Hundreds of test flight hours Boeing flew in prototype T-7A trainer aircraft cannot be used to assess the system’s operational effectiveness or suitability because the design has changed so much, the Pentagon’s top test official said recently.
Instead, the Air Force’s recently announced plans to buy extra T-7s for testing will allow the service to gather data more quickly and make up for the lost flight hours.
“Boeing flew a total of 548.5 hours in two contractor-owned and -operated prototype aircraft,” according to the recently released 2024 annual report from the office of the Director of Operational Test and Evaluation. “DOT&E will not include test data from these prototype aircraft in its final evaluation of system performance as the prototypes are substantially different from the [Engineering and Manufacturing Development] aircraft contracted.”
As it stands, there is not enough data on the T-7 yet for DOT&E to make a call on its effectiveness or suitability, the report noted.
In January, the Air Force said it will buy four aircraft to increase the T-7A test fleet from five to nine airframes. Officials said the decision will let them move faster on the flight test program and develop curriculum for the T-7A pilot training course, but they also said they were delaying the first production buy of T-7s from fiscal 2025 to 2026.
Part of Boeing’s strategy in its T-7A proposal—it received the contract for the T-X program in 2018—was that its initial design would effectively be “production representative,” and that while the production line was taking shape, testing could be largely accomplished with the prototypes, a label Boeing refused to use at the time.
By compressing the normal developmental timetable, Boeing and the Air Force hoped to reach initial operational capability by the end of 2024. Boeing was confident of this timeline because of the speed it achieved in designing and fabricating the first two T-7As using digital methods, and it bid the program under a fixed-price proposal. Saab is Boeing’s partner on the T-7.
Yet the DOT&E office noted that the T-7 has undergone—and is undergoing—design changes to address “issues including the escape system, flight control software, high angle-of-attack portion of the flight envelope, propulsion, noise and vibration, and departure resistance.”
The report noted that the the Air Force Operational Test and Evaluation Center (AFOTEC) provided perspective and feedback to Boeing throughout design and developmental testing
“AFOTEC published five periodic reports assessing progress towards operational effectiveness and suitability, with a total of 41 recommendations, 37 of which remain open,” the DOT&E report stated.
Test aircraft different from the prototypes can still be used for government-led developmental and operational testing, the DOT&E report states.
Those aircraft started arriving at Edwards Air Force Base, Calif., in November 2023, and developmental testing began soon thereafter. Boeing delivered the last of the initially planned five test airplanes to Edwards in December 2024. In the past year, those aircraft’s test flights “focused on resolving safety-of-flight issues required for airworthiness certification,” the report states.
The report is not up to date, however, having been written when only three of the five initial EMD airplanes had been delivered. By the end of September 2024, Pentagon testers stated, the Air Force had flown “46.9 hours over 46 missions in EMD aircraft, testing wing flutter, flying qualities, and radionavigation test points” with the majority of developmental testing still to go.
“These events include structural loads, subsystems, tanker formation, crew systems, On-Board Oxygen Generation System (OBOGS), mission systems, and high-angle-of-attack testing, which have the potential to drive further software and flight control changes,” the report states.
The DOT&E report noted that developmental testing would not be complete until the end of 2026, a yearlong delay from previous estimates. That estimate did not include the additional aircraft the Air Force is adding to the test fleet.
More recently, the Air Force said it hopes to reach a production decision on the T-7 by fiscal 2026, and initial operational capability by 2027.
While the program continues to suffer delays, it did meet some milestones in 2024, testers noted. That included “initial cold and hot weather testing at the McKinley Climatic Laboratory” at Eglin Air Force Base, Fla. However, the report notes that “this initial round of testing revealed several problems that require a second test event at the McKinley Laboratory” in the third quarter of fiscal 2025.
Testers also noted that Air Force student pilots “are highly likely to exceed Mach 1.0 during T-7A designated missions, particularly during the advanced fighter fundamentals course,” but the contract only requires flight to Mach .95. “The program office is … working with Boeing to contract testing in the aircraft’s transonic region prior to IOT&E,” the report says.
Testers also reiterated concerns from previous reports that the T-7A escape system “does not meet minimum safety requirements for the Air Force’s airworthiness certification and is currently operating with high-risk acceptance for airworthiness.”
While a February 2024 sled test “showed improvement at medium-speed ejections for the ejection seat sequencing,” a June 2024 test showed interference from a hose, and the “redesigned canopy fracturing system pattern did not function properly.”
The program “must successfully complete seven more sled tests before the escape system can be certified for airworthiness and IOT&E,” the report said.
The test organization is also keeping an eye on the on-board oxygen generating system. The test plan calls for 46 data points on the OBOGS collected over 10 ground and 100 hours of flight test, including high and sustained-G maneuvering. The system will soon reach the point where, in operational use, the OBOGS would be serviced or replaced, and what is seen then will help DOT&E determine if the system is performing as required. This will be measured against “lessons learned from several fighter aircraft mishaps” in the past related to OBOGS.
The Automatic Ground Collision Avoidance System is another known issue. Fighter aircraft employ AGCAS to prevent loss of life during sustained high-G maneuvers, which can cause the pilot to lose consciousness. While formal requirements for the T-X program didn’t include AGCAS, the program office is working on a strategy to start integrating it by 2026.
Boeing has lost nearly $1 billion on the T-7 program as a result of its delays and issues. The company reported a $500 million loss just this past quarter.