Final answer:
In most fuel jettison systems such as on aircrafts and rockets, fuel is typically expelled overboard by pumping it out, often as a means to reduce weight in emergency situations. Safety measures are taken to prevent damage or pollution.
Step-by-step explanation:
In most fuel jettison systems, particularly in aircrafts, fuel is typically moved overboard by pumping it out. This process involves the use of a pumping system that expels unwanted fuel, which might occur due to the need to reduce the aircraft's weight in an emergency situation. Examples of these systems include the jet engines where a liquid fuel/oxidant mixture and a solid mixture are used.
Rocket propulsion also uses a similar technique, where fuel burning can lead to changes in velocity or acceleration. It's important to note though, that in all these systems, safety and environment impact considerations are vital. For instance, care must be taken to ensure the fuel is discharged in a safe direction and altitude to prevent any damage or pollution.
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