Hopefully the title is self-explanatory. I am wondering how much hydraulic fluid - in mass and volume - is carried in normal operations for a jet (the bigger the aircraft in your answer the better).
FCOM for the A320 describes 3 independent hydraulic systems, with accumulation reservoirs for each at 6.5L,12.5L & 14.5L (1.7USG,3.3USG& 3.8USG) respectively, so +33.5 liters is a good bet, which translate to 26-33 kgs depending on fluid type.
Note that more fluid will be available in the system, but how much exactly you will need a mechanic to answer.
1$\begingroup$ The reservoirs are only a small fraction of the hydraulic fluid in the system. Most of it is in the hydraulics tubes and actuators. $\endgroup$– OSUZorbaMar 15, 2019 at 2:14