Lyon indicated that issues related to oxygen deprivation reported by F-22 pilots in the past have been essentially resolved although the investigation was continuing.
"We are certain the F-22 cockpit and surrounding workspace is a safe, effective place to operate," Lyon told the House Armed Services Committee's tactical air and land forces panel. "Continuous process improvements will ensure the safety of the F-22 workforce now and in the future."
The nation's latest air superiority fighter came under intense scrutiny after a November 2010 fatal crash was blamed on hypoxia-like symptoms suffered by the pilot. Additional pilots also reported similar conditions and the fleet was stood down and has been operated under restrictions since that time.
Lyon said the Air Force continues to transition the F-22 fleet back to normal flight operations.
"No F-22 pilot has experienced an unexplained physiological incident in flight since March 8, a span covering some 10,000 sorties and more than 13,000 cockpit hours," he testified. "This is the longest period without one such incident in years."
The general said a return of normal flight operations will be determined by successful testing and fielding of a modified combat edge upper pressure garment valve and the installation of a automatic backup oxygen system in the jet.
Fielding of the new valve is expected by year's end with the first backup oxygen system to be installed in January.
"The Air Force is committed to implementing these changes to return the F-22 to normal operations," Lyon stressed.