What is the main purpose of bonding the aircraft and fueling unit?

Bonding the aircraft and fueling unit is essential primarily to prevent static electricity discharge during the fueling process. When fuel is transferred, especially in large volumes, it can generate static electricity due to the friction between the fuel and the surfaces it interacts with. If there is a static discharge while fuel vapors are present, it can lead to a fire or explosion. By bonding the aircraft to the fueling unit, a continuous electrical connection is established, which allows any static charge to dissipate safely to the ground, mitigating the risk of ignition.

The other options, while relevant to various aspects of fueling protocols and aircraft safety, do not capture the primary focus of bonding in the context of preventing static electricity hazards. For example, while accurate fuel dispensing and checking for fuel leaks are critical operational components, they are addressed through different procedures and equipment. Likewise, verifying the weight of the aircraft pertains to balance and loading procedures, which are unrelated to the bonding process itself.