As the adage says, however, the devil is in the details. The cause of fluid purification has attracted a squadron of supporters, but they have come up against numerous obstacles, including a labyrinthine bureaucracy, mechanical glitches and financial constraints. As a result, after eight years of work, most of the aircraft in the Air Force still are not in a purification program. Still, proponents say progress is being made and that they are working to turn the idea into reality.

Contamination Costs

The Air Force, together with the Air National Guard, has more than 6,200 aircraft, fitted with hydraulic systems that control every thing from steering to landing gear. Their hydraulic fluids, the majority of which are based on polyalphaolefins, are robust and do not themselves degrade with use. According to officials with the Air Force Research Laboratory at Wright-Paterson Air Force Base outside Dayton, Ohio,hydraulic fluids that are kept clean maintain performance characteristics and can be used almost indefinitely.

Keeping them clean is no easy task, however, as hydraulic systems are subject to several types of contamination -water that seeps in during inclement weather and at sea, air that becomes entrained, and particulate matter that wears off components or enters through vents.

All three cause problems. Water in the fluid can cause it to freeze at high elevations, while particulate matter leads to premature wear of components in the hydraulic system. Entrained air affects the fluids properties and the way it functions -a proposition that can be significant with high-powered craft that are designed to perform with high levels of precision.

When you have too much air,it causes the controls to become spongy, said Carl Ed Snyder Jr., principal materials engineer for the Materials and Manufacturing Directorate of the Air Force Research Laboratory at Wright-Patterson. The lab is one of several offices promoting a purification program within the Air Force. Pilots flying helicopters after purification said they handled like sports cars instead of semis.

Contamination usually progresses over time until a component fails or the fluid is not safe to use. In either case, maintenance crews then break down the system and dispose of the fluid. On average, the Air Force disposes of 800,000 gallons of fluid per year. Because it is categorized as a hazardous material, bases in the United States pay up to $3 per gallon to have the material hauled away. In the case of overseas operations, some nations forbid having the fluid disposed of within their borders, complicating logistics by forcing the Air Force to transport the material out of country.

A Better Way

Fluid purification offers an alternative by removing the contaminants that cause the problems. Two portable purifiers have been approved by the Air Force, one manufactured by Pall Corp., the other by Malabar International. Both use fine filters to remove particulate matter, and a partial vacuum to take out volatile particles and water.

The purifiers come with hoses to circulate fluid between the hydraulic system and purifier,but officials say such a configuration does not cycle the fluid enough. So the Air Force prescribes the addition of a third element to the loop -a hydraulic test stand with a reservoir,commonly referred to as amule.

Officials say the purifiers can return contaminated hydraulic fluid to specification quality within two to four hours, depending on the level of contamination. If the practice were adopted throughout the Air Force, they claim, it would mostly eliminate new fluid procurement, which currently amounts to 900,000 gallons a year at a cost of $8.1 million.

Of course, continuing use of the fluid allows the Air Force to avoid disposal and associated costs, as well. In a presentation at the Military Aviation Fluids and Lubricants Workshop at Wright-Patterson last June, Al Herman of the 646th Aeronautical Systems Squadron estimated that a branch-wide purification program would save the Air Force $7.0 million annually in procurement and disposal costs, not counting maintenance savings stemming from reduced wear that should result from keeping the fluid cleaner.

There are a lot of clear benefits to fluid purification, said Herman, who has since retired from the squadron.

Obstacle Course

As early as the 1980s, there had been isolated attempts in the Air Force to investigate hydraulic fluid purification. The latest initiative dates to 1999, when the Pollution Prevention Branch of the Aeronautical Systems Center included hydraulic fluids in a project aimed at finding ways to recycle working fluids. The lead role was assigned to the 646th, which is also based at Wright-Patterson, while the Materials and Manufacturing Directorate assumed the technical role.

Progress has been slow for a variety of reasons. On one hand, proponents had to work with several chains of command, notably Headquarters Air Mobility Command (HQ AMC) and Headquarters Air Combat Command (HQ ACC), the two major users of Air Force aircraft. The directorate had to conduct extensive testing, too, to demonstrate the effectiveness and safety of purification.

On the other hand, proponents also had to sell the program to those responsible for maintaining and repairing Air Force aircraft. Each type of aircraft has its own system program office, located at Wright-Patterson or at depots around the country. These offices are responsible for managing the repair and maintenance procedures of their air-craft, including the approval of maintenance practices. Each aircrafts system office has to approve and issue technical order changes permitting the use of purified fluid in their respective air-frame, prior to hydraulic fluid purification being initiated in the field.

Efforts to obtain authorization dragged out, partly because of continuous turnover both in the offices being solicited and in those promoting the practice.

As with all of the armed forces, you have a lot of movement of people from one position to another, said Doug Chapman, hydraulic fluid purification project manager with the 646th Aeronautical. We have so many different offices that have had to be involved in this. A lot of time is spent educating people, and many times they come on board with the program only to get transferred, and then we have to start all over reeducating their replacements.

Machines and Money

The general hydraulic technical order was not changed to incorporate use of purified hydraulic fluids until 2004 – five years after the Research Laboratory started its campaign. The 646th says several program offices have issued their own technical orders, and that all others are considering doing so.

Although the bureaucracy of the Air Force has complicated their efforts, purification proponents refrain from criticizing it. Like all of the services, the Air Force has a large bureaucracy, said Lois Gschwender, senior materials research engineer at the Materials and Manufacturing Directorate. That creates its own resistance to change. But there is a good reason that our offices cant just make these changes on our own and that we have to go through all these testing and approvals. These are maintenance procedures for very sophisticated and expensive aircraft, and the first priority has to be not making any changes that are going to threaten the reliability of those craft and the safety of the service people flying them.

The campaign has been slowed by mechanical issues, too. The hydraulic test stands that the Air Force uses are not equipped to accommodate quick disconnects on the hoses from the purifiers. Master Sgt. Kevin Hibbs, of the 927th Air Refueling Wing at Selfridge Air Force Base, near Mount Clemens, Mich., developed a metal connection that can be attached to the mule and which accommodates a quick disconnect. The modification works like a charm, he and others say,but there is another problem: Technically,the modification violates a federal law prohibiting unauthorized modification of armed forces property. The new connection must undergo its own testing before a technical order can be issued authorizing its use, as well as the mule modification.

Officials say funding remains one of the biggest problems. Portable purifiers cost approximately $24,000 each. Purification proponents are seeking sources for some of the money,but some will have to come from budgets already allocated to major commands. Again, those bases have wide autonomy about how to spend that money, and funds are already tight because of the war.

Snowball Effect

Eight years after the initiative was undertaken, hydraulic fluid purification is only being practiced on a fraction of the Air Forces fleet. The campaign still receives quite a bit of attention. During the four-day fluids and lubricant workshop at Wright-Patterson last year, nearly half of the presentations focused on the subject. A few participants expressed skepticism that the practice will ever be adopted on a branch-wide basis, contending that funding and logistical obstacles are too big to overcome.

Others remain upbeat, however. In late December,officials cited a recent decision by the program office for the F-15 tactical fighter, located at Seymour Johnson Air Force Base near Goldsboro, N.C., to implement purification. Proponents say they are now counting on a snowball effect, whereby those who adopt the practice experience such positive results that others jump on board.

Our biggest fans on this are the pilots who experience first-hand the difference that it makes in performance of the aircraft, Snyder said. Were convinced that once we start getting success stories from the people in the field that the walls are going to start to crumble.

The decision by Seymour Johnson means facilities housing F-15s are required to begin purifying their fluids, though timing remains a question. The same steps still must be taken for other types of aircraft, too, but advocates say they are gaining interest from higher levels of command. Much work remains, but officials say they are increasingly optimistic.