Why do you need to connect an aircraft to a fuel pump by a metal wire?

Answer 1

It's due to an invisible force called static electricity, and it could ignite a potentially fatal fire if you're not careful when refueling an aircraft, vehicle or when filling a portable fuel container.

Gasoline fumes are volatile. Static electricity can create a spark that could cause a fire if it's near gas fumes.

This phenomenon is caused by the friction between two dissimilar types of matter carrying opposite electrical charges. Although these examples are harmless, the presence of static electricity at the fuel pump can, given certain unsafe practices, have tragic results.

Every time you pump gasoline, a charge of electricity builds up on the gasoline as it flows through a pipe or hose, and this charge takes several seconds to several minutes to dissipate after the gasoline has reached the fuel tank or container."

In most cases, this situation is not hazardous because the gasoline dispenser and the aircraft or vehicle are grounded, meaning there is a direct path through which the electricity can be discharged to the ground.

When this electricity is not grounded-such as when a portable fuel container is in the trunk or truck bed while being filled-static electricity can cause a spark that could ignite fuel vapors.

Connecting the aircragt and the pump with a wire that is grounded makes it easier for the electrical charge to escape.

Static electricity also can build up when gasoline is flowing into the aircraft. This contact sets up a grounding connection between the pump and the aircraft.

Dr. H

Answer 2

moving gasoline creates static electricity, merely like rubbing your ft on a carpet. If the plane isn't grounded to the pump and to the floor, a spark ought to ignite the gasoline.

Answer 3

You short circuit the two and eliminate static electric sparks that tend to set the fuel on fire.