Flight Crew Air Transport Pilot (ATP)
Communication Breakdown; Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew FLC complied w / Automation / Advisory; General Maintenance Action
Aircraft; Company Policy
Upon pushing back from the gate; I noticed that hydraulic system number one was slightly lower than number two so I told the First Officer that I was going to transfer some hydraulic fluid from the number 2 system to the number 1 system. Once completed; both systems were at 50% (40% is required). Considering that the fluid was above the minimum level and for fear of being scolded or getting into trouble for returning to the gate; I decided to proceed with the flight. We landed in our filed destination without incident and didn't see any noticeable change in hydraulic fluid levels. I told the Captain receiving the aircraft to watch the hydraulic system because there was something strange about it (just a feeling but nothing that I could prove or show). Both systems were at the same levels as they were when we departed but; again; I simply had an odd feeling about them. There are a few ways that I think this safety issue could have been avoided. Firstly; I have called Maintenance previously when the hydraulic levels were not balanced and they told me to just balance it. By doing so; any slow leak would not be noticed. Due to the nature of the operation and the need to continuously swap aircraft such small leaks could also go unnoticed. Additionally; I personally believe; and I'm not an engineer; that a 40% minimum level of hydraulic pressure is too low for operation (but again I'm not an engineer and don't have the necessary knowledge to determine what is a safe amount). Also; I believe that by fostering a culture where a pilot could freely express his/her feelings may have made me less apprehensive about calling Maintenance about an intuitive feeling even though the numbers were at or above the required levels.
A Q400 crew detected a hydraulic system quantity below 40% and transfered fluid to equalize both systems at 50% then learned later in the day the aircraft suffered a hydraulic system failure.