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Last updated on April 18, 2014 at 9:24 EDT

Structural Failure Now Suspected in NWA Jet Damage How Many Birds Fly at 18,000 Feet, Anyway?

July 9, 2008

By John Welbes, Pioneer Press, St. Paul, Minn.

Jul. 9–The initial speculation on the cause of a damaged nose cone on a Northwest Airlines 757 jetliner last weekend was a bird had made a lasting impression.

That changed Tuesday. Citing a lack of evidence of a collision, and the fact that birds don’t commonly fly 18,000 feet over Florida, investigators offered another theory.

“It appears to be an internal structural failure,” said Elizabeth Corey, a spokeswoman for the Federal Aviation Administration.

She said investigators were trying to determine why the nose cone failed from the inside.

The Boeing 757 was flying from Detroit when the pilots heard a bang at an altitude of 18,000 feet during their approach to Tampa, an FAA spokeswoman told a Florida television station.

Other reports cited a Tampa airport source on the bird theory. Eagan-based Northwest, meanwhile, simply noted that its plane landed without incident and no one was injured.

So what could have caused such a collapse in midflight?

Nothing is certain, but the union that represents FAA flight inspectors said minor work was done to that area of the 23-year-old plane about five years ago.

The nose cone houses the plane’s radar. The cone itself is made of fiberglass. Investigators likely will examine whether the cone’s composite materials had somehow delaminated, said Kori Blalock Keller, a spokeswoman for the flight inspectors’ union.

That section of the 757 was replaced, and the plane is back in service, Kristin Baur, a

Northwest Airlines spokeswoman, said Tuesday. Northwest technicians in the Twin Cities were examining the damaged section. The investigation is expected to take several weeks.

Boeing spokesman Jim Proulx said the nose cone, also called the radome, isn’t a “flight critical structure.” The plane can fly without it. The FAA has issued no airworthiness directives on that part of the 757, Proulx said.

“I don’t know of any incidents of radomes collapsing that weren’t related to some other underlying cause,” he said. That cause could be lightning, a bird, hail or faulty maintenance, Proulx said.

As word of the plane’s damage spread through the Tampa airport Sunday, the 757 became a bit of a spectacle. Several baggage handlers and a Southwest Airlines flight crew took cell-phone pictures of each other on the tarmac, standing in front of the damaged nose, said Peter Brylinke, a passenger who was waiting to board the plane for its next leg to Minneapolis-St. Paul.

But the passengers waiting for that scheduled 2 p.m. flight were only beginning what would be a long day.

Brylinke, a student returning to the Twin Cities after visiting family, said the plane “pulled into the gate pretty bashed up.” Some passengers told the gate agent they wouldn’t board the damaged aircraft.

Northwest delayed the flight until 8 p.m. for repairs. Takeoff was pushed back to 11 p.m., and then the flight was scrubbed because the flight crew had reached its work-hour limit. The plane holds about 180 people, and Brylinke said the flight was full.

Northwest put passengers up at area hotels and provided $100 travel vouchers and frequent flier miles as compensation. Brylinke caught a Northwest flight at 8 a.m. Monday. Most of the other passengers took a 9:30 a.m. flight on the repaired plane.

John Welbes can be reached at 651-228-2175.

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Copyright (c) 2008, Pioneer Press, St. Paul, Minn.

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