Corrosion ruled out in aircraft hole

DALLAS, July 17 (UPI) -- The National Transportation Safety Board says the hole torn in the top of a Southwest Airlines jet doesn't appear to be the result of pre-existing corrosion.

In its first report on the incident that occurred during a flight to Baltimore, the transportation safety board said there were no signs of "significant corrosion" on the Boeing 737, The Dallas Morning News reported Friday.

The NTSB said it also found no obvious, pre-existing mechanical damage.

The 15-year-old aircraft was flying from Nashville to Baltimore Sunday night when a football-size hole opened up in the top fuselage of the plane.

The jetliner landed without injury to any of the 126 passengers or crew.

Reporting on the matter Thursday, the safety board left open the possibility that some sort of metal fatigue to the aircraft's aluminum skin could have created the hole.

The next step for investigators may be to look at whether Texas-based Southwest complied with federal regulations governing the inspection of aging aircraft.