More than 5 percent of older Boeing Co. 737 jets that underwent urgent inspections worldwide in the past week have cracks in a structure connecting the wings to the fuselage and will have to be temporarily grounded.

Boeing officials shared the preliminary findings on 737 Next Generation models with airlines on Wednesday, said a person briefed on the call who asked not to be named because the discussions were private. A total of 493 planes were inspected and 25 had evidence of cracking, said the person.

The U.S. Federal Aviation Administration, acting after an alert from Boeing, issued an urgent directive Oct. 2 requiring the checks on planes with more than 30,000 total flights by Oct. 10. There are an estimated 165 such aircraft in the U.S., including 737-600, 737-700, 737-800 and 737-900 models, the FAA said in a statement.