The US Air Force's use of biojet fuel could be delayed by at least two years if it is forced to certificate every civil platform it operates - despite being well ahead of schedule and significantly under budget on validating synthetics for military aircraft.

The USAF says its own extensive testing in both laboratory and operational environments on various systems has revealed no anomalies so far that would have any safety or performance implications. It is committed to fleet-wide use of the blend by 2016 and is now driving efforts for a generic 50% Fischer-Tropsch synthetic fuel to be given the green light by the ASTM fuel standard-setting organisation charged with evaluating the fuel for the missionised civil aircraft within its fleet.

"We still have additional validation tests we intend to complete, but at this point, our scientists and engineers feel very comfortable with the Fischer-Tropsch blend, as does industry to a great extent. This level of satisfaction is directly responsible for the decrease in our original anticipated testing requirements for each platform being evaluated," says Jeff Braun, director of the USAF alternative fuels certification office, who adds that efforts here are well ahead of its timeline and significantly under budget.

Braun says the USAF has already set its sights on the next "milestone" - evaluation of biojet fuels - and is now ready to embark on that having developed a roadmap using projected savings generated from its synthetic project. Due to resource constraints, however, it cannot "jump off" on a high value biojet effort until the Fischer-Tropsch programme is complete and savings realised.

"Our desire to accelerate the ASTM process is twofold. First, we cannot achieve fleet-wide certification until all USAF Commercial Derivative Aircraft [CDA] are certified. Since these slightly missionised aircraft fall under Federal Aviation Administration regulatory authority, we must await the ASTM Commercial Fuel Spec revision.

"Second, if forced to perform single-type certifications on each of the 20 CDAs, we are looking at an estimated additional $44 million cost - one we'd just as soon avoid. Worse, initiation of a biojet effort would be delayed by at least two years," says Braun.

He says his office is supporting ASTM, which has taken on a large and complex task with respect to evaluation/certification of these alternative fuels for public use and is recognised as working hard to complete analysis. However, it cautions against losing the momentum in addressing what has become a critical national security issue at a time of high oil prices.

"The USAF has an opportunity to provide tremendous assistance to the international community's quest to reduce dependence on oil imports by developing alternative sources of fuel supply both synthetic and bio. Unfortunately, this window of opportunity won't last forever."

Source: Flight International