As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT SIDE BRAKE LOSE PRESSURE DURING APPLICATION WHERE YOU EITHER HAVE TO RELEASE BRAKES AND RE-APPLY OR USE CONSIDERABLE PRESSURE TO STOP. RIGHT SIDE BRAKES LOSING PRESSURE COMPLETELY DURING APPLICATION AT TAXI SPEEDS. TROUBLESHOT SYSTEM DOWN TO CO-PILOTS LT MASTER CYLINDER AND SYSTEM CHECKS GOOD. PERFORMED BLEED CHECK AND OPS CHECKS IAW CESSNA 560 MM CH 32-42-00 SYSTEM CHECKED GOOD.