AD Follows 2009 Incident In Which A Football-Sized Hole Opened In The Roof Of A Southwest Airplane

The FAA will publish an airworthiness directive in the Federal Register Wednesday ordering the inspection of 109 Boeing 737-300, -400, and -500 airplanes. Most of the planes covered by the AD are reported to belong to Southwest Airlines.

The move follows a 2009 incident in which a football-sized hole opened up in the roof of a Southwest 737-300 during a flight. In a statement issued on Monday, the FAA says that it "always evaluates the effectiveness of our safety improvements" and that the AD is intended "to reduce risk further and assure continued safe operation."

The inspections are expected to cost operators of the airliners about $5.2 million, according to a report appearing in USA Today. If repairs are needed the cost is estimated to be nearly $18,000 per airplane.

This will be the third AD to be issued in relation to the incident, which occurred on a Southwest flight from Nashville to Baltimore. The plane diverted to Charleston, WV, and made an emergency landing. There is at least one additional AD in development associated with that flight.

The FAA said the AD to be published Wednesday was due to reports of more cracks found in joints around the crowns of 737 fuselages caused by repeated pressurization cycles.

(Southwest 737-300 pictured in file photo. Not incident airplane)

FMI: www.faa.gov