SOUTHWEST ASIA -- The last thing a pilot probably worries about as they get ready for a mission is the quality of the jet fuel or liquid oxygen they will be using on the sortie. But for three Department of Defense civilians here, it's all they think about.
The Air Force Petroleum Agency lab here is responsible for ensuring fuels, oxygen and breathing air used in the U.S. Central Command area of responsibility meet quality standards.
"Fuel and oxygen can be considered single-point failure commodities," said David Fisher, the team leader, who is deployed from Wright Patterson Air Force Base, Ohio. "When you pump fuel directly into an aircraft, or when a pilot or firefighter puts oxygen or air directly into their lungs, you don't want anything going wrong. You're talking lives and a multi-million dollar aircraft, so you don't want to leave any stone unturned when it comes to quality of flight critical products."
The lab receives fuel samples from bases within the AOR on a regular basis so they can test for suitable aircraft use. They test a full range of fuels used by both manned- and unmanned-aircraft, as well as ground fuels such as diesel and gasoline.
"We get samples from every branch of service and occasionally coalition forces," said James La Fave, Jr., quality assurance specialist, who is deployed from Wright Patterson AFB. "It takes us about four hours to run a full set of tests on one fuel sample. The longest tests are the existent gums and the thermal stability tests which take about two and a half hours each to complete.
"The existent gums test checks to see if there are any heavy components like oil or hydraulic fluid in the fuel sample," the Helena, Mont. native said. "The test runs at 232 degrees Celsius, which will burn off the fuel, but anything like oil or hydraulic fluid will remain, leaving a gum-like residue in the test container. The thermal stability test simulates what fuel undergoes in aircraft fuel systems and when being recirculated through airframes. Besides serving as a fuel, it takes heat away from the avionics, but as fuel is exposed to friction, high temperatures and pressure, it can also potentially degrade and leave deposits."
Other fuel tests performed by the lab include viscosity, the temperatures at which fuel will begin to freeze or ignite, vapor pressure, particulate contamination, as well as sulfur and lead content levels.
Samples sent to the lab usually contain two gallons of fuel. Mr. Fisher said in order to get a sample that is representative from what might be as large as a 200,000 gallon fuel tank, a commonly used all level sampler is lowered to the bottom of the tank and then pulled back up, taking a continuous sample along the way.
In addition to normal testing, the lab is also called upon when an aircraft crash or incident occurs that requires an investigation.
"Even if we suspect an incident wasn't related to the quality of fuel, we are usually asked to run a sample because it's important to be thorough and investigate all possible contributors," Mr. Fisher said.
Much like fuel, bases throughout the AOR send samples of liquid oxygen and compressed breathing air to the lab to be tested on a regular basis.
"We are looking for specific gaseous components that we don't want aviators to breathe," said Kasie Nwaohu-Amadi, a chemist also deployed from Wright Patterson AFB. "Gases such as methane and nitrous oxide that can be normally found in oxygen need to be monitored to assure they are below health concern levels. We have limits that a supplier or storage location has to meet."
The Dayton native said the majority of samples they receive are 99.9 percent pure oxygen, though the standard DoD allowable minimum limit for oxygen purity is 99.5 percent.
The requirements for compressed breathing air are less stringent, but the lab also tests it to make sure vapors not normally found in the air didn't make their way into the tanks, like vehicle exhaust and cleaning solvents, via compressor intakes. Compressed breathing air is typically used by firefighters and people working in paint shops.
In addition to the normal testing done on oxygen, Mr. Nwaohu-Amadi's section also has a gas chromatograph. This instrument allows the lab to identify suspected contaminants in petroleum products by taking a fraction of a drop and injecting it into the instrument at high temperatures where it is instantly vaporized. The many components within the vaporized sample then separate out and can be identified.
"Being here puts our lab in the perfect location," Mr. Fisher said. "If we weren't here, it would take a tremendous amount of time to ship a sample and get everything through customs. Where it might take three or four weeks to get a sample shipped someplace else, we can get it in about a week."