Narrative:

The delays and confusion between pilots and mechanics is quite honestly; very unsafe. Recent email guidance dictates for 737 pilots to not accept any aircraft for flight with a hyd indication over 100%. In the amm (aircraft maintenance manual); there is a warning that says if hyd systems are overserviced that hyd fluid will enter the pneumatic ducts and enter the cabin causing injury. Here is the discrepancy between pilot email guidance and [the maintenance task]; hydraulic reservoir servicing has the above mentioned warning about overfilling the reservoirs and also directs to fill the hyd reservoirs by the reservoir gauge; from between the ref mark and full; which is approx. 92%; to insure reservoirs are not over filled. [It further states] that 'if you must lower the hydraulic fluid level because it is too high (more than 100%); do these steps'; as in remove fluid; as per the email guidance I might add. This is very clear; directive and definitive as; I say again; per the apa guidance.now for mx argument; which I disagree with; but I believe is open for interpretation.mx on this [particular aircraft]; and the attending mechanic; would not sign off the aircraft per the above task for obvious reasons. His guidance from his managers; was to use the following task; which includes the above servicing task; thereby creating the following discrepancy:mx signed off the aircraft; incorrectly; in my honest opinion with the following task.task hydraulic fluid quantity transmitter/indicator inspection; which allows a reading of 100 (+/-9%).in my opinion; this is a roundabout way to allow an overservice situation that in my opinion has no bearing on servicing the hyd systems on an operational basis.

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Original NASA ASRS Text

Title: Boeing 737 Captain reported that the aircraft hydraulic system has been routinely overserviced.

Narrative: The delays and confusion between pilots and mechanics is quite honestly; very unsafe. Recent email guidance dictates for 737 pilots to not accept any aircraft for flight with a hyd indication over 100%. In the AMM (Aircraft Maintenance Manual); there is a warning that says if hyd systems are overserviced that hyd fluid will enter the pneumatic ducts and enter the cabin causing injury. Here is the discrepancy between pilot email guidance and [the maintenance task]; hydraulic reservoir servicing has the above mentioned WARNING about overfilling the reservoirs and also directs to fill the hyd reservoirs by the reservoir gauge; from between the ref mark and full; which is approx. 92%; to insure reservoirs are not over filled. [It further states] that 'if you must lower the hydraulic fluid level because it is too high (more than 100%); do these steps'; as in remove fluid; as per the email guidance I might add. This is very clear; directive and definitive as; I say again; per the APA guidance.Now for MX argument; which I disagree with; but I believe IS open for interpretation.MX on this [particular aircraft]; and the attending mechanic; would not sign off the aircraft per the above task for obvious reasons. His guidance from his managers; was to use the following task; which includes the above servicing task; thereby creating the following discrepancy:MX signed off the aircraft; incorrectly; in my honest opinion with the following task.Task Hydraulic fluid quantity transmitter/indicator inspection; which allows a reading of 100 (+/-9%).In my opinion; this is a roundabout way to allow an overservice situation that in my opinion has no bearing on servicing the hyd systems on an operational basis.

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.