(CNN) The Federal Aviation Administration has ordered inspections of a Boeing 737 model after the company notified the agency of structural cracks.

Operators of certain 737 Next Generation planes will be required to make inspections, the FAA said.

"Boeing notified the agency of the matter after it discovered the cracks while conducting modifications on a heavily used aircraft. Subsequent inspections uncovered similar cracks in a small number of additional planes. The FAA will instruct operators to conduct specific inspections, make any necessary repairs and to report their findings to the agency immediately," the agency said.

The cracking was found in the plane's pickle forks, which attach the plane's body to its wing structure, CNN affiliate KOMO reported.

Pickle forks are designed to last more than 90,000 landings and takeoffs without cracking, the affiliate said , and there could be dire results if the system fails, it said.