Except as provided in this section, the Superintendent of Public Instruction shall not compute allowances upon expenditures of a district for which the average cost per bus per day for the class of district to which the district belongs exceeds 125% of the median as determined in Section 15250. If expenditures which exceed that percentage were caused by necessary replacement of the engine, or a necessary major overhaul, of one or more school buses, expenditures so caused may be allowed in addition to the aforesaid percentage.
Cal. Code Regs. Tit. 5, § 15284