Hans Conser wrote:

Turbulence Shook Plane 7 Years Ago

By JONATHAN D. SALANT, Associated Press Writer

 WASHINGTON (AP) - Safety records show the American Airlines plane that crashed in New
York was severely shaken by air turbulence seven years earlier in an episode that injured 47
people.

 One possibility safety investigators are considering is that the Airbus A300 broke apart
Monday after hitting turbulence from the plane taking off before it at Kennedy International
Airport.

An aviation consultant said the plane could have been weakened by the earlier encounter.

``I would expect that the airplane underwent inspection after the turbulence encounter to verify that it hadn't been damaged and any damage that was incurred was fixed,'' Jim McKenna said.

National Transportation Safety Board (news - web sites) investigators are reviewing records and interviewing maintenance
employees who worked on the Airbus A300, and are asking questions about the 1994 incident.

``We have that information,'' board member George Black Jr. said Wednesday. ``That would be in the airplane's maintenance
jacket. Whatever they did to it at the time, if they required any repairs, it would be there. We will be looking at that event.''

 American Airlines officials declined comment, citing the NTSB (news - web sites) inquiry.

The pilot of American Flight 587 mentioned encountering the wake of another plane, according to cockpit voice recordings.
Board Chairwoman Marion Blakey said the plane lifted off one minute and 45 seconds behind a Japan Airlines jetliner, less than the usual two minutes between takeoffs.

 In the earlier incident, 47 passengers and crew members were injured on Nov. 28, 1994, Federal Aviation Administration (news - web sites) records show. The Airbus, flying from Barbados to Puerto Rico, had just reached cruising altitude at 35,000 feet. The seat belt sign had just gone off.

Without warning, the plane hit air turbulence, sending the nose up and down. The plane landed in San Juan without any other problems, but some of the passengers required hospitalization.

Though the plane has undergone major maintenance since then - the latest in December 1999 - aviation experts say the earlier turbulence could have created some unnoticed cracks.

``Certainly the investigators need to take a look at that to see if there is any damage that went undetected,'' said Tom Ellis, a
spokesman for the Nolan Law Group, a Chicago firm that represents victims of airline accidents. ``With any maintenance, there
is always the possibility of human error. You would think it's unlikely, but it's still possible.''

Still, David Stempler, president of the Air Travelers Association, an advocacy group, said the plane would have been inspected
several times since 1994. ``The plane probably went through major overhauls since then,'' Stempler said.

 Even if a crack caused by the turbulence initially went undetected, subsequent inspections should have found any problems,
 said Dean Headley, associate professor of marketing at Wichita State University and co-author of an annual study of airline quality.

``Assuming that all of those inspections were done as they were supposed to be and signed off on, you assume they would find any damage,'' Headley said.

It is real tough to detect delimitation visually. Unless they used ultrasonic
or even the coin tap test in the structural parts  of the vertical tail they would
not find the damage. A quick way to test things like that is put an accelerometer
on the tip of the tail and hit the tail someplace else with a hammer and
record the resonant frequency. To my knowledge they are not doing that on check "C's".

Mark, what kind of structural inspections are you doing over there?

Paul Lamar


 
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