Narrative:

The initial jet was aircraft X. Both hydraulic systems were over-serviced. We wrote it up. The first mechanic to arrive said; 'do you seriously want me to correct that? It's only over by a little bit.' I think that might have had something to do with the impending shift change; but that's not my concern. Later while maintenance was attempting to correct the hydraulic over-servicing; they discovered a leak elsewhere in the hydraulic system and the aircraft was taken out of service. This raises several questions.why are we still getting pushback about hydraulic over-servicing? The placard on the hydraulic reservoir is very clear. [A recent] pilot bulletin is also very clear. It says; 'boeing understands the impact of having hydraulic fumes in the cabin. As such; boeing has taken many steps over the years to reduce the rate of in-service occurrences. These include both guidance to maintainers to prevent/minimize over-servicing and design features to minimize the effects of over-servicing should it occur despite the maintenance guidance.'the guidance to maintainers (the placard on the reservoir that states not to over-service it) is the primary method of preventing fume events. The design features (check valves) are the secondary method of preventing fume events. Although there are no stated limits in the flight manual for maximum hydraulic quantity; why would anyone depart knowing that the primary method of preventing fume events has not been complied with and thus rely only upon the secondary method? That's certainly not the safest course of action.finally; the last question is why are we doing preflight inspections with the hydraulic pumps turned off in the interest of 'fleet commonality'? This fleet doesn't have gear doors; so it's not actually common to the other fleets. There are things we can see in the wheel well. The hydraulic pumps should be on for the preflight inspection precisely so we can look for leaks. This jet had a hydraulic leak bad enough to take it out of service. We would never have known if we had not requested maintenance servicing for an unrelated issue.

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Original NASA ASRS Text

Title: The Captain of a Boeing 737 reported that both hydraulic systems were over-serviced.

Narrative: The initial jet was Aircraft X. Both hydraulic systems were over-serviced. We wrote it up. The first mechanic to arrive said; 'Do you seriously want me to correct that? It's only over by a little bit.' I think that might have had something to do with the impending shift change; but that's not my concern. Later while maintenance was attempting to correct the hydraulic over-servicing; they discovered a leak elsewhere in the hydraulic system and the aircraft was taken out of service. This raises several questions.Why are we still getting pushback about hydraulic over-servicing? The placard on the hydraulic reservoir is very clear. [A recent] Pilot Bulletin is also very clear. It says; 'Boeing understands the impact of having hydraulic fumes in the cabin. As such; Boeing has taken many steps over the years to reduce the rate of in-service occurrences. These include both guidance to maintainers to prevent/minimize over-servicing and design features to minimize the effects of over-servicing should it occur despite the maintenance guidance.'The guidance to maintainers (the placard on the reservoir that states not to over-service it) is the primary method of preventing fume events. The design features (check valves) are the secondary method of preventing fume events. Although there are no stated limits in the Flight Manual for maximum hydraulic quantity; why would anyone depart knowing that the primary method of preventing fume events has not been complied with and thus rely only upon the secondary method? That's certainly not the safest course of action.Finally; the last question is why are we doing preflight inspections with the hydraulic pumps turned off in the interest of 'fleet commonality'? This fleet doesn't have gear doors; so it's not actually common to the other fleets. There are things we can see in the wheel well. The hydraulic pumps should be on for the preflight inspection precisely so we can look for leaks. This jet had a hydraulic leak bad enough to take it out of service. We would never have known if we had not requested maintenance servicing for an unrelated issue.

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.