I was thinking the same. I wonder if the ground crew flushes it with fresh water as soon as they land back at base or the ship.
It’s SOP to do a fresh water washdown of the outside of a Navy helo on a regular basis when a ship is underway. (The ship’s crew is absolutely THILLED by this use of potable water, BTW.) So, I would definitely think they would flush out the inside after a maneuver like this.