DRIVER HEARD A NOISE FROM THE REAR OF THE BUS AND PULLED OVER AND CHECKED THE BUS. AIR RIDE BAGS WERE DEPLOYED. FOUND PROBLEM - A NUT HAD FALLEN OFF THE CONTROL ARM OF THE AIR PRESSURE VALVE, CAUSING AIR RIDE BAGS TO DEFLATE. IT WAS REPAIRED. BUS CONTINUED ON ROUTE. 15-20 SECONDS INTO ROUTE, DRIVE SHAFT FAILED AND BROKE OFF THE BUS, STRIKING A PASSING VEHICLE. IT KNOCKED A HOLE IN THE GAS TANK OF THE PASSING VEHICLE. WE WERE NOT WARNED THAT IF AIR RIDE BAGS WERE DEPLOYED, THE DRIVE LINE WOULD FAIL, WHICH COULD HAVE CAUSED DEATH TO STUDENTS ON THE BUS, PASSING MOTORISTS OR PEDESTRIANS.*AK