United Airlines (UA, Chicago O'Hare) has grounded twenty-five B777-200s and B777-200(ER)s in order to perform overdue wing leading edge inspections that were missed for reasons currently under investigation, the Wall Street Journal has reported.

The carrier self-reported the issue to the Federal Aviation Administration (FAA). While some flights were cancelled on September 19-20 due to a lack of aircraft, United said the grounding would not result in any additional cancellations going forward. The necessary maintenance checks on all aircraft will take around two weeks, with each individual inspection being carried out overnight. The carrier and the regulator are investigating why the scheduled inspections were missed in the first place.

The ch-aviation fleets advanced module shows that United Airlines' fleet of B777-200s comprises nineteen -200s and fifty-five -200(ER)s. All of the -200s and a substantial part of the -200(ER)s were grounded until recently due to safety concerns related to their Pratt & Whitney PW4000G engines. The current missed inspections do not pertain to the engines.