Date: 201910
Local time of day: 1801-2400
Location: PSP.Airport, CA
Flight conditions: VMC
Light: Daylight
Aircraft: Airbus Industrie Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Parked
Airspace: Class C ZZZ
Aircraft component: Fuel Distribution System
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain
Reporter qualification: Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Human factors: Communication Breakdown
Second reporter function: Captain
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: Aircraft In Service At Gate; Pre-flight
Result: General Maintenance Action
Contributing factors: Aircraft; Logbook Entry; Procedure
Primary problem: Aircraft

Narrative: On [date] in ZZZ; I was observing the First Officer (in training) perform an exterior inspection; During the walk around he noticed a leak from the engine #2 upper AFT pylon drain port (above the engine exhaust). The previous day I had told him there should never be any leaks from there. I contacted local Maintenance who called Company Maintenance control. The leak was just a drop every few seconds and slowing at that time. There was a damp patch on the tarmac immediately beneath about a foot in diameter.  A few minutes later the leak appeared to have stopped. Maintenance Control stated the leak was within limits.I asked if we should at least observe the leak with the fuel lines pressurized as I thought it made little sense to measure a leak on an unpressurized system. Maintenance Control immediately stated it was unnecessary and that it was within limits. I stated I was surprised as I thought no leaks were allowed there; but Maintenance said that no; it was within limits. I asked the First Officer to turn the fuel pumps back on and I observed no changes. I asked the local mechanic what the exact name of the drain was. He called back Maintenance Control while I was standing next to him stating that the Captain wanted to know the name of the drain for the logbook writeup. Maintenance Control replied; 'Upper Pylon Drain'. That way I was certain Maintenance Control was not confusing it with the bottom engine drain mast.I wrote it up and it was signed off as being within limits. Since I had no concrete reasons to doubt maintenance at that time; I accepted the flight.Upon arrival in ZZZ1; the same leak was still present. I contacted local Maintenance and I was told that 'drains are meant for leaking' and that 'if Maintenance says it's within limits then it is'. Again; I had no objective reasons to doubt maintenance at that time; I didn't write it up a second time and left for the hotel. In hindsight; it's clear I should have written it up.The next evening; after arriving back home; I consulted my notes from a previous airline. Those outdated document states that no leak is allowed at that location and that troubleshooting includes verifying the absence of leak with the fuel lines under pressure and to perform a wet engine run.I contacted Standards with my concerns the morning after. I also called Maintenance Control from home stating my concerns and asking if they had performed any maintenance action on the leak while the plane overnighted in ZZZ2. I was told that 'since nobody else wrote it up; it must be good'. I answered the leak would be easy to miss as it probably only leaks under pressure and that we were lucky to catch it in ZZZ and ZZZ1 by doing a walkaround unusually quickly after shutting down the engines. Maintenance stated they would look into it. The plane flew several legs that day after my phone call before overnighting in ZZZ3; I'm not sure if it was fixed there.If it turns out current Airbus and Company Maintenance procedures are the same as before; there probably is no acceptable leak limits stated anywhere in the maintenance manuals for the pylon drains. Maintenance troubleshooting use to includes verifying the absence of leak with the fuel lines under pressure. What is the current proper procedure and was there any basis for Maintenance signed off my write up as they did?It is one of several recent interactions with line maintenance; where I feel expediency was put first ahead of safety. On several occasions over the last few months line maintenance has dismissed safety concerns I raised without addressing the issues.


Second narrative: [Report narrative contained no additional information.]


Synopsis: Captain reported non compliance with a reported leak from an Aft Pylon Drain that resulted in a maintenance action.