DENVER (AP) — Federal safety officials are moving to let United Airlines resume using about 50 planes that have been grounded since the engine of one of them blew apart over Broomfield last year.

The Federal Aviation Administration confirmed Tuesday that it has approved Boeing’s outline of required fixes to the Boeing 777s, whose engines were made by Pratt & Whitney.

A United Airlines executive says the airline plans to start using some of the planes within a week.

They were grounded last year after a Hawaii-bound plane suffered an engine failure shortly after leaving Denver International Airport and rained broken parts over residential areas.