Date: 201502
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Light: Night
Aircraft: A320
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Parked
ATC / advisory: Ramp ZZZ
Aircraft component: Hydraulic Syst Pressure/Temp Indication
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Flying
Reporter qualification: Flight Crew Commercial
Human factors: Training / Qualification; Time Pressure; Confusion; Communication Breakdown
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural MEL / CDL
Detector: Person Flight Crew
When detected: Pre-flight
Result: General Maintenance Action
Contributing factors: Aircraft; Human Factors; MEL; Manuals
Primary problem: Manuals

Narrative: During preflight; the first officer noticed on the HYD ECAM page that the line extending up from the blue pump was green instead of amber as it should be with no Blue System pressure. The System was otherwise indicating no pressure. We entered the discrepancy in the log book and called maintenance. The maintenance technicians were instructed by Maintenance Control to apply MEL 29-30-03F; ECAM HYD Page Indications; System Pressure.  I was uncomfortable with the validity of this MEL as our Flight manual indicates that system pressure is depicted by the three numerical values at the top of the ECAM page only. I brought this up to the maintenance technicians who were applying the MEL and they said they were doing what Maintenance Control had instructed them to do and assured me that that green line was; indeed; a pressure indication. I objected and asked them to provide some form of documentation to show that this fell under the MEL they were applying. Maintenance Control was not willing to provide any documentation; but the technicians provided some documentation that this was a pressure indication.... Still not comfortable; I tried to call scheduling to get a number to talk to a chief pilot but sat on hold for quite some time. I also tried to look up some reference which would give me an idea of whether this MEL was appropriate. As we no longer have any kind of a Systems book other than the A320 training manual; which is too vague for this purpose; I was unsuccessful in that endeavor. At this point; I had nothing other than a vague recollection from my original systems training in 1996 that this was different from a system pressure; and the people whose job and responsibility it is to determine what is an appropriate MEL all assured me that it was correct. At this point we looked again at the ECAM HYD page and noticed the line had turned amber (normal). At that point; since the problem was clearly documented the fault no longer existed and we couldn't find anything excluding this fault from the MEL; we decided to depart.After we departed; I was still uncomfortable; so I looked again at the MEL for more definitive information. The one thing that I noticed is that for this MEL; it states that there are three installed and one may be inoperative. Because there are three numerical pressure indications at the top of the ECAM page; I feel this casts some doubt on the appropriateness of this MEL for this particular failure.The main reason the event occurred is that the MEL and Flight manuals are not specific enough; in my humble opinion to determine if this is an appropriate MEL for the system failure being addressed. Also; I have been told things by local maintenance in the past that turned out to be not correct. I can't name a case where Maintenance Control was incorrect; but after a few experiences; I don't trust maintenance to tell me what I can and cannot fly with without clear documentation. In order to be more sure of our actions; and not delay flights with maintenance issues; we need someone we can easily and quickly contact during all operating hours; whom we trust; to discuss such issues. This is a complicated airplane and history has shown me that maintenance is not that someone.  When writing an MEL; it must be impossible to think of all the scenarios which may occur like this. That is; cases where it is unclear if an MEL is appropriate. It would be helpful in this case if a note were added to the MEL including or excluding the green line in question. It would also be helpful if the Flight manual labeled this green line. I was unable to find a reference anywhere describing exactly what it is....Please understand; that like most pilots at this airline; I want to operate a safe aircraft and I want to operate on time. I find ambiguity in the operation to be my large impediment to attaining this goal.




Synopsis: A Captain reports their A320 MEL and Flight Manuals are not specific enough to determine if an MEL 29-30-03F of an ECAM Hydraulics Page Indications; System Pressure is appropriate for the system failure being addressed. First Officer (FO) had noticed on the ECAM HYD Page that a line extending up from the blue pump was green instead of amber as it should be with no Blue System pressure.