A Boeing Co. official said its safety experts are concerned and surprised by Friday's in-flight fuselage rupture on a Southwest Airlines Co. jet, because the company didn't project potential cracking of aluminum skins "until much, much later" in the life of such aging aircraft.

Paul Richter, a senior Boeing engineer, said at a news conference Tuesday that airlines around the world eventually will have to inspect two, 50-foot long rows of rivets and skin panels on a total of 570 older Boeing 737 aircraft. The inspections, recommended...