Volcanos are just the tip of the iceberg

Published Sept. 8, 2014
By T.G. Kistler
Air Mobility Command Public Affairs

SCOTT AIR FORCE BASE, Ill. -- Air Mobility Command led a technical information exchange recently to study damage to aircraft engines caused by volcanic ash and airborne dust.

Scientists from the United States and Canada met in person and virtually with operators from AMC and Air Force Global Strike Command to share research and discuss policies and procedures for aviation encounters with ash and dust.

"Volcanic eruptions are, fortunately, fairly rare events," said Dr. Donald Erbschloe, AMC chief scientist. "We have a good idea where volcanic activity is located or concentrated, but we can't predict well in advance when those eruptions will occur, their severity or character. One thing is certain though, sufficiently intense eruptions can cause major disruptions to our operations and to overall flight safety."

While it's well known to aviators that volcanic ash can cause a turbine engine to shut down, this gathering also focused on the long-term effects on engine components.

Dr. Prakash Patnaik, National Research Council Canada principal research scientist, spoke about his research, which explains why maintainers might not discover gas turbine hot section damage until two years after an aviation ash encounter. He said that during short exposures to volcanic ash, problems may not be easy to see. However, small concentrations of sulfur and other alkaloids in the ash can start a chemical reaction on engine components at high temperatures that can lead to catastrophic metal failure after hundreds or thousands of hours of operation.

In an attempt to combat these long-term problems, Dr. Patnaik and his Canadian colleagues are researching erosion resistant coatings for gas turbine compressor blades and the usefulness of protective coatings and filters at air inlets.

"Our studies have shown where to look for damage and what to look for," said Patnaik. "Now is the time to extend our studies to identify the risk, and cross-leverage information across agencies to develop mitigation strategies and create a win-win situation."

Capt. Eric Lyall, Air Force Research Laboratory, gave a briefing on aircraft maintenance procedures. He said on-going studies will help Air Force personnel determine how the amount and length of ash exposure affects the maintenance needed.

Both Lyall and Patnaik also spoke about the costs associated with volcanic ash. Even small amounts of exposure can shorten the life of aircraft engines.

During a discussion on the effects of the 2010 eruption of the Eyjafjallajökull volcano in Iceland, Brig. Gen. Brian Robinson, 618th Air and Space Operations Center (Tanker Airlift Control Center) vice commander, noted that costs are also inflated when aircraft have to modify their flight paths to avoid volcanic ash.

Because of widespread ash over the European continent, the Tanker Airlift Control Center routed flights to Afghanistan through Spain rather than Germany. This added time, used more fuel and cost more money. When the second eruption made those secondary routes unusable, AMC was forced to fly the opposite direction and travel two-thirds of the way around the world, or twice as far, to get to the destination. While aerial refueling was not used on the Pacific route, if it had been necessary, Robinson said, it would have required three or four times the number of tanker aircraft and cost much more.

In addition to volcanic ash, scientists have also studied the effects of dust on aircraft engines.

"Our nuclear deterrence mission holds the nation's highest priority," said Dr. Christopher Yeaw, Air Force Global Strike Command chief scientist. "At events like these, we share our scientific knowledge of atmospheric contamination and the effects debris like volcanic ash, atmospheric dust or even nuclear contamination might have on our forces. Sharing that technical knowledge and operational procedures, better prepares Global Strike Command to defend the nation and ensure a safe, secure, and effective deterrent force."

Elaborating, Colonel Joel Dickinson, Deputy Commander of the 608th Air and Space Operations Center said, "Atmospheric contamination can force us to alter our strategic bombers' routes of flight, or altitudes, or affect our ability to command and control our forces. Understanding these atmospheric phenomena, and their effects on our operations, is crucial to our demonstrated ability to hold at risk any target anywhere in the world."

Dr. John Lekki, from NASA's John Glenn Research Center, spoke about the vehicle integrated propulsion research studies he conducted involving the ingestion of controlled quantities of volcanic ash into an operating engine, which will replicate the conditions of what aircraft would have been exposed to while flying through volcanic ash. He said results from the studies will reduce the cost of operations as agencies share information and cooperate to arrive at a solution faster, cheaper and better than trying to do it alone.

Lekki hopes the gathering will result in a combined enthusiasm among many agencies, which will generate interest and funding for a long-term study.

A C-141B Starlifter, C-130E Hercules and C-124C Globemaster II