All school buses shall be inspected annually by the Washington state patrol. Inspection dates must be determined by the chief of the state patrol. School districts must be notified by the chief of the state patrol prior to each annual inspection of the time and place of inspection. School buses not presented for inspection at the time and place scheduled by the chief of the state patrol may obtain the appropriate inspection on or before August 31st of the current year. If the vehicle is not inspected on or before August 31st, the bus must not be operated as a school bus unless the requirement is temporarily waived in writing by the chief of the state patrol or until the school bus has passed a required inspection. A second inspection of at least twenty-five percent of each school district's fleet must be conducted annually by the Washington state patrol. This second inspection shall be unannounced and the inspection team must select which buses in the fleet it will inspect. These unannounced inspections must be scheduled so that they do not disrupt the regular transportation program.