As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BRAKES FEEL SOFT. THEY SEEM TO WORK FINE BUT PEDALS HAVE TO BE PRESSED ALMOST ALL THE WAY. FOUND FLUID LEVELS IN ALL 4 MASTER CYLINDERS TO BE LOW. SERVICED ALL FOUR MASTER CYLINDERS. CHECKED MUTING OF ALL BRAKE LINES AND ACCUMULATOR PRESSURES. OP CHECKED BRAKE SYSTEM WITH MULE AND TAXI TESTS SHOWS NORMAL SYSTEM OPERATIONS. ALL WORK PERFORMED IAW HAWKER 800XP MM CHP 32-40.