Parking Brake Valve trouble potential

[SierraYankee]

Dear Skymaster pilots and mechanics;
what are the possible troubles a malfunctioning parking brake valve (the entire unit) could cause ? This is for a P337H, SN P33700305
Could a leaking valve cause brake pressure loss in both L & R sides ?
Could a 'broken' valve cause air to entrain into hydraulic lines, or oil leaks.

Any conceptual thoughts would be of help.

Thanks in advance