SUMMARY OF INFORMATION FROM MANUFACTURER:MANUFACTURER HAS NOT BEENCONTACTED.RECALL AND SERVICE BULLETIN FILES WILL BE SEARCHED.ANALYSIS:THREE SCHOOL BUS BODY COMPANIES INDICATE THAT THE SUBJECTVEHICLES ARE PRONE TO VIOLENT BACKFIRING.REPORTEDLY THE PROBLEM OCCURS ASTHE CHASSIS IS DRIVEN ON THE ASSEMBLY LINE.EXPLOSIONS ARE REPORTED ASSEVERE, WITH MUFFLERS BEING BLOWN OPEN, SPEWING SHRAPNEL, FLAMES, ANDSPARKS.REPORTEDLY ONE EMPLOYEE RECEIVED SINGED HAIR AND EYEBROWS.ASECOND EMPLOYEE SUFFERED DEAFNESS IN ONE EAR EVEN THOUGH SHE WAS WEARINGAPPROPRIATE EAR PROTECTION.THE PROBLEM MAY BE RELATED TO CHANGES IN THEFUEL AND EMISSION SYSTEMS, IMPROPER USE OF THE MANUAL CHOKE, AND NUMEROUSENGINE STARTS AND SHUTDOWNS ON THE ASSEMBLY LINE.PROPOSED ACTION:TO OPEN A PRELIMINARY EVALUATION.===