FAA issues guidance on biodiesel contaminant
The FAA’s recent special airworthiness information bulletin (SAIB: NE-09-25R1) regarding recommended safe-operating guidelines in the possible presence of the jet-fuel contaminant Fame (fatty acid methyl ester) has caused some confusion among operators. The agency is concerned that jet fuel could be exposed to Fame contamination through the use of multi-product fuel-transport systems and is taking steps to begin educating operators.
The Renewable Fuel Security Act will mandate–starting next year–a significant increase in the amount of biodiesel that petroleum manufacturers need to produce, said Mark Rumizen of the FAA’s Engine and Propeller Directorate. To accommodate that significant increase in volume, they are going to have to start shipping it through the pipelines, at which time “[Fame contamination] will be a very real concern,” he added.
Fame, the bio-component of biodiesel, can adhere to the walls of pipelines and tanks, and small traces of the contaminant can mix with jet fuel when it is transported through the same infrastructure if not properly cleaned. Small amounts of biodiesel can also remain behind in distribution manifolds, tank trucks and pipelines, resulting in cross-contamination. In Europe, which is further advanced in the use of biodiesel than the U.S., there has been one noted case of Fame-contaminated jet fuel but at a very low concentration.
At high concentrations, the contaminant can affect the thermal stability of jet fuel, which could in turn result in coke deposits in the aircraft fuel system. It could also alter the freezing point of jet fuel, resulting in fuel gelling. Both conditions can lead to engine problems including possible flameout. While the FAA has determined that the performance properties of aviation fuel containing up to 30 ppm of Fame are not affected under restricted short-term usage, current standards approved by the aviation community–aircraft and engine OEMs and petroleum producers– call for jet fuel containing less than 5 ppm of Fame. “That is the detectable limit using sophisticated gas-chromatography-type equipment, so you are talking small trace amounts,” said Rumizen. “We’re being conservative with these limits.”
According to the agency, jet operations with fuel containing more than that 5 ppm of Fame would not be in compliance with aircraft and engine operating limitations, unless OEM approved service information is issued with revised limitations. The aviation fuel industry information organization Energy Institute has established a joint- inspection project to evaluate the effects of Fame levels greater than 5 ppm in jet fuel, and is working with concentrations of 400 ppm to provide a benchmark for its analysis.
While the SAIB seemed to direct operators to take action, Rumizen cautions that it is actually meant to increase awareness of this potential situation. “The consumer depends on the fuel-distribution infrastructure to implement quality-control procedures and make sure the fuel meets the spec when it gets to the airplane, so the purpose of the SAIB is to just make sure that the operator or airplane owner mentions it to his FBO and says “Hey, are you guys aware of this?”
According to Rumizen the FAA’s regulatory over- sight begins when the fuel is loaded onto the airplane and the agency is currently involved in steps to mitigate the potential for Fame cross-contamination. “We’re working with both the engine manufacturers and airplane manufacturers as well as the oil companies to come up with a workable solution so that the airplanes remain safe and the oil companies are still able to shift the large quantities of jet fuel that are necessary to keep the airplanes flying.”
“The point here is if biodiesel is going to be a successful product long term, at some point we are going to have to figure out a way to accommodate its use on these multi-product pipelines to get it shipped around into the marketplace more efficiently and economically,” said Owen Busch, AvFuel’s vice president of supply and business, who told AIN that the SAIB has generated some good discussion among the company and its FBOs and end users.
“Biofuel is a known quantity now, so we are all managing our supply chains from a quality perspective with the operative variable that there is biofuel in the system. The awareness level is very high and there are good strong protocols in place to make sure that the aviation community is getting on-spec jet fuel,” he added.
The FAA suggests that operators become familiar with the available literature on Fame contamination listed in the SAIB and develop contingency plans and procedures with their fuel suppliers in case of a contamination situation. To provide a further level of safety, a field-level fuel-testing instrument is currently undergoing final review and will soon be available for use down through the fuel distribution chain, according to the agency.