we focused on flying the airplane; not troubleshooting on our own. Then; Maintenance asked if I would mind changing the word 'surge' in the logbook writeup to another description since; apparently; the use of that term has some Maintenance procedures they would rather avoid if possible. After talking to them; I agreed to change the word 'surge' to 'oscillations' and the aircraft was taken out of service to fix the engine.While Maintenance was polite; they were obviously distressed that I had not tried turning the PMC's off. While this may seem like a good idea to some in 20/20 hindsight; if that's what my Company wants me to do; it would help a great deal if they put that clearly on the checklist because our task load; at the time; was not conducive to anything more than flying the jet and the minor malfunction we experienced was not an emergency. Also; I would think that there is probably some sort of communication gap between Maintenance and our flight manuals regarding definitions. To me; it was no big deal. The engine had an anomaly that was best described by the heading; Surge/Limit/Stall; and that's the language I used in the writeup. Apparently; that language causes some problems with our Maintenance Department. Maybe this could be addressed sometime in the future.

Data retrieved from NASA's ASRS site as of April 2012 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.