An unknown number of new F-35s will be on hold as a result of ongoing testing of the TR-3 system, deliveries of which are expected to begin between December 2023 and April 2024.

Starting in July, new-build F-35 Joint Strike Fighters equipped with Tech Refresh 3 (TR-3) hardware will not be accepted by the government until ongoing testing of the system is complete, the Office of the Joint F-35 Program (JPO).

“As we reported to Congress in March, we continue to see the risk of TR-3 delivery being delayed until December 2023-April 2024. Delivering aircraft capable of fighting our warfighters is our #1 priority. The TR-3 provides the computing power that ensures the F-35 remains superior to potential adversaries for decades to come,” JPO spokesman Russ Goemaere said in a statement.

“Starting later this summer, F-35 aircraft coming off the production line with TR-3 hardware will not be accepted (DD250) until the relevant combat capability is validated against our user expectations”. The JPO and Lockheed Martin will ensure that these aircraft are safely stored and protected until the DD250 is produced, ″he added.

Following the first flight test of the TR-3 in January, the F-35 program began integrating the new hardware into production in February and has targeted the first delivery of a TR-3-equipped aircraft for July, according to a recent report from the Government Accountability Office. With further flight tests and evaluations of the system software still to be carried out, Goemaere’s statement confirms that the TR-3-equipped jets that will begin rolling off the production line this summer will be on hold until such tests are complete.

“Our team is fully dedicated to the delivery of TR-3 F-35 aircraft and will continue to work with the JPO on software development, maintaining the highest levels of safety and quality. We continue to deliver aircraft in the TR-2 configuration on schedule,” Lockheed Martin said in a statement.

In March, Lt. Gen. Mike Schmidt, the executive director of the F-35 program, told lawmakers that the JPO’s “80% schedule risk assessment” predicted the TR-3 system would be complete by April 2024, which indicated that that date could slide to the right or left. Lockheed’s estimate, however, was that the TR-3 system would arrive in December 2023, a schedule the company sticks to.

“The joint team continues to work tirelessly on the TR-3, and Lockheed Martin remains committed to delivering the first TR-3 aircraft this year,” the company stated in response to questions from Breaking Defense.

Bottom line: Any F-35 jets coming off the line after July that are expected to be in the TR-3 configuration will be in storage until testing is complete. In the best of cases, according to existing estimates, the term would be about five months; at worst, about nine, or even more if there are delays. (Lockheed continues to build jets in the TR-2 configuration, deliveries of which will continue.)

The TR-3 essentially provides the computing backbone to enable Block 4, a suite of new capabilities for the Joint Strike Fighter with features like improved electronic strike weapons and the ability to carry additional missiles. Development of Block 4 has suffered delays, and the GAO reported last month that its increased costs could not be fully accounted for.

Previously, the F-35 program called for the TR-3 to be available in April 2023, which was a year behind the current schedule.

The F-35 program also recently halted separate deliveries due to a vibration problem known as harmonic resonance in the fighter’s engine, which resumed in March after the JPO ordered a hardware refit. Since then, “more than 45 F-35s” have been delivered to the government as of June 8, according to Lockheed.

Michael Marrow