Some of the biggest lifesavers to the pilots flying C-17 Globemaster IIIs out of Joint Base Lewis-McChord McChord Field drive trucks nicknamed "Big Green" and spend their days discussing chemical terms like freeze and flash points of various liquids.

These aren't chemists, but Airmen-fuelers from the 627th Fuels Management Flight, part of the 627th Logistics Readiness Squadron. Made up of less than 70 people, the flight provides and distributes all fuels on McChord. That's a big job, with more than 36 million gallons of fuel being pumped into 6,000 aircraft each year, said Flight Superintendent Senior Master Sgt. James Weber.

Under the McChord Field surface is a network of oil pipes zig-zagging across the base that moves all that fuel to the flightline. But where does the fuel come from? The base gets its fuel from the private oil supplier McChord Pipeline Company. Originating at the Port of Tacoma from the U.S. Oil and Refining Company refinery, the jet fuel moves along a single 6-inch diameter, 14.25-milelong pipeline to the base.

Once the fuel arrives at the base, it flows into giant 3-million gallon bulk storage tanks. The unit operates smoothly and efficiently because of its five Defense Logistics Agency contractors who oversee the base's fuel storage tanks and turn on and off the main fuel valve each day, Weber said. There is little division in the 627th between the military and contractors, division sometimes found in other fuel units in the the Air Force, he said. Having that working relationship ensures that if fuel problems arise, DLA contractors (DLA technically owns the fuel) are going to be part of the solution to getting it fixed.

"Most people come here saying that you guys are a lot farther ahead than other bases," Weber said. "We're part of them, they're part of us, we're all together." When fuel reaches the tanks and starts its journey to the skin of the aircraft, fuel samples are taken for the presence of contaminants. Dirty fuel can be dangerous for C-17 crews, a fact not lost on the Airmen who work in the fuels laboratory. "Pilots rely on us to make sure fuel is clean because dirty fuel and airplanes do not mix," said Tech Sgt. Mark Luffy, a laboratory technician.

On average, the unit conducts 1,000 fuel tests a month.

"All fuel on McChord is sampled at some point in the supply chain," Weber said. The laboratory team looks for foreign matter that could affect the fuel's ability to burn. For example, large water particles can lower the flash point below the necessary Air Force specifications, making the fuel unsafe to use. If after several tests the results keep coming back positive, lab officials have the ability to pull the fuel anywhere on base to see if other fuel samples are tainted. The likelihood of this happening is very rare, as fuel is tested multiple times before it reaches the aircraft.

"I'd rather make the call and stop a plane (because of dirty fuel) and retest it than put pilots' lives at risk," Weber said. "But I can honestly tell people that our fuel is good."

The McChord fuels laboratory does more testing than most other bases because the unit is involved in a fuels additive pilot program. Fuel Systems Icing Inhibitor is injected into the jet fuel to bring the freezing point of water above the freezing point of fuel, so that the hardened water particles will be filtered through one of the many separators installed within the pipeline and pump houses. The Jet A fuel meets the same military specifications as JP-8, and burns the exact same in flight. Weber said the Air Force plans to save nearly $40 million when the program goes Air Force-wide, which has the potential to save billions years later.

Next up on the fuel's journey is to the hydrant's Fuel System Pump House. That's where the fuel is filtered through more separators before being funneled into one of 28 hydrant pits that fuelers can pump from into the aircraft. The pump house can move up to 2,400 gallons per minute in case many aircraft are being refueled at the same time, said Jeff Doll, who works at the pump house. This is also the location where the additive is injected into the fuel. Because it's a pilot program, the company that owns the product, Doll said, is making changes to the additive levels all the time.

Finally, hydrant vehicles operated by servicemembers like Airman 1st Class William Hunter hook up heavy hoses to the hydrant storage tanks located on the flightline to pump fuel into the C-17s. This is no easy process, as safety is key throughout the fueling process. All directions must be taken by the plane's crew chief, including the discussion of how much fuel to put into the aircraft, depending on the mission. Hunter said fuel distribution is one of the most important jobs in the Air Force. "

Everything can be working fine in the airplane, but it can't get off the ground without (fuel)," Hunter said.