The Federal Aviation Administration is instructing airlines to inspect Boeing 737 NG jetliners after Boeing told the agency it had discovered evidence of cracks in a fuselage part.
"Boeing has notified the FAA and been in contact with 737 NG operators about a cracking issue discovered on a small number of airplanes undergoing modifications," the airline manufacturer said in a statement Friday.
The cracks have been found in a part called a "pickle fork," which helps attach a plane's fuselage to its wing structure, reported Seattle ABC station KOMO. The part helps manage the forces between the wings and the jet's body.
(MORE: FAA chief to test updated 737 MAX software as planes remain grounded)A retired Boeing engineer told KOMO that "it's unusual to have a crack in the pickle fork."
"It's not designed to crack that way at all," the engineer added. "Period."
The FAA said Friday it will "instruct operators to conduct specific inspections, make any necessary repairs and to report their findings to the agency immediately."
(MORE: Boeing to start paying families of Max 737 crash victims)The cracking issue does not affect any P-8 Poseidon airplanes, Boeing said, or 737 MAX model, which is currently grounded while engineers work to correct issues with the plane's automated flight control system, the airline manufacturer added.