Boeing Says Southwest 737 Jet Cracked Earlier Than Expected

Boeing Co. said metal-fatigue inspections must be stepped up on older 737s, the world’s most widely flown jet, after cracks developed earlier than expected on a Southwest Airlines Co. plane that split open last week.

Cracks on the so-called 737 Classic weren’t forecast to occur until “much later,” after 60,000 takeoff-and-landing cycles, Paul Richter, Boeing’s chief project engineer for older jets, said today on a conference call. The plane that ripped in an April 1 flight above Arizona had flown 39,781 cycles.