AC Condensation at Gate
I'm looking into a fairly unusual issue where the concrete apron underneath parked aircraft is partially dissolving due to what appears to be fluid dripping out of aircraft. This is happening at several different terminals of the same airport, serving different carriers, and always directly underneath parked aircraft.
My first thought was this was some sort of de-scaler used in the aircraft water system, but our tests of the concrete show no cation enrichment, just leaching of calcium.
So I'm thinking that this is maybe due to water extracted from the air conditioning system or maybe APU bleed air system. The few diagrams I've found of aircraft air conditioning systems show that the extracted moisture is sprayed into the ram air system. However, I figure this wouldn't be done when the aircraft is parked on the ground.
Is there a secondary direct vent for this extracted water to the exterior of the aircraft? Where would it typically be, and what might it look like? Also, how hot would the water be?
Any help would be greatly appreciated!