Pretty sure the process would go something like this:
1. Draft you rule proposal and submit to the US Class Association.
2. The US Class would consider whether to pass the proposed amendment on to the world council.
3. The US Class President would submit the proposed amendment to the world council in advance of a world council meeting.
4. The world council would consider the proposal and potentially pass it to the technical committee for consideration.
5. If the world council feels the proposal is worth adopting, it will be passed to ISAF for approval because the F18 is an ISAF international class
6. If ISAF approves the rule change it will go to the F18 world council for final ratification.
7. Amendments are also placed on one year's notice before before adopted

Someone might correct this process, but that is what I get from the International Class rules and being at the World Council meeting in Long Beach.