Boeing leads two programs overhauling Air Force's oldest operational bomber

By Shelley K. Mesch / June 1, 2023

(Editor's note: This story has been updated to reflect the correct designation of the Rolls-Royce commercial engine and the location of the adaptive test bed.)

OKLAHOMA CITY, OK -- In a cavernous manufacturing bay here, Boeing engineers can climb inside and around a B-52 Stratofortress bomber the Air Force loaned to the company from the boneyard.

Having an actual aircraft on hand is allowing Boeing to more quickly and accurately identify problems and solutions for the two major overhauls of the nuclear bomber the company is heading, Boeing Senior Director of Bombers Jennifer Wong told reporters. Boeing and one of its partners for the overhaul Rolls-Royce paid for reporters’ travel and lodging for facility tours in Oklahoma City and Indianapolis last month.

Through the Commercial Engine Replacement Program and the Radar Modernization Program, the Air Force will be updating the B-52 to keep it relevant for modern and future fights, said Col. Louis Ruscetta, B-52 senior materiel leader. Though it first flew in 1952, the modernization programs are meant to keep it flying into the 2050s.

B-52s will operate within a two-bomber force structure once the B-1 Lancers and B-2 Spirits are replaced by the B-21 Raider, which is currently in development by Northrop Grumman. Officials have said that aircraft is set for its first flight later this year.
The structure is designed for B-52 to operate from a long-range standoff position while the stealthy B-21 is able to penetrate contested airspace and operate inside a theater, Ruscetta said.

CERP and RMP modifications are planned to be completed during each aircraft’s scheduled time in depot, he said. Currently, a B-52 is kept in the depot for about 230 days, Ruscetta said. That timeframe will extend, but the goal is to keep it within about 10 months, he added.

The CERP-modified aircraft will be designated as B-52J, officials announced last year.

CERP will remove the eight TF33 engines to replace them with new Rolls-Royce-made F130-200 engines that are modeled off the company’s BR725s. This will make them more powerful and more efficient, executives say.

The TF33 engine has served the B-52 well since the 1960s, Ruscetta said, but its age has made it unsupportable. The engines have hundreds of parts that are no longer in production, he said, making maintenance a struggle.

Along with new engines, CERP modifications include new wiring, hydraulics systems, displays and more.

“In order to perform all the necessary mods of this program,” Wong said, “we are touching more than just the engine.”

RMP will replace the radar suite on the B-52 with a “fighter-like” system for navigation and targeting, Wong said.

The new radar will be similar to the Active Electronically Scanned Array radar used on the Navy’s F-18 Hornet, Wong said. Boeing, Raytheon and the Air Force began installing the first AESA system on a B-52 late last month.

The radar operators’ station will also be updated with large touch screen displays to go along with the advanced capability, Wong said.

“While CERP is extremely important, and obviously B-52J gets a lot of attention,” Ruscetta said, “this is probably one of the most critical programs that we’re doing and upgrades that we’re doing to make sure that this is combat effective.”

Initial operational capability for RMP and CERP are still on track for fiscal year 2027 and FY-30, respectively, Ruscetta said.

Integrating commercial engines

The family of engines the F130 is based on has logged more than 32 million flight hours, Rolls-Royce F-130 Program Director Scott Ames said. The years of operation for these engines will make maintenance easier than it is now with the out-of-production TF33s, he said.

“They’re going to be in operation beyond the B-52’s lifecycle,” Ames said. “We’re still producing BR engines today, and so that really sets the supply chain up for maintainability.”

The engine is not-handed, meaning it can be changed from a left-handed pod to a right-handed pod when needed, Ames said. The F130 can be changed by maintainers in about 90 minutes, Ames said. This no-handed approach means spares can work on all engines rather than needing different parts for each engine.

Less labor will also be needed for the maintenance, Ames said.

“It’s all designed to keep the engine on-wing and really keep the aircraft ready to go,” Ames said.

CERP is expected to reach a milestone B decision this fall, Ruscetta said. The program is currently a Middle Tier Acquisition but will move to the major capability acquisition pathway after that decision.

As an MTA program, CERP doesn’t yet have a baseline, Ruscetta said. Previous congressional concerns about cost overruns had been taken out of context or overstated, he said. 

“The projected cost of the program has increased in the last couple of years,” Ruscetta said, “as we know more and as it grows into its early phases we understand more [of] what’s going on.”

A Defense Department estimate sent to Congress in the fall put the bill at about $11.7 billion.

The companies and the Air Force are planning for a critical design review in January, Ames said.

At NASA’s Stennis Space Center in Mississippi, two of the CERP engines are being tested side-by-side in the dual pod that will mount them to the wing, Ames said. The testing structure uses a scissor lift to simulate where the ground would be in relation to the mounted engines, he said, and it can also simulate crosswinds to see how those would affect the engine.

“You don’t really see a lot of dual-pod configurations,” Ames said, “so we want to make sure all our modeling matches what the physics are of the situation.”

The team is about a third of the way through gathering its data points for these F130 tests, Ames said, and that data has so far been consistent with the digital modeling by both Rolls-Royce and Boeing.

The team built in extra time as a buffer for physical testing in case the digital models were off, but Ames said it doesn’t seem like that time will be needed. With that additional time, he said, they will likely run more tests to ensure more de-risk work can be done on the front-end of the program.

Ahead of CDR, the team is already working with a Wright-Patterson Air Force Base, OH team to ensure there are “no surprises” when the time comes, he added.

A “dress rehearsal” of the CDR is planned for this fall, Ames said.

Next calendar year, the engine and Boeing’s auxiliary systems will undergo a software test, and the engine will be run through a freezing-fog test in Tullahoma, TN, Ames said. A durability test will be run in 2025.

Automotive industry influence

At the Rolls-Royce Turbine Super Cell manufacturing facility in Indianapolis, where executives gave reporters a tour, small engine parts ride on individual vehicles around the floor on thousands of feet of track. Each part is methodically tracked as robots bring the parts to machinists, measuring equipment and automated grinders.

The Super Cell is modeled after automotive manufacturing process, adding an efficiency not seen in other aerospace plants, Director of Assembly and Test for U.S. Defense Warren White said. On top of the digital thread tracking parts and the automation moving them around, the company has made major investments in technology to ensure each part is perfect.

The cutting machines physically scan each cast piece before grinding the pieces within 1,000th of an inch of specificity, White said. These machines can adapt to the pieces, cutting them into the proper shape, even if they aren’t loaded into the machine perfectly.

While it may seem like a human solution could solve the problem without the expensive machinery, White said, the small, intricate pieces can be difficult to place exactly the right way each time. And with the high costs of each part, the cost of the new machinery balances out.

“Each of these types of parts [is like] a Mustang or a Corvette. That’s how much they cost,” White said. “Getting one wrong is like my kids totaling it.”

Rolls-Royce has invested $40 million into creating its F130 assembly line, White said, with 30,000 square feet dedicated to the program. The facility will be production-ready in 2027, he added.

Not all of the F130’s parts will be built in Indianapolis, but the engine will be assembled there.

Rolls-Royce is planning to be able to assemble two per week, White said, but the factory will have the capacity to build up to six per week. That extra capacity could be used to speed delivery, he said, but it could also be adapted to build other defense or commercial engines.

“I flex capability already,” White said. “That’s nothing unnatural for us.”

Part of the $40 million being invested in an adaptive test bed, White said. It will be used for future B-52 engine testing, but it will also benefit other programs, such as the Army’s Future Long Range Assault Aircraft program that Textron’s Bell is partnering on with Rolls-Royce.