October 1998Flying Smart

Aircraft Refueling

Tips for topping off your tanks

Most FBOs provide line service personnel who are happy to refuel our aircraft while we recheck the weather, run a weight and balance, or have a cup of coffee. But times are changing. Some FBOs allow customers to fuel their own aircraft, and self-serve fuel islands are becoming a common sight at airfields across the country.

Refueling an aircraft may seem simple, especially because most of us fill up our cars almost every day. Still, we should follow several important safety precautions when we refuel an aircraft.

Before fueling, be certain you know how to operate the pump. You also need to know the location of any safety equipment and how to operate it. Because mishaps can and do occur, be sure you know where the emergency fuel shutoff switch is. This switch is usually located away from the pump so you can reach it without approaching the pump itself. Also, find out the location of fire extinguishers and how to extinguish a fuel fire. (see sidebar)

It's also important for you to know a few details about the aircraft. Most important is the proper fuel grade. You should refuel aircraft with the proper grade (or higher) fuel. Never put jet fuel of any kind in the fuel tank of a piston-powered aircraft. On some aircraft that have several fuel tanks, the order in which you fill the various fuel tanks is important. Filling the tanks in an incorrect sequence can cause structural damage to the airframe or wing, and can even cause some aircraft to tip to one side!

You should take several precautions before you begin to refuel. Never refuel an airplane while a thunderstorm or lightning is in the vicinity. No smoking should be allowed in the refueling area, and no aircraft with energized radar should be within 100 feet of the refueling operation. For their own safety, keep passengers out of the aircraft while fueling is in progress.

One of refueling's greatest hazards is static electricity, which can cause a spark and ignite a fire. Use a grounding clip (bonding strap) to ground the aircraft and prevent discharge of static electricity. Attaching the clip to the exhaust stack is the most common procedure, but you can attach the strap to any bare metal part of the airframe. As a further precaution against static discharge, touch the fuel nozzle to the aircraft after the grounding clip is attached before pumping any fuel. Also, make sure the magnetos and master switch are turned off.

It's easy to damage an aircraft during fueling, so take a couple of precautions. If you use a ladder to fuel a mid-wing or high-wing aircraft, be careful not to place the ladder beneath the wing. If you pump a lot of fuel into the tanks, the landing gear strut will compress, and the wing may come to rest on the ladder and damage the wing.

Because the fuel nozzle can easily chip or scratch the paint around the fuel caps, most fueling facilities provide a guard or mat that you can place over the fueling port. Don't rest the nozzle on the lip of the tank filler port. The weight of the heavy nozzle can cause the neck of the tank to crack.

If you plan to fill the tank to capacity, be careful not to overfill. Fuel from an underground storage tank may be considerably cooler than the ambient air, and will expand as it warms in the aircraft's fuel tank. This can cause unnecessary and potentially dangerous spillage if you overfill a tank. If a spill does occur, stop fueling and get some cleanup help. Special techniques or procedures may be necessary to prevent environmental contamination. Don't resume fueling until the spill has been properly cleaned up.

Take some additional precautions if you refuel an aircraft with auto gas from a fuel can instead of directly from a pump. A fuel can should have a grounding clip similar to that on a fuel pump, and it should be grounded to the airframe before fueling. To avoid contamination, pour the fuel through a funnel with a fine mesh screen or chamois cloth. This will prevent any water or particulates from entering the aircraft's fuel tank.

Most fueling precautions are just common sense, but others may be less obvious. Be sure to get instruction about how to use the fuel pump and what precautions you need to take before you refuel an aircraft yourself.