And you find in CFR 187 the FAA has a formula to figure the cost of an inspector:
Appendix A to this part prescribes the methodology for computation of fees for certification services performed outside the United States.
d) In order to recover overhead costs attributable to the budget, all costs other than direct inspector transportation and subsistence, overtime, and Sunday/holiday costs, are assigned to the number of inspector positions. An hourly cost per inspector is developed by dividing the annual Flight Standards Operations Budget, excluding the items enumerated above, by the number of aviation safety inspections (OMB position series 1825) on board at the beginning of the fiscal year, to determine the annual cost of an aviation safety inspector. This annual cost of an aviation safety inspector is divided by 2,087 hours, which is the annual paid hours of a U.S. Federal Government employee. This result in the hourly government paid cost of an aviation safety inspector.
(e) To ensure that the hourly inspector cost represents a billing rate that ensures full recovery of costs, the hourly cost per inspector must be multiplied by an indirect work factor to determine the hourly inspector billing rate. This is necessary for the following reasons:
(1) Inspectors spend a significant amount of time in indirect work to support their inspection activities, much of which cannot be allocated to any one client.
(2) Not all 2,087 annual paid hours are available as work hours because training, providing technical assistance, leave, and other indirect work activities reduce the work time that may be directly billed. Consequently, the hourly cost per inspector must be adjusted upwards by an indirect work factor. The calculation of an indirect work factor is discussed in paragraph (f) of this appendix.
(f)(1) The indirect work factor is determined using the following formula:
where:
a=indirect work rate, and b=leave usage (total leave hours divided by total hours available for work.