The Air Force must disassemble parts of its own stealth bomber

In a surprising turn of events, the United States government is calling on its nation’s industry to reverse-engineer components of the Air Force’s B-2 Spirit stealth bomber. A formal call for this highly unusual type of assistance went out today on the US government contracting website

Mark Thompsonnational security analyst at the Project On Government Oversight, drew our attention to the note, which is seeking an engineering effort that will reverse engineer key parts for the B-2’s charge heat exchangers. While it’s unclear which part of the aircraft’s many complex and exotic subsystems these heat exchangers relate to, the bomber has no shortage of avionics systems, for example, that might need cooling.


B-2 Spirit refueling at sunset.

The notice Is it that provide details on what he expects engineers to support the upkeep of the silver chip stealth bomber fleet:

“This engineering effort consists of de-engineering the core of the B-2 charge heat exchangers, developing a disassembly process to remove defective cores, developing a stacking, vacuum brazing and welding process to manufacture new heat exchanger cores and to develop a welding process to install the new cores on the existing B‐2 load heat exchangers The requirement includes reverse engineering the annealing process for the load B‐2 heat exchangers Load B-2 The load B-2 heat exchanger (NSN 1660-01-350-8209FW) uses air and liquid ethylene glycol (EGW) water to produce cold air for the Cooling system.

“The deliverables will include all technical data related to disassembly of the heat exchanger, all technical data related to the cores, all technical data related to the stacking, vacuum brazing and installation of the cores on the units The deliverables will also include all technical data related to the tooling required for dismantling, core stacking, core vacuum brazing, post-brazing treatment and core installation. Government B-2 Sink heat exchangers will be provided as Government Furnished Property (GFP) to prototype this effort.The two (2) prototype units will be delivered upon completion of the GFP return contract.The final design shall be meet the test qualifications specified in the Government Engineering Orders (OT) Finally, a qualified repair source must be provided capable of refurbishing the B-2 load heat exchangers to comfort. ment to the aforementioned deliverables.

The second paragraph makes it very clear that this is a classic reverse engineering effort, in which the technology to be copied is provided for analysis before the procedures involved in their original production are replicated.

While it’s hard to say exactly why this approach is being taken now, it does indicate that the original blueprints for these components are either not available or the manufacturing processes and tooling used to produce them no longer exist. This could be because they were kept so secret that at some point they were inadvertently completely destroyed. It could also be that they were simply misplaced, or that the parts were produced by a small contractor who is long gone, taking the custom tooling with him.

US Air Force/Senior Airman Jessica Snow

A B-2 sits on jacks at Whiteman Air Force Base, waiting for Airmen from the 509th Maintenance Squadron to perform checks.

This must also be considered in the context of the unique B-2 fleet sustainment requirements, of which 19 are combat coded and only 20 exist, in total. In this previous function, The war zone examined how the bombers each undergo a scheduled depot maintenance cycle every nine years, including a major overhaul and full reapplication of the aircraft’s special radar-absorbing material skin and paint. It’s a process that already uses innovative processes, such as robotic systems to help install parts and apply coatings, to help improve quality control and reduce the frequency of depot visits.

Of course, recent technological developments potentially make the reverse engineering process much faster and more reliable as well. Earlier this year it was reported that the Air Force’s Rapid Sustainment Office (RSO) was looking to industry for a “state-of-the-art automated 3D scanning system” specifically for reproducing aircraft parts no longer in production, including in depots of maintenance.

US Air Force/R. Nial Bradshaw

A 574th Aircraft Maintenance Squadron maintainer performs depot maintenance on an F-22 at Hill Air Force Base, Utah. The 574th installed the first metal part printed in 3D on an operational F-22 in December 2018.

In the case of scenario B-2, one could imagine how a 3D scanner would be used to scan the original parts and produce a virtual model. From this, at least in part, would then flow a new set of blueprints that could be replicated by machine processes and other current manufacturing techniques, yielding a new source of heat exchangers needed to maintain current.

One of the B-2’s stablemates in Air Force Global Strike Command, the veteran B-52H Stratofortress, also benefited from reverse engineering. In this case, Support Mission Inc. received an Air Force contract to overhaul the aircraft’s engine bypass ducts. With insufficient technical data, the company turned to modern computer-aided design and computer-aided manufacturing (CAD/CAM) technology to ensure that the new components were fitted correctly.

Similar initiatives are already underway within the Air Force. The 402nd Electronic Maintenance Group’s Reverse Engineering Avionics Redesign and Manufacturing team, or REARM, is located at the Warner Robins Air Logistic Complex (ALC) at Robins Air Force Base, Georgia. Its role is to ensure the supply of spare parts for old weapon systems.

U.S. Air Force/Joseph Mather

Damon Brown, 402nd Electronic Maintenance Group Reverse Engineering, Avionics Redesign and Manufacturing chief, with a circuit board for a B-52 that is being redesigned by the team, replacing five circuit boards inside the bomber from the era of the cold War.

“The first part of reverse engineering is to do an obsolescence study,” Damon Brown, 402nd EMXG REARM chief, explained in an Air Force statement. Press release. “If we can’t get or find the parts to repair or replace a piece of equipment, we go back to the customer or the supply chain with that item and ask them what they want us to do.”

Working on behalf of the Air Force Sustainment Center, similar REARM teams are also located at Oklahoma City ALC at Tinker Air Force Base, Oklahoma, and Ogden ALC at Hill Air Force Base, Utah.

Indeed, as the average age of the Air Force fleet continues to increase, it is likely that there will only be such requirements for parts that have long been out of production. Prior to resigning, former Air Force Assistant Secretary for Acquisition, Technology and Logistics Will Roper, Recount
Air Force Magazine of his desire for a “digital representation of every piece of Air Force inventory”.

Alan Radecki/Northrop Grumman

The B-2 “Spirit of Pennsylvania” during a scheduled maintenance stay at Plant 42 in Palmdale, California.

During his tenure, Roper was also keen to increasingly leverage commercial industry practices in this type of military support, with a view to reducing sustainment costs.

“We want to reverse engineer parts that we may not have the designs for anymore,” Roper said. “We want to look at part repeatability so that we are not critically tied to an individual printing machine. And we want to look at the whole process of what it takes to get a novelty manufactured part on a mission critical aircraft or satellite.

Rapid Sustainment Office Advanced Manufacturing Olympics last october saw a lot of 3D printing, but also used reverse engineering. At one event, teams had to replicate as many parts as possible from a box of components using reverse engineering and modeling.

Overall, the search for reverse-engineered components for the B-2 fleet is part of the Air Force’s current trend of moving toward the latest digital engineering and manufacturing techniques to help ensure that its planes can be maintained not only more easily and cheaply, but in some cases perhaps not at all. Above all, it highlights how America’s small fleet of aging stealth bombers, which largely relied on highly experimental technology when they entered service, are a particularly obvious candidate for using reverse engineering for the keep in flight. For something as critical as a heat exchanger, which is essential to keep the jet in the air, these new processes and techniques may have arrived just in time.

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