The parking brake valve prevents loss of accumulator pressure for fluid leaking past the antiskid valves.
Thanks, Guppy. So you're saying that leakage is normal and more a design thing rather than an aircraft age/condition issue?
I guess you could say that this is more a hypothetical situation. If the park brake valve failed to close, would the brakes still hold for a certain time period (or are these leaks monumental)?
Cheers.
NSEU