[Fulltiming]

The air in both brake systems dropping at the same rate as the primary air supply is likely telling you the check valves for the two brake systems are non-functional. They are easy enough to change out with a lift or a pit. Otherwise access is tricky. Replacing the two check values should isolate the air brake systems and only the primary air supply will drop out. The other thing to check is to make sure the drain valves on the air brake tanks are tight. If the moisture was drained out of the air brake systems and the valves were not tightened (or seated if you have the pull chain release valves on the brake air tanks) then that would cause a rapid air loss but it is unusual they would be dropping at the same rate.