UPDATE 4-US FAA to order emergency checks of older 737s

Mon Apr 4, 2011 5:53pm EDT

* Responds to Southwest in-flight fuselage tear Friday

* Boeing preparing service bulletin for airlines

* Southwest cancels 70 more flights on Monday

* Shares pare losses, but still down 2.1 pct (Updates with FAA statement)

By Karen Jacobs and John Crawley

ATLANTA/WASHINGTON, April 4 (Reuters) - The U.S. government will order emergency checks of some older model Boeing Co (BA.N) 737s for the kind of fatigue cracks that prompted Southwest Airlines Co (LUV.N) to ground dozens of planes and cancel hundreds of flights.

The Federal Aviation Administration directive on 737-300, 400, and 500 fuselage inspections, expected on Tuesday, applies to only the most frequently flown models and will involve time-consuming and repetitive electromagnetic checks.

"This action is designed to detect cracking in a specific part of the aircraft that cannot be spotted with visual inspection," FAA Administrator Randy Babbitt said in a statement on Monday.

Boeing promised its own bulletin to airlines outlining specific inspection steps.

The FAA said most of the 80 jets needing checks in the United States are planes flown by Southwest and have accumulated high numbers of takeoffs and landings.

Overseas regulators are expected to adopt the FAA order for airlines they regulate, covering another 95 planes worldwide.

Southwest is already carrying out its own round of voluntary emergency inspections after one of its planes landed on Friday in Arizona with a hole in its fuselage.

Flight 812 was heading from Phoenix to Sacramento when a 5-foot (1.52 meter) tear opened in the fuselage 20 minutes after takeoff on Friday. [ID:nN03202402]

Southwest has struggled with fatigue cracking on its older aircraft, which safety experts and other industry insiders attribute to the aggressive way it uses those planes.

"We all know that Southwest has rapid turnarounds and short hops. It's a different type of use, so you have different types of maintenance and oversight," said Jim Hall, a former chairman of the National Transportation Safety Board.

Friday's incident was the second time in two years that a Southwest plane experienced a fuselage rupture soon after takeoff at more than 30,000 feet. Both planes landed safely.

Additionally, Southwest paid a $7.5 million FAA fine for operating 737s without required fuselage structural inspections in the 2006-2007 period.

The NTSB is investigating the latest incident and will likely take a fresh look at Southwest's maintenance practices and FAA oversight of the carrier.

"They are going to be pushed very hard on this," said one safety expert familiar with the thinking of transportation investigators.

Southwest canceled 600 flights over the weekend and another 70 on Monday as it worked to inspect planes and get them back into service. Southwest hoped to complete the checks on Tuesday.

Inspections since Friday have turned up cracks in three other planes, Southwest said.

James Higgins, an analyst with Soleil Securities, said the flight cancellations will cause some revenue loss for Southwest but he doesn't expect lasting fallout from this incident. Southwest expects to close its pending acquisition of AirTran Holdings AAI.N in the second quarter.

"I don't think there is anything systematic or persistent here," Higgins said. "This is more noteworthy for its headline generation than for its likely damage to the company."

Shares of Southwest, which only operates Boeing 737s, closed Monday down 1.7 percent at $12.46, while Boeing lost 6 cents to end at $73.95. (Reporting by John Crawley and Karen Jacobs; Editing by Gary Hill and Tim Dobbyn)