Boeing has said that airlines had inspected 810 of the company’s 737 NG jets around the world and found 38 structural cracks requiring repair and replacement of the affected parts.

Officials have said that the planes will be grounded until the repairs are made with nearly 5% of inspections finding cracks in a “pickle fork” – a part that attaches the plane’s fuselage, or body, to the wing structure and manages forces.

The 737 NG is the third-generation 737 and the version before the now-grounded 737 MAX, which is not affected by the issue.

Earlier this week, Southwest Airlines and Brazil’s Gol Linhas Aereas grounded a total of 13 Boeing Co 737 NG airplanes.

It’s believed that Southwest grounded two planes, while Gol said it had grounded 11. In a statement, Gol said it found “evidence of the need to replace a specific component, whose characteristics were not compliant with the standards set by the maker.”

The Brazilian airline said the fleet change would affect 3% of its passengers until 15 Dec. Gol has a fleet of 115 Boeing 737 planes, setting aside its grounded MAX planes, according to its website.

Southwest spokeswoman Brandy King said there is no timeline for when the aircraft would be back in service.

She said: “We do not have a timeline for when the airplanes will be returned to service, we are working with Boeing to schedule the upcoming repairs.”

The grounding comes after US regulators FAA ordered urgent inspections last week after the company notified the agency of structural cracks.

The FAA told the aircraft operators to inspect 165 older 737 NGs for structural cracks, but it now appears the actual number of planes covered is more than 200.

American, as well as, United Airlines said publicly earlier this week that they have not seen any cracks on its airplanes.

The FAA told CNN in a statement: “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.”

In a response to this Boeing stated to CNN that “no in-service issues have been reported.