NHTSA Complaint #10394908 — 2007 THOMAS BUILT BUSES C2

THOMAS C2 - AMU PARK BRAKE SWITCH, 2007-2008 YEAR MODELS PROBLEM: MY OFFICE RECEIVED REPORTS FROM SCDE MAINTENANCE FACILITIES OF CONTINUED FAILURES WITH THE AIR BRAKE INTERLOCK SYSTEM AIR MANAGEMENT UNIT (AMU). THE FAILURE MODE OF CURRENT CONCERN IS WITH THE PARK BRAKE SWITCH IN THE AMU. THIS FAILURE MODE PREVENTS THE RELEASE OF THE PARK BRAKES. THE SCDE OPERATES 879 OF THESE UNITS. CONCERN: WHEN THIS TYPE OF FAILURE OCCURS, THE DRIVER CAN NO LONGER RELEASE THE PARK BRAKES. SCHOOL BUS DRIVERS ARE TRAINED TO SET THE PARK BRAKES EACH TIME THEY ARE LOADING/UNLOADING STUDENTS. IN MOST CASES THERE IS NO WARNING OR INTERMITTENT FAILURE. FAILURES OF THIS TYPE LEAVE THE BUS AND STUDENTS SITTING IN THE MIDDLE OF THE ROAD CREATING A VERY DANGEROUS SITUATION. THE BUS CAN NOT BE MOVED FROM THE ROADWAY UNTIL A TECHNICIAN IS DISPATCHED TO MANUALLY RELEASE THE PARK BRAKES AND ALLOW THE BUS TO MOVE. THE STUDENTS MUST THEN BE OFF LOADED ONTO A SPARE BUS BEFORE CONTINUING THE ROUTE. BACKGROUND: THE AMU WAS PREVIOUSLY INVOLVED IN SAFETY RECALL FL538 A-B FOR THE BRAKE LIGHT SWITCH MODULE FAILURE. WE ARE NOW EXPERIENCING PROBLEMS W/ FAILURES ON THE PARK BRAKE MODULE. WHEN THIS PROBLEM WAS BROUGHT TO MY ATTENTION, I HAD OUR STAFF PULL INSTALLATION INFORMATION FOR THE PART NUMBERS INVOLVED FROM ALL 45 MAINTENANCE FACILITIES. TO DATE OUR RECORDS INDICATE THAT WE HAVE EXPERIENCED THIS TYPE FAILURE ON 139 BUSES OR 16% OF THE 879 UNITS IN OUR FLEET. THESE UNITS ARE IDENTIFIED IN THE ATTACHED EXCEL FILE.