Air Force officials officially began to test a 50-50 mixture of synthetic and JP-8 fuels in a Type 3 constant-pressure fuel hydrant system at Sheppard Air Force Base, May 18.

Fuel tankers, including five trucks with 100 percent synthetic fuel and three with the 50-50 blend, arrived at the base May 17 to unload 113,000 gallons of fuel.

The Type 3 system is a constant-pressure fuel structure that, as the name suggests, provides a constant fuel pressure through the pumps, lines, truck, aircraft and back to the pumps. This is particularly advantageous at operational locations where time is a factor. With this system, multiple aircraft can be refueled without a reduction in performance of the pumps.

In older systems, the pressure would degrade if multiple aircraft were being refueled. The purpose of the test is to determine the long-term effects of the blended fuel in a system. During testing, the hydrant system will be regularly monitored to determine whether or not any detrimental effects or other abnormalities occur over the extended period of time. Tech. Sgt. Randy Davidson, the Air Force Petroleum Agency Logistics Education Advancement Program noncommissioned officer, said he will conduct monthly tests between now and the end of the survey.

Sergeant Davidson said they have specific parameters for the fuel and that there have been no indications in previous tests that they will experience any issues during this test.

"This is a long-term durability test to see if the system can handle the 50-50 blend," he said. "We hope we get the same consistent levels." Ray Bunch, an Air Force Petroleum Agency quality assurance inspector, said Sheppard AFB was a natural fit to test the hydrants because the fuel specialists there don't interrupt the day-to-day flow of an operational base.

"The reason we picked Sheppard is this is a training system," he said. "We can keep the fuel isolated." The tests will last until about October or November. The six-month test period is too long to shut down a fuel yard, said Master Sgt. Jefferson Guillory III, the squadron's superintendent.

"No one wants to give up their Type 3 system on the active side," he said. "Here we have a closed system that's specific for training. It doesn't leave here." The process to begin this round of tests began May 13, Mr. Bunch said, when the entire system was "de-fueled" of JP-8 and cleaned in preparation for acceptance of the 50-50 blend. Sergeant Davidson said he conducted tests to make sure the system was ready to receive the new fuel product.

"Once we got our baseline and saw the levels were good, then we started off-loading from trucks," he said. Once the fuel was in the tanks, the blending process began by "spinning" the tank, or running 1,200 gallons per minute through the system.

Mr. Bunch said Air Force officials began 50-50 blend tests in 2006 at Tinker AFB, Okla. So far, officials have certified the B-52 Stratofortress, C-17 Globemaster III, B-1 Lancer and F-15 Eagle for non-combat operations. The F-15 should receive full certification soon, while the KC-135 Stratotanker and KC-10 Extender, the service's air refueling aircraft, are pending certification.

Air Force officials hope to be ready to deploy the 50-50 blend to all airframes within the next couple years, making these tests critical for the certification of Type 3 hydrants.

"Once we reach 2011 and we say the aircraft are ready to go and we're going to put it in the systems, we want to make sure there aren't any issues," Mr. Bunch said. [ANN Salutes John Ingle, 82nd Training Wing Public Affairs]

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