The Air Force is giving the green light to launch at least 24 flights of the T-6 Texan II trainer aircraft next week to test new maintenance procedures after officials halted operations earlier this month for hypoxia-related issues, a top general said Wednesday.
Lt. Gen Chris Nowland, the service's deputy chief of staff for operations, says the service is making progress in dealing with a cluster of unexplained physiological events that occurred with the trainer at Columbus Air Force Base, Mississippi; Vance Air Force Base, Oklahoma; and Sheppard Air Force Base, Texas.
"We have two technical change time orders that are being executed right now that we expect to be done" by Friday, Nowland said during a House Armed Services Committee on Air Force readiness.
"Next week we expect to start flying 24 [sorties] to start flying the airplane to test our Onboard Oxygen Generation System to see if we have the appropriate repairs and get back to flying operations," the general said.
Nowland did not disclose where the 24 flights will occur, or if the flights would be spread out across at all three bases impacted by physiological events.
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"When we maintain an airplane, it's a maintenance action," Nowland told reporters after the hearing, referring to the technical maintenance change.
Before pilots take to the air, "the time change technical order allows you to go through and perform maintenance on it, so the system, the first [change] is checking the valve, the second [will] check the overall system looking for leaks, how's the system's overall performance," he said.
Once in the air, teams in place will also begin testing a backup method: Pilots will disconnect from the OBOGS, Nowland said, flying at a restricted altitude, which he did not specify.
These flights will help "determine how's the system working, and what's the ambient air," or what a pilot experiences when he or she isn't connected to the system, he said.
Pilots can breathe free flowing air in the cockpit when flying under 10,000 feet, but need to hook up to an OBOGS above that altitude. If pilots experience hypoxia -- disorientation, shortness of breath, confusion, wheezing -- at lower altitudes, it could be an indication something else is erratic in the aircraft.
The latest grounding has forced the Air Force to cancel one class of pilots going through the pipeline, backlogging 82 pilots until they can resume flight training when the next class begins, Nowland said.
"Most important, is safety of the air crews and trusting confidence of the aircrews and their families," Nowland said, echoing statements he made last week before the House Armed Services Tactical Air and Land Forces Subcommittee. Nowland's comments did not resonate well with some members of the subcommittee, notably Rep. Mike Turner, R-Ohio, who argued looking to the aircraft first is a mistake.
Citing a recent NASA report commissioned by the Navy to investigate physiological incidents in F/A-18s, Turner, the panel's chairman, said these physiological episodes "do not happen to planes, they happen to people."
While the T-6 system mimics the OBOG system made by Cobham in the F/A-18, Nowland demurred when asked if the Air Force, like the Navy, will pursue a new request for proposal to issue a new OBOGS concentrator.
"We're working with the Navy and taking lessons from the Navy [and] as we work through this decision tree, we'll take lessons from the Navy and we'll see how we move," Nowland said Wednesday.
The service on Feb. 1 ordered an indefinite operational pause for all T-6 aircraft.
There have been 22 hypoxia-related incidents in the T-6A in fiscal 2018 alone, Nowland told lawmakers in his written testimony at the separate HASC hearing last week.