Which regulations outline the requirements for fuel jettisoning when maximum takeoff weight exceeds maximum landing weight?

The correct choice addresses the specific regulations that govern the operations of aircraft, especially concerning safety and performance criteria in the context of fuel management. Federal Aviation Regulation Parts 23 and 25 specifically pertain to normal and transport category aircraft, respectively. These parts include essential requirements for the design and operation of aircraft, including factors that relate to fuel weight and jettisoning procedures.

When dealing with a situation where the maximum takeoff weight exceeds the maximum landing weight, it becomes crucial for pilots and operators to adhere to the guidelines set forth in these regulations. They provide comprehensive protocols and safety measures that must be followed to ensure that aircraft can safely return to an acceptable landing weight without endangering their structure or performance.

Part 40 and Part 91, while important in their own right, do not cover fuel jettisoning or similar weight management practices in the context specified. Part 21 mainly discusses certification of products and parts, which does not directly address operational maneuvers required in flight. Therefore, the most relevant regulations for the scenario presented are indeed those encapsulated in Parts 23 and 25, making the selected answer correct.