Although pilots often overlook evaluating the quality of the fuel they pump into their aircraft, fuel quality warrants a close look.

There is an instance of pilots finding milk in their fuel tanks. No one ever determined how the milk found its way into the aircraft.

On another occasion flight line personnel sumped a below-ground fuel storage tank and found that a liquid fertilizer company had inadvertently pumped its product into the tank instead of a liquid fertilizer tank nearby. And the passengers weren’t too thrilled when a bush pilot in Alaska pumped jet fuel out of a 50-gallon drum through a dirty rag into his turboprop. He was, however, their only way home. Ignorance may be bliss but it isn’t necessarily safe.

Lucille Fisher, president of Quality Resources in Lyndhurst, Ohio, told AIN, “The Air Transport Association has ATA 103. It was written for the airlines to meet FAA requirements for fuel quality in aircraft engaged in Part 121 operations. Oddly enough, there is no standard for FBOs or corporate flight department fuel farms.”

The consensus seems to be that if nothing is happening, nothing is wrong. “Pilots think just because it’s a big flashy FBO in a large city it must be OK,” Fisher said. “Think again. A very well-known FBO chain in a major city didn’t pass an ATA 103 audit when one of its regular, high-volume customers requested it of the FBO. The results showed things that needed to be fixed.”

Fisher said pilots should be asking specific questions of their refuelers: How often do you change filters? How often do you sump your truck? Do you sump it until it’s clear and bright? “Pilots should check the fuel truck because most FBOs don’t,” she said. One pilot told me when he asked the flight line attendant when the last time was that he’d sumped the truck his response was, “What do you mean?” When the pilot located the sump valve it was rusted shut. “There are a number of products available such as Avmates that make it simple to detect water,” Fisher said.

“An even larger problem is that many FBOs will use poorly trained personnel on the flight line to do refueling. Worse, they put the junior person in charge of the fuel farm,” she said. “While the fuel companies have programs to train individuals, there’s no requirement that the purchaser must do so.”

Amy Koranda, director of safety management for the National Air Transportation Association (NATA), echoed Fisher’s concern. “You get some great line people and then you get some who are pretty clearly just passing through,” she said. “The problem is you don’t always know who you’re dealing with.”

Blowing NATA’s horn, Koranda said that if you see a flight-line attendant wearing an NATA “Safety First” patch you at least know they’ve successfully completed a comprehensive training program. “The Safety First program requires students to view 10 video modules, approximately six hours, and read a 10-chapter text. The students are also required to take a written test after each of the 10 modules and successfully complete 12 sets of practical exams given by someone authorized locally to train and qualify others.

“Even when you know you have top-notch personnel you should still monitor the refueling operation,” she said. “And be sure that your order is written down clearly before refueling starts so there’s no misunderstanding.” She added, “It’s important to understand that checking fuel isn’t as simple as just looking to see if there’s water in the bottom of a jar.”

Preventing Contamination

Any discussion of fuel comes with its own jargon. The term “bug,” for instance, refers to hydrocarbon-utilizing microorganisms. “Bug” is actually a very appropriate word as the microorganisms are miniscule creatures that live in water and eat fuel. Howard Chesneau, president of fuel quality services in Flowery Branch, Ga., put bugs in perspective. “To a microorganism a one millimeter film of water is equivalent to a six-foot-tall man standing next to the Empire State Building,” he said. “You can’t see them individually; they’re only half a micron in size.”

Chesneau said there are two types of microorganism: fungus and bacteria. “Everyone wants to call it algae but it isn’t. Algae grows on top of ponds, not in fuel.” According to Chesneau, the hazard associated with microorganisms is not just filter plugging, though that can be a serious problem. “The long-term hazard is that they produce acids that cause corrosion inside the fuel system’s components,” he explained. “And the biofilm they cause will collect on the surface of probes, such as fuel quantity and fuel temperature, and give false readings.”

Microorganisms can be controlled with additives but, Chesneau emphasized, “It is critical to understand that the use of a deicer in a fuel system, whether added by the supplier or by the FBO, does not replace the need for surveillance, dewatering or the use of a biocide.”

It is impossible to talk about fuel without some chemistry background. Two terms often heard are biocide and biostat. A biocide is a bug killer, while a biostat is an inhibitor. A biostat denies an active microorganism free water or hydrocarbons, thereby preventing it from growing, but it is possible for the microorganism to go dormant rather than die.

“Today there are only two biocides approved for use in aviation fuel systems,” Chesneau said. “They are Biobore JF and Kathon FP1.5. Either of these two additives will actually kill the bugs. The problem is that originally some deicers such as Prist used EGME, which was a biocide.”

“Unfortunately, EGME was so hazardous to humans that the EPA clamped down on its use and the manufacturers came up with Di-EGME,” Chesneau said. “What many pilots don’t understand is that while Prist is still a good deicer, Di-EGME is not a biocide; it’s a biostat. A lot of pilots think that that type of additive is still an effective biocide, but it is not.”

Chesneau said EPA registration is also commonly misunderstood. Some pilots believe that because a product has an EPA registration number it must be a biocide. “EPA approval does not mean a chemical is a biocide,” he said. “The EPA requires only that the manufacturer of a fuel treatment provide it with toxicity data concerning human health and effects on the environment. It does not require efficacy data that would show whether or not the chemical actually performs as a biocide.”

While some FBOs and flight departments might not be overly concerned about their fuel, it’s the pilot who often seems the most oblivious. Dan Nordorft, vice president of operations for Showalter Flying Service at Orlando Executive Airport, said, “A lot of people don’t even think about where fuel comes from. Pilots ask for fuel and never even crack the fuel cap open to see if we’ve filled it up. We’re happy to sump a truck if someone asks to watch, but it is very rarely that anyone even thinks of it. We maintain our quality-control records and make them available to anyone who wants to see them.”

Nordorft said it’s Showalter’s policy to do daily checks on every truck sump. “We do a clear and bright test on each storage tank and fuel truck,” he said. “On average we get a load of fuel delivered every day and we check every one. Our provider uses its tankers to haul jet fuel and avgas exclusively. Not everyone does that, and you’d be surprised what else they may be hauling–kerosene, mogas, anything. Imagine mixing some of those together.”

Nordorft said Showalter also does more comprehensive monthly checks that include inspection of the physical plant such as hoses and seals. “The general appearance of equipment is often an indicator of how well someone takes care of the fuel operation. A nasty, rusty piece of equipment reflects an attitude, and you can pretty much guess that’s the attitude when it comes to the fuel quality too,” he said.

A staffer for a Fortune 500 corporate flight department told AIN that fuel quality has long been a concern of his. “Sumping the airplane alone isn’t good enough. If they pump gallons of contaminants into your airplane, you’ve got a grounded airplane. And who can afford that? Sumping the airplane should just be insurance you haven’t gotten water through condensation or contaminants when you open up the fuel port,” he said. “We operate a Falcon 50, and if I get three thimbles full of water, that’s reasonable to expect. When you get a cup or two you have to start worrying. It’s either the supplier or, worse, you may have bad seals on the fuel caps.”

Evaluating Fuel Quality

The Fortune 500 staffer said he regularly gives his pilots training on refuelers and fuel farms. “We talk about what to look for to give them an idea of potential problems. When they’re on the road and find a supplier with a problem, we give the supplier three chances,” he said. “First we do a VAW (visual, aromatic and water) test. If the truck fails, we give them a second chance and request they use a stainless-steel or porcelain white bucket and sump the truck until no water or debris is left. Then we do another VAW test to be sure it’s not just clean water we’re seeing. If water just keeps coming out, then we give them a third chance by asking them to recirculate the entire contents of the truck so it goes through the filter. Then we run another VAW test. If, after all that, we still have a problem we just refuse the truck. Ironically, they typically just drive off and go refuel someone else’s airplane.”

Pilots should always do a VAW test before flight and after every refueling. A visual inspection of a fuel sample will show if there is sediment or other contamination in the fuel. An aromatic test (smelling it) should produce the standard smell of jet fuel.

A sulfur or rotten-egg smell strongly suggests microbial growth. A sweet smell, on the other hand, may indicate the fuel has been contaminated with avgas. Mixing avgas with jet fuel nullifies the avgas color, so it’s typically not visually discernable. While jet engines can run on such a mixture it is hard on the engine, and many OEMs have specific time limits on engine operations under such conditions. Furthermore, because jet fuel is clear or at best somewhat straw colored, it is often difficult to tell the difference between jet fuel and pure water. Use a detector kit for the water test.

“You really never know what you’re going to find,” the Fortune 500 staffer said. “We were going to supply a company with fuel and they gave us a 5,000-gallon truck to use. The first thing I did was sump the truck, and sand came out with the fuel. Turns out it had been recently sand-blasted and repainted and no one bothered to take the time to get out all the sand. I looked inside and there was sand all over the bottom of the tank. You know, the guy who made that mistake was probably having a bad day, but the pilot who doesn’t catch it is going to have one that’s a lot worse.”