Evidence Points To Foreign Object Debris

It wasn't too long ago that ANN reported the mystery of 20 front and side windshields cracking on at least 14 planes at Denver International Airport.

Well, that February 16 mystery has been solved -- and it wasn't Mr. Mustard on the tarmac with the sledgehammer. It was, instead, FOD, "foreign object debris," the stuff (substance, debris, or article) alien to a vehicle or system that could potentially cause damage, reports the Denver Post.

FOD often causes FOD -- foreign object damage -- which can be expressed in physical or economic terms and that may or may not degrade the product's safety and/or performance characteristics. All this, according to the National Aerospace Standard 412, maintained by the National Association of FOD Prevention, Inc.

Denver-based NTSB lead investigator Jennifer Kaiser said that pilots of one plane reported taxiing through "some dirt and debris" before the cracking occurred.

Airport wind gusts reached 48 mph -- at the "high end," but not that unusual, said Kyle Fredin of the National Weather Service.

FOD cracks weren't limited to one airline; they appeared within three hours on planes from SkyWest Airlines, Frontier Airlines and Great Lakes Airlines.

"The only commonality across aircraft type, operator, location, time, and phase of flight was the wind and weather," Kaiser said.

She noted that windshield fractures developed on six planes as they were taking off, some of which aborted; on one just after landing; on two as they were taxiing to the terminal after landing; on three as they were parked at the gate; on one as it was being pushed back from the gate; and on one while it was at 19,000 feet.

The cracking, said Kaiser, occurred on the outer of the three layers of the windshields; microscopic analysis showed fine particles caused pitting that in turn caused cracking.

Investigators were unable to determine the precise nature of the debris as there were no "transfer" marks of the material onto the windshields (think CSI), Kaiser said. "We have nothing at the impact sites to say this is definitively what it is."

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FMI: www.ntsb.gov, www.flydenver.com,  www.fodnews.com/article0x.html