The US Air Force Has Taken Another Step Toward Re-Engining its B-52s

The service wants to modify each of the 76 bombers and possibly buy more 600 new engines as part of a multi-part deal.

byJoseph Trevithick|
The US Air Force Has Taken Another Step Toward Re-Engining its B-52s

The U.S. Air Force appears to be moving ahead with plans to finally replace the engines on its aging B-52H Stratofortresses on a one-for-one basis, which could give the iconic bombers extra time over the battlefield or additional overall range, all while cutting the costs to fly them per flight hour. Though the project could help the BUFFs remain relevant for decades to come, the service will still need to find the necessary funding and other resources as it struggles to keep other major modernization programs on track and deal with a worrisome shortage of pilots.

According to an announcement Air Force Materiel Command posted on FedBizOpps, the federal government’s main contracting website, the Air Force Life Cycle Management Center’s (AFLCMC) B-1 and B-52 Bomber Division will host meets with industry representatives at Tinker Air Force Base in Oklahoma on Dec. 12 and 13, 2017. The notice stresses that this “industry day” is presently just for market research purposes, but that there is something of a formal plan specifically to buy "commercial" replacement engines.

“The B-52 Re-engine program will replace current B-52 engines with new, commercial-off-the-shelf (COTS) engines for the entire 76-aircraft fleet,” associated contracting documents explains. The Air Force’s present overarching plan is to award two separate contracts for the engines and the modifications necessary to attach them to the bombers’ wings. There is nothing in the existing contracting language prohibiting a single company from securing both deals.

The service did not publicly release any firm performance or cost metrics along with the announcement, though contractors interested in the modification contract will have to supply a detailed cost assessment and potential technical risks in any proposal. However, in August 2017, Boeing released a promotional video outlying the benefits they felt the planes would get from a re-engine effort.

An airmen poses for a picture inside one of the B-52's engine nacelles before getting to work., USAF

The Chicago-headquartered plane maker, which first built the B-52s more than five decades ago, suggested that BUFFs with new engines could be approximately 30 percent more fuel efficient, giving them some 40 percent more flying time, reducing the number of tankers necessary for each sortie, and essentially eliminate the need for costly overhauls.

Though it’s hard to confirm these claims without knowing the exact metrics, we do know that the Air Force overhauls each TF33 every 6,000 flight hours as a rule, a process that costs $2 million per engine. This, on top of fuel costs and more routine maintenance issues for an engine that Pratt & Whitney first produced in 1959, is one major reason why it costs the service more than $70,000 per hour to fly the B-52, making it one of the most expensive aircraft for it to operate.

The Air Force has also not made it clear how extensive it expects the modifications will have to be in the end, either. The initial “statement of objectives” does strongly imply that it is interested in a one-for-one replacement of each of the B-52H’s eight existing Pratt & Whitney TF33 rather than an entirely new configuration.

At present, the Air Force wants potential engine makers to be ready to supply 20 engines at a firm, fixed price in order to modify just two BUFFs and their 16 combined powerplants. This would leave 4 in reserve in case of failures or other issues.

Airmen work on one of the B-52H's engine pods., USAF

This could potentially offer cost saving benefits if the contractor in charge of modifying the aircraft keeps a significant amount of the plane’s existing architecture intact. The B-52s design has the eight engines in four pods, two under each wing. As we at The War Zone have noted many times in the past, the arrangement of the engines, the angle of the bomber’s wings, and other design features, have been a major impediment to previous attempts to re-engine the B-52.

In January 2017, our own Tyler Rogoway wrote:

“The last time the USAF researched what it would need out of an engine program was 2014, when it concluded that new powerplants would need to save between 10-25% in fuel consumption, and would have to go 15-25 years before the first deep overhauls of the engines are required. The question of which engine would best fit this requirement remains, as well as whether four large engines or eight smaller ones (even six, under some concepts) would be best.

“One area of concern is if new pylons would be needed to accommodate powerplants mounted in new locations under the BUFF’s wings. Such a requirement could result in a costly re-engineering of the B-52’s wings. With four larger engines, such as GE's CF6 (called the F138 on the C-5M) or engines similar in size to the Pratt & Whitney PW2000 (the F117, in use aboard the C-17A) wing height and rudder authority for engine-out operations remain a question. As as result, costly flight control and avionics upgrades might be needed to accommodate their use, beyond the need for potential structural upgrades to the B-52’s wings.

“With this in mind, probably the easiest option is eight compact high-bypass turbofans fitted to the aircraft’s existing pylons in re-contoured dual-nacelle pods. The Rolls Royce BR725 powering the Gulfstream 650 is one contender, as is GE’s Passport 20 found on the Global Express 7000 and 8000. If the Air Force decides to push forward with an official RFP for an engine swap on the B-52, other entrants will surely emerge.”

The Air Force’s proposed plan could still leave the door open for offers to simply rebuild or otherwise upgrade the TF33 engines. This is something that Pratt and Whitney has, unsurprisingly, suggested as a possible course of action in the past. Any company going that route would likely have to make its pitch based on an offer of extreme cost savings through minimal modifications to the bomber's airframe over competing proposals involving more efficeitnt all-new engines, though.

Regardless, these basic details point to the potential for a very lucrative deal for whatever company or combination of firms gets the final contract. A one-for-one replacement plan would involve the purchase of at least more than 600 engines just to upgrade each of the Air Force’s 76 B-52H bombers. This would not include spares – at least two per aircraft, or 152, based on the initial purchase plan of 20 engines for two aircraft – and other support services.

US Air Force ground crew members wash the insides of a B-52H's engine pod., USAF

Contracting wise, the Air Force is still working how exactly it might proceed in the acquisition process, though. In the past, senior Air Force officials have suggested they could seek a more complicated, but cooperative public-private partnership with the contractors involved, whereby the company or companies would get paid later as extra funding becomes available from the reduced operating costs. This could enable the project to be effectively cost neutral, but would require a significant leap of faith on the part of the contractors who take part in the program.

But the Air Force did not make any direct mention of this type of contracting process in its November 2017 announcement. At present, it says it is exploring three possible “courses of action.” The service could review proposals for the modifications at the same time as it reviews possible engines through either a one- or two-step procurement process. The other option would be to let the contractor making the changes to the B-52s just choose the motors that best suit its particular integration proposal.

The latter process is notable in that it closely mirrors the controversial method the Air Force chose when it set about upgrading its EC-130H Compass Call electronic warfare aircraft. Over the protests of a number of aircraft makers who felt they would not get a fair chance to pitch their particular planes, the service allowed L3 to pick the actual airframe that would carry the jamming equipment.

However the Air Force proceeds, funding is likely to remain an issue. Any B-52 re-engine program will be competing with a host of other costly modernization efforts, including, but definitely not limited to continued development and testing of the service’s F-35A Joint Strike Fighter, work on the B-21 Raider stealth bomber, continued delays with the KC-46A tanker, and new intercontinental ballistic missiles, and advanced nuclear-capable cruise missiles.

Airmen move a TF33 engine., USAF

On top of that, the service is still suffering from an unprecedented shortage of pilots. Most recently, it has begun offering expanded monetary incentives to try and retain aviators, with minimal success.

What is clear is that the B-52s could greatly benefit from new engines and the costs to operate the TF33s will only keep increasing. Without something like the aforementioned public-private partnership deal, any re-engining could prove to be a costly affair, too.

But if the Air Force realistically intends to continue flying the bombers through 2040, or beyond, it will need to find find a solution to the problem sooner rather than later.

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