United Airlines says it has found bolts in need of "additional tightening" during inspections of Boeing 737 MAX 9 which had been removed from service following the blowout of a doorplug on an Alaska Airlines aircraft last week.
United Airlines said it believed these to be "installation issues" relating to door plugs and these will be "remedied" before the aircraft type can return to operational use.
"Since we began preliminary inspections on Saturday, we have found instances that appear to relate to installation issues in the door plug - for example, bolts that needed additional tightening." the statement said.
The grounding of the 737 MAX 9 jets has caused United to cancel over 200 flights as of Monday and the U.S. mega-carrier expects a significant number of cancellations on Tuesday. "We have been able to operate some planned flights by switching to other aircraft types, avoiding about 30 cancellations each on Monday and Tuesday,".