United reportedly grounded more than two dozen planes this week after realizing they didn't undergo a required inspection.
According to CNBC, the impacted planes are all Boeing 777-200 airliners.
The planes are required to undergo inspections for the wing leading-edge panels.
United reportedly uncovered the missed inspections during an internal audit.
The carrier said the missed inspections resulted in 18 canceled flights on Monday night and Tuesday morning.
"We've completed inspections on 10 of those aircraft, and are working with the FAA to return others to service while inspections are ongoing over the next two weeks," United said, according to a statement obtained by Reuters.
United reportedly doesn't anticipate more cancelations due to the missed inspection.