(a)
The department shall establish individual revolving fund subaccounts for eligible airports in the Aeronautics Account in the State Transportation Fund. Money payable under this section shall be credited to individual airport subaccounts annually, and may be accumulated for a maximum period of five years.
(b)
The department shall, subject to Section 21684, credit from the Aeronautics Account to each public entity owning and operating an airport or airports under a valid permit issued by the department for every airport which has not been designated by the Federal Aviation Administration as (1) a reliever airport, as defined in Section 503 (a) (19) of the federal Airport and Airway Improvement Act of 1982, as amended, or (2) a commercial service airport, as defined in Section 503 (a) (5) of the federal Airport and Airway Improvement Act of 1982, as amended, the sum of ten thousand dollars ($10,000) annually for each qualifying airport. These funds shall be paid to public entities upon request for expenditure on preapproved eligible projects. Eligible public entities may submit applications for the withdrawal of credited funds for expenditure on proposed projects in letter form to the department for review and approval. Projects identified shall be for airport and aviation purposes and operation and maintenance purposes. No payment made under this section is transferable, but shall be expended only upon the airport for which the payment is made, unless the department authorizes a payment to be transferred for expenditure on another airport owned or operated by the public entity. The department may establish any accounting systems it deems necessary to provide for the cumulation and expenditure of funds under this subdivision.
(c)
If, in any year, there is insufficient money in the Aeronautics Account to make the credits specified in subdivision (b), the department shall, subject to Section 21684, credit to each public entity subaccount an amount which is equal to the total amount of money in the Aeronautics Account multiplied by a percentage equivalent to the proportion which the airport or airports of the public entity for which credit is required to be made pursuant to subdivision (b) bear to the total number of airports for which credit is required to be made pursuant to subdivision (b).
(d)
No payment shall be made under this section to any public entity for any airport on which general or commercial aviation activities are substantially restricted if the airport is licensed to conduct these activities by the department. The department shall determine whether or not general or commercial aviation activities are restricted.
(e)
The department shall adopt rules and regulations and establish procedures to effect prompt payment to public entities for eligible airport projects from money credited pursuant to this section.