As Boeing’s T-7 chief test pilot continues logging flights and checking off outstanding test points for the company’s new tactical trainer jet to replace the aging T-38, the company is preparing to incorporate its engineering and manufacturing development aircraft into the demonstrations later this year.
After surpassing 400 flight tests earlier this month using the two existing prototype jets, pilot Steve Schmidt said officials are dividing the remaining testing of the aircraft between St. Louis, where Boeing’s T-7 production line is, and Edwards Air Force Base, CA, as the prototype platforms work through proving they “can operate safely in the envelope that the Air Force has asked for in their proposals.”
“As a test pilot, it’s pretty unique to start a project from inception and bring it all the way to this point,” Schmidt said last week, referencing his participation in the trainer’s first flight in December 2016. “The planes have been performing, I think, really well. We’ve done a lot of work already to expand the envelope.”
Schmidt told reporters in a Jan. 28 interview that he’s looking to finish high angle of attack testing on one of the prototypes, before transitioning to departure spin testing later in the year at Edwards AFB. On the second prototype aircraft, he said officials are poised for cargo pod testing in St. Louis, among other things.
Schmidt said thus far, the aircraft has flown “well above” 40,000 feet, showcased crucial functions such as the mid-air engine restart and more, as the program strives to hit around five flights per week.
Once the EMD aircraft are brought in this year, the first two will undergo propulsion testing, while later aircraft will demonstrate “a lot of mission system testing as far as just basic flying aircraft, navigation, flight approaches” as well as the embedded training component, Schmidt said.
That mission systems work will be tied to the third of five EMD jets, Schmidt noted, while the fourth and fifth aircraft are part of the embedded training piece, “where we link these aircraft together and prove that you can do” the virtual tactical training work the Air Force is seeking.
“The jet right now is undergoing all its subsystem tests in the hangar,” he said. “Everything’s been installed and now we’re just doing the functional checkout, and then following that, obviously, we’ll do a bunch of engine runs and then some taxi tests and we’ll be ready for first flight.”
Program officials previously identified a wing rock issue in testing, an occurrence that generally affects aircraft with swept wings flying at a high angle of attack. In those instances, the jet's wings may stall and cause it to roll to one side. When the stalling subsides on one side, the other wing stalls, which creates a rocking motion.
Boeing spokesman Randy Jackson said the problem was solved and verified in flight in August, after officials modified “the Operational Flight Program (OFP) containing the flight control laws to correct it,” a solution that he said didn’t require further engineering work.
Schmidt, who experienced the wing rock issue firsthand, said he considered it “kind of mild,” with a “very gentle” back-and-forth motion.
“It didn’t affect our ability to complete the test points we were trying to do at the time,” he added. “It’s something we brought back and talked about in the debrief and had the engineers go off and take a look at. And then we tried to characterize it more, [say] ‘OK, what flight conditions are we seeing this at? What’s happening?’ We had a couple dedicated flights to go out and really try to investigate it so we could try to bound the problem and what was really going on.”
Both Jackson and Schmidt credited the Air Force’s and Boeing’s leveraging of digital engineering processes amid flight testing, a combination they said allowed the program to identify and address issues ahead of time.
“Early discovery is key, and that’s why we push hard on flying our [prototype] aircraft before we get the EMD to try to flush out any kind of potential issues and get an early start on resolving anything,” Schmidt said, adding: “It’s the nature of flight test. We go out, really we’re looking for problems. We want to find it in flight test before we release it operationally and put a student in there.”
Boeing is anticipating a milestone C decision will come in July 2023, followed by initial operational capability in fiscal year 2024, Boeing's T-7 program manager Paul Niewald told reporters during a December visit to the trainer’s production line in St. Louis.