WASHINGTON — When an F/A-18E/F Super Hornet took down a Syrian Sukhoi Su-22 in June — the U.S. military’s first air-to-air kill in nearly 20 years — it launched an AIM-120 AMRAAM missile, a mainstay of the Navy and Air Force’s weapons inventory since it came online in the early 1990s.

But after decades of continued production, the AMRAAM is facing obsolescence problems, and Raytheon, its manufacturer, has fallen behind on a technology refresh due to problems developing an integrated circuit.

The AMRAAM’s obsolescence upgrade, called Form, Fit, Function Refresh (F3R), affects 15 circuit cards that comprise about half of the missile’s guidance section, according to Air Force documents obtained by Defense News. The key component at fault for the delays is the application specific integrated circuit (ASIC), a processor that will be used to execute the missile’s software, the Air Force confirmed in response to emailed questions.

The Air Force and Navy are hopeful that Raytheon can resolve design issues connected to ASIC, which has required more troubleshooting than expected to meet objectives. However, both services have cut their planned buy for fiscal year 2018 by hundreds of missiles, and a key test has been delayed by more than a year.

Raytheon is responsible for designing ASIC, which will eventually be fabricated by one of the company’s suppliers. No other alternatives for this component exist, the Air Force said.

“There was an issue with one component that was critical to the upgrade that delayed us a bit, and we had to re-plan elements of that,” Mike Jarrett, Raytheon’s vice president of air warfare systems, said during a June interview at Paris Air Show.

While Jarrett said the company had figured out a fix and that “everything is on track,” he declined to specify how Raytheon had solved the problem, citing customer sensitivities.

The Air Force was more loquacious. To bridge production in the short term, Raytheon will need to make modifications to the current navigation assembly, which contains obsolete parts that can no longer be purchased, the service said.

Raytheon is also designing a new simulator to drive down risk.

“Once the simulation has been used to assess performance against program requirements, there will be sufficient data available to make a fabrication go-ahead decision,” the Air Force said.

In the best case scenario, a working F3R guidance section will complete the Interim Test Readiness Review — a key assessment of whether the F3R modifications meet requirements — in January 2019, a full year and a half after the initial July 2017 target date.

That delay effects other key dates. Raytheon will now cut the F3R changes into its production line in FY2019, according to budget documents, with first deliveries taking place in FY2021.

As a result of the lagging progress on F3R, both the Air Force and Navy opted to slow roll their AMRAAM acquisition in fiscal 2018.

Compared to the five year plan put forward with the fiscal year 2017 budget, the Air Force FY2018 budget request includes 183 fewer AMRAAM missiles for that year. The 2017 Future Years Defense Plan (FYDP) shows the Air Force buying 388 AMRAAMs in 2018, but the service ended up requesting only 205 missiles.

The Navy similarly opted to request a smaller number of AMRAAMs in FY18 than it believed it would need in FY17. Its FYDP in 2017 predicted the service would request 247 AMRAAMs in FY18. Instead, it intends to buy only 120 units in 2018 — less than half of its planned order.

Both the Navy and Air Force plan to increase their buy rate in FY19, when the F3R upgrades are slated to be finalized. But in June, Lt. Gen. Arnold Bunch, the Air Force’s top uniformed acquisition official, told Defense News that he wants to see Raytheon improve its performance before increasing funding for more AMRAAMs.

“I need to see the program progress before I would procure more weapons,” he said in a June interview. “It’s very complicated. We know it’s very complicated. [Raytheon is] committed to taking care of it, but I’m just not comfortable right now that I would want to put additional procurement [funds] into it and put more stress on what I’m already trying to do.”

Members of Congress have made note of the lower quantities, but service officials have made clear they have no intention of throwing money at the problem. At a House Armed Services Committee hearing in June, Rep. Tom O’Halleran, D-Ariz., asked about whether issues could be resolved by funneling additional dollars into the program.

“If Congress were to add funding, could it be used to buy more missiles, or are you limited by where things are with the production?” he asked Air Force and Navy officials.

Bunch told O’Halleran that he wanted to see Raytheon work through its difficulties with F3R, before increasing the AMRAAM budget line. 

“Once we get that on track, I’d be willing to come down and ask you for additional help,” he said. “We would love to buy more, sir, but I need them to get the production right because if we buy too many more and run out of parts on the line, then we don’t have the ability to produce [them].”

"From the department of the Navy's perspective, we're in exactly the same place," said Vice Adm. Paul Grosklags, head of Naval Air Systems Command.