WASHINGTON, July 31 (Reuters) - The Federal Aviation

Administration has failed to resolve persistent issues with

SkyWest Airlines' maintenance practices, a government

report said Thursday.

The Transportation Department Office of Inspector General

said SkyWest ( SKYW ), the largest U.S. regional airline that operates

flights for United Airlines , Delta Air Lines ( DAL ),

American Airlines ( AAL ), and Alaska Airlines, said FAA

safety inspectors have been unable to fully resolve issues

pertaining to remote return to service maintenance practices for

more than four years.