; and (bb) the selection of the tower for funding is based on objective criteria. . (C) Limitation on Federal share Section 47124(b)(4) of title 49, United States Code, is amended by striking subparagraph (C). (4) Benefit-to-cost calculation for program applicants Section 47124(b)(3) of title 49, United States Code, is amended by adding at the end the following: (G) Benefit-to-cost calculation Not later than 90 days after receiving an application to the Contract Tower Program, the Secretary shall calculate a benefit-to-cost ratio (as described in subsection (d)) for the applicable air traffic control tower for purposes of selecting towers for participation in the Contract Tower Program. . (b) Safety audits Section 47124(c) of title 49, United States Code, is amended— (1) by striking The Secretary and inserting the following: (1) Before date of transfer Before the date of transfer (as defined in section 90101(a)), the Secretary