As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UPON BLOCK IN AT DF THE PARKING BRAKE WAS SET THE BRAKES WERE RELEASED AND I FELT THE A\C MOVING . LOOKED UP AND QUICKLY SET THE FOOT BRAKES. ATTEMPTED TO SET THE PARKING BRAKE BUT IT WOULD NOT HOLD TESTED BRAKE IAH FIM 32-44. NORMAL OPERATION