May 28, 2010 Vol. 3, Issue 5
In response to recent volcanic activity that disrupted European air travel, the House Subcommittee on Space and Aeronautics held hearings to learn about the impact of volcanic ash on aviation.
The Eyjafjallajökull volcano in Iceland erupted on April 14, 2010, canceling 100,000 flights and costing the airline industry $1.7 billion in revenue. The House Committee on Science and Technology asked for witness testimony about unsafe flying conditions caused by the latest eruptions. In a hearing on May 5, 2010, witnesses included Dr. Tony Strazisar, Senior Technical Advisor for NASA’s Aeronautics Research Mission Directorate; Dr. Jack Kaye of NASA’s Earth Science Division; Victoria Cox, Senior Vice President for the FAA’s NextGen and Operations Planning; Captain Linda M. Orlady, Executive Air Safety Vice Chair of the Air Line Pilots Association, International; and Roger Dinius, Flight Safety Director for General Electric Aviation.
In addition to the witnesses formally called for the hearing, Subcommittee Chairwoman Gabrielle Giffords (D-AZ) asked Thomas Grindle, a propulsion engineer at NASA Dryden Flight Research Center, to share the story of a NASA DC-8 that flew through an ash cloud in February 2000. Grindle recounted the incident:
“The scientists on board were the ones that alerted the flight crew that we were currently flying through the diffuse ash cloud from the Hekla volcano. The pilots noticed no onboard indications whatsoever. Engine parameters were normal, no smells in the cockpit, because it was night we looked for the Saint Elmo’s fire, no indications whatsoever. The scientists were the only ones because of their instrumentation on board to notice that we were flying through the cloud. The incident lasted for about seven minutes and the aircraft continued on to Sweden.
“Once there, they contacted us back at NASA Dryden and asked about what they should do and we recommended to do a complete visual inspection on all the leading surfaces of the airplane, the windshield the leading edges, to look at the engine fan blades, the engine cowls, anything that could have had any abrasive damage or anything.
“They performed those inspections and we found no damage whatsoever. Our recommendations from Edwards was to then replace the air conditioning filters and the engine oil on all four engines and hold samples for us once they were returned back to NASA Dryden.
“They flew for about sixty-eight hours in Sweden doing other atmospheric research missions and returned back to Dryden where we were able to do a complete engine borescope on all four engines and there we noticed some clogged cooling holes and abraded leading edges on the turbine section. We removed one of the engines, which was getting close to an overhaul maintenance requirement, and sent it to the engine manufacturer in Strother, Kansas. They tore it down and found more damage inside. We then removed the other three engines and sent them to the same manufacturer as well and upon those teardowns they found the same contaminations inside and the same damage listed in all four engines.”
In response to a follow-up question from Representative Giffords about lessons learned and the application of this knowledge, Grindle replied:
“Prior to us leaving Edwards we knew about the eruption, and so we purposely made our course as far north as possible and in fact we added another two hundred miles so our total distance from the volcano was almost 800 miles. At the altitude and the latest information we had gotten from the London Volcanic Ash Advisory Center we were well north of any kind of ash cloud whatsoever. Upon the engine teardown and the scientific data evaluation, some of the particles we flew through were less than one micron in diameter, and even at those limits we didn’t experience any engine parameter failures or any indications whatsoever, but the engine manufacturer who did the work specified that we probably would have started seeing performance degradation in some of the engines in as little as 100 flight hours because of the loss of cooling and other things and as far as I know, we were the only aircraft to fly in that area through the ash cloud and once we did realize we were in it, we updated the London Center and told them that we had experienced in that area and they were able to update their predictions in those areas as well.”
Read Grindle’s published report: Engine Damage to NASA DC-8-72 Airplane from a High-Altitude Encounter with a Diffuse Volcanic Ash Cloud.
Watch the C-Span video of the full hearing. (For Grindle’s testimony go to 59:00.)
