Investigators: American crash is 'new day' in fieldBy BILL ADAIR, Times Staff Writer
© St. Petersburg Times
published May 4, 2002
HAMPTON, Va. -- In a NASA laboratory at the Langley Research Center, the tin kickers are learning about plastic.
On one side of the cavernous lab Friday morning, an ultrasonic probe was moving back and forth to find flaws in the broken tail fin from American Airlines Flight 587.
A few feet away, NASA engineers had reassembled the fractured pieces of the plane's big rudder. The engineers had drawn a grid on the rudder and written words such as "Disbond" to indicate areas that had been damaged when the Airbus A300 crashed in Queens, N.Y.
The examination in the NASA hangar is providing an important lesson for the crash investigators from the National Transportation Safety Board. They have long been known as tin kickers because of their skill at finding clues in broken metal.
But the Nov. 12 crash of Flight 587 revealed a weakness: They have had little experience with composites, the lightweight bonded fibers that are increasingly used on airplanes.
The NTSB has sought help from NASA engineers such as James H. Starnes, a quiet man with Buddy Holly glasses who has more than 30 years of experience with composites. He has analyzed the nose cone of the space shuttle and figured out why the fuel tank in an experimental spacecraft cracked.
Starnes said the NASA engineers know the strengths and weaknesses with composites because of years of aggressive testing.
"We've seen a lot of things fail -- because we purposely failed them," he said during a press demonstration Friday.
NTSB chairman Marion Blakey said it was important that crash investigators learn more about composites. "This is really a new day in accident investigation," she said.
The composite fin is the focus of their inquiry. Investigators are trying to determine why it snapped off the plane shortly after takeoff from John F. Kennedy International Airport. The plane then plowed into a neighborhood, killing all 260 people on the plane and five on the ground.
They are considering two main theories. Either it snapped off because alternating rudder movements put unusually strong air loads on the fin; or it broke because of a pre-existing flaw in the composite material.
Composite materials such as carbon fiber reinforced plastic used in the fin are being used in a growing number of planes because the materials are strong and lightweight and can be tailored very precisely to withstand the unique forces in different parts of the plane.
The scene in the NASA lab shows how crash investigation is changing. Instead of the usual shards of metal, the broken pieces had edges that looked like torn fabric. The tears revealed thousands of individual fibers that, when bound with epoxy, make composites so strong.
Starnes said it took two months to create an ultrasonic map of the fin.
Only recently have investigators begun more aggressive tests on the 28-foot-high panel. Pieces have been removed so they can be subjected to forces to simulate what might have happened to Flight 587.
Starnes talks about the composite pieces like a detective talking about a murder witness. He says the pieces must be "interrogated" to see what they reveal.
He is confident the tests will provide answers about the crash.
"I'd like to believe we'll eventually understand what happened -- or at least have a short list" of things that led to the crash.
"We'll be extremely lucky if we get down to just one."
-- Times staff writer Bill Adair can be reached at (202) 463-0575 or email@example.com.
© 2006 • All Rights Reserved • Tampa Bay Times
490 First Avenue South St. Petersburg, FL 33701 727-893-8111
From the Times wire desk
From the AP