As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
NORTH RIVER BRAKE BOOSTERS INSTALLED WITH STC SA2318NM. BRAKE PLUNGER HAS EXCESSIVE PLAY WHICH CAUSED FLUID TO BYPASS INTERNALLY. PILOT LOST DIRECTIONAL CONTROL OF THE AIRCRAFT ON LANDING CAUSING SUBSTANTIAL DAMAGE TO THE AIRCRAFT. THREE PREVIOUS LANDINGS THAT DAY THE BRAKE FUNCTIONED NORMALLY. SITUATION COULD BE DUPLICATED BY ALLOWING THE PLUNGER TO FALL TO THE RT SIDE AND THEN BE DEPRESSED WITH NO BRAKE ACTUATION AND NO EXTERNAL FLUID LOSS.