Originally Posted by
bobwysiwyg
As far as I know cargo holds are pressurized. How do you suppose those pets of passengers survive as well shaving cream. They may have other rationale for the request, but a lack of pressure in the hold is not one of them.
Yes, the entire airplane is pressurized to the same pressure. It has nothing to do with the cargo or baggage, and everything to do with the aircraft's structure.
The airplane is a cylindrical pressure vessel, basically a light weight air tank. If there were a difference in pressure above and below the cabin floor, it wold buckle. Plus it would require that the floor is hermetically sealed o keep cabin pressure from venting down into the hold. So, think, one big air tank, that happens to have a floor stretching across the middle.
BTW - the above was proven in a a very unfortunate event when a cargo door failed, causing the cabin pressure to buckle the floor, leading to a crash.
As to hydraulic lines. If their bled properly there's no air inside to expand and push fluid out. Plus the total volume of fluid is too small to be of concern anyway, so don't sweat this bit of nonsense, and don't go out of your way to tell anyone you have hydraulics on the bike.