Refueling Procedures


Drain a sample from each fuel sump and check it for debris, proper color, and the presence of any water.

Check fuel cap seals as you confirm that the aircraft has been fueled. Bad seals will let water seep into the tanks.

Fuel vapors can be very flammable. It's a good idea to supervise the refueling process, but you should do so from a safe distance away.

Be well grounded in proper fueling practices

By Dale Smith

Hang around any airport on a weekend and you'll see it time and again: A pilot pulls up, jumps out of the airplane and, after a cursory wave to the line person, disappears into the FBO in search of the bathroom and/or snack machine. After paying the fuel bill, he gives the fuel tanks a quick look—believe it or not, some pilots skip this step—fires up, and is on his way.

Unfortunately, all too often some sort of fuel-related accident happens and we all shake our heads.

Can't happen to you, you say? According to statistics provided by the AOPA Air Safety Foundation, the fuel-related accident bug bites an average of one pilot a week. Some accidents are caused by system failure. But too many of the accidents are traceable to someone's making a mistake with the fueling or servicing of the airplane. Maybe the pilot didn't get all the fuel she wanted. Maybe the wrong type of fuel was pumped into the tank. Maybe the fuel filler cap was put on incorrectly afterwards and fuel siphoned out of the tank.

Fortunately, pilots can avoid most of these problems by taking a little more care and paying attention.

Fueling basics

"The very first rule is that pilots should always stay with their airplane anytime anyone is servicing it," said Amy Koranda, manager of education and training for the National Air Transportation Association (NATA), a trade organization that represents many aviation-fuel retailers. "You need to be watching to see exactly what the lineperson is and isn't doing right."

One way to start is to make a mental note of what your fuel gauges read when you shut down. Estimate how many gallons the tanks will hold, and compare that with the actual numbers on the fuel receipt. Knowing how much fuel your airplane holds and how much it uses each hour is the best defense against running out of fuel before you run out of flight.

When ordering fuel, Koranda strongly advises that verbal instructions won't cut it. "Always fill out a service order form, and not only specify how much fuel and/or oil you need, but the exact type and grade. Then carefully compare that with your final receipt," she said.

"Oil is a big issue," Koranda continued. "The pilot really needs to be on top of what type of oil they put in. And don't forget to check that the dipstick is on tight. It seems automatic but pilots do forget." And line people do get distracted on a busy ramp. They could easily forget to put a dipstick back in or tighten it down. Make sure the lineperson didn't spill any oil on the engine. It doesn't take much spilled in the wrong place to fill your cabin with smoke and some nasty fumes.

Koranda suggests that pilots supervise each step of the fueling process. There are a couple of benefits to being there while the lineperson fills the tanks. The biggest is the tanks will get filled. That is not as simple as you may think, especially if your airplane has aftermarket auxiliary tanks. The lineperson isn't going to be looking for those, so you'd better be there to notify him.

A conscientious lineperson may ask that you step back as you watch the fueling process. Even though he or she will have grounded your aircraft, there's still a possibility that volatile fuel vapors could ignite. Some may suggest that you stand near the fuel truck, which could help to shield you.

"Don't be afraid to follow the lineperson and visually check the tanks yourself after they finish each wing," she said. "A professional lineperson won't be offended if you do. It's your responsibility." Along with confirming the fuel quantity, it's also a great time to take a look at the condition of your fuel cap seals. Worn, ill-fitting seals or incorrectly closed fuel caps can easily allow fuel to siphon out of the tank in flight. When the line crew is watching, the line crew is more likely to exercise care with the airplane itself. Scratched paint, "hose rash," and dropped fuel caps are a lot less likely to happen if you're standing there. Plan your personal pit stop for after the fueling and servicing to leave more time between when the airplane is fueled and when you sump the tanks. Aviation fuel suppliers recommend waiting at least 15 minutes between filling and sumping.

The self-serve alternative

As smaller FBOs get out of the fueling business, more pilots are faced with self-serve fueling. And while it's almost as simple as filling the family SUV, there are a couple of precautions to keep in mind. Step number one is to always ground the aircraft before you remove the fuel cap.

In fact, before you even think about fueling your aircraft yourself, learn the right way to ground it. Fuel passing through the hose builds up static electricity. Ungrounded, the resulting discharge can quickly ruin your day. Connect the grounding wire to unpainted metal on the aircraft; if it's not brittle the engine exhaust is often a good choice, otherwise try the metal lugs on the nosewheel strut where the towbar attaches. Just as important, don't forget to disconnect the grounding line before you try to taxi away.

Should you find yourself needing to fuel from containers, always use metal cans, because they can be grounded. Never use a plastic container to fuel an aircraft.

Contamination from dirt and debris is the next biggest danger associated with self-fueling. Take a second to look at the fuel nozzle itself. If pilots drag the nozzle across the ground it picks up dirt, so it's a good idea to carry a rag in your pocket to wipe the nozzle off before you insert it into the tank.

Professional line service people also recommend that you take a moment to look for sharp edges on the nozzle. If there is a sharp edge and you aren't careful when you insert it, you could easily damage the tank. This is critical for aircraft with bladder tanks. While most have pads at the bottom, you can still cut though it if you aren't careful. To be safe, never insert a nozzle more than three inches into the tank.

Don't skip the preflight

The tanks are full, and you're ready to go. Right? Wrong. A detailed preflight is still necessary. But why, you ask? Well, just because he put fuel in the airplane don't assume that it's the right kind of fuel.

More than one misfueling accident has had its beginnings in the wrong fuel—or contaminated fuel—being added to the refueling truck at the fuel farm. As the pilot in command, you are solely responsible for making sure that the fuel in the tanks is the correct fuel for that airplane. A quarter-mile off the departure end of the runway is no time to discover a problem.

The first line of defense is at hand when you visually inspect the fuel quantity in each tank. Take an extra second or two and smell the fuel in the tank. You should know what avgas smells like. If it doesn't smell right, it's not. Next, check for the proper color of the avgas when you take samples. Know your engine and know what type of fuel it needs. Remember, you should specify the fuel when you fill out your fuel order form.

And in case you've forgotten, each grade is dyed a special color for easy identification. The most widely used grade, 100LL, is blue. Some FBOs still offer 80/87 fuel, which is red. Green was the color of 100/130 fuel, which is no longer produced.

If any two grades get mixed in your tank, the fuel will be clear—which may make you think there's lots of water in the tank. If you get a jar full of clear liquid that smells strongly of avgas, check with your FBO's maintenance technician before takeoff. Do the same thing if your fuel smells like kerosene; it may have been contaminated with jet fuel.

And there's one more very important point we have to discuss—how to properly dispose of your fuel samples. Almost since the beginning of aviation pilots have poured fuel samples onto the ground. No more. The Environmental Protection Agency is cracking down on this habit all over the country. A Florida school recently got socked with a fine of nearly $25,000 for improper "sump dumping." So what do you do? Only a clean fuel sample should be returned to the aircraft tanks. There are a couple of specially designed sample jars on the market that filter out any impurities and allow you to safely pour the good fuel back in the tank (see "Pilot Products," May AOPA Flight Training). And most FBOs now have sample collection drums located near their fuel trucks or self-fueling pumps. It's a little extra work, but it could save you from paying a big fine to the EPA.

Fuel for thought

We've covered a lot of ground, but there is still plenty to go. The best way to learn how the professionals do it is to ask your FBO's supervisor of line service to give you a lesson in the right way to fuel an airplane. Chances are, if they've received any structured training themselves, they'll be happy to show the right way.

Another excellent source of information about your aircraft's fuel and fuel system is the AOPA Air Safety Foundation's Fuel Awareness Safety Advisor. Finally, NATA offers its Safety First Program, a professional line service training course. If your FBO doesn't currently use it, as a consumer you have a right to suggest it.

A well-informed and knowledgeable pilot is best able to fulfill his or her responsibility to fly safely. That duty begins on the ground, before the preflight, when the aircraft is refueled.

Dale Smith is an aviation journalist living in Jacksonville, Florida. A private pilot, he has been flying since 1975.

Photography by Mike Collins