As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED. DURING NORMAL BRAKING THE BRAKE PRESSURE GAUGE DROPS BY 100 PSI AND DURING APPLICATION B HYD SYSTEM DROPS 10 PSI. TIGHTENED B NUT AT HYDRAULIC ACCUMULATOR ISOLATION VALVE, PER 20-50-11. LEAK CHECKED GOOD, PER AMM 29-00-00. ACCOMPLISHED BRAKE BLEED, PER AMM 32-41-0.