VEHICLE DESCRIPTION: CERTAIN SCHOOL BUSES EQUIPPED WITH SYNTEC SEATS FAIL TO CONFORM TO THE REQUIREMENTS OF FMVSS NO. 222, “SCHOOL BUS PASSENGER SEATING AND CRASH PROTECTION.” SOME SEATS (1) FAIL TO MEET THE REQUIRED FOUR INCH CLEARANCE DURING THE TEST PROCEDURE, WHILE STILL MEETING THE POST TEST CONDITION; (2) FAIL TO MEET THE REQUIRED FRONTAL PRE-LOAD WHEN TESTING UNDER CERTAIN CONDITIONS; OR (3) WHILE STILL MEETING THE REQUIRED FORCE/DEFECTION, EXPERIENCE WELD BREAKAGE.