Part 1 in a Boeing series about the USAF refueling tanker
By the Leeham News Team
January 17, 2022, © Leeham News: COTS is an acronym meaning Commercial Off the Shelf. It’s often a requirement for certain types of aircraft to be used by the US Air Force.
The title is a bit misleading in that in most cases, there is no directly usable off-the-shelf product, but instead, a jumping-off point that saves a tremendous amount of development. In aircraft procurement, many things have been bought this way. The advantage to the Air Force is that they get a known flyable aircraft that is for the most part debugged and has an operational history that allows the Air Force to estimate the maintenance burden and training requirements. It shaves years off the acquisition process and can be a very cost-effective way to gain new capabilities.
One of the earliest COTS aircraft procurement programs was the T-41 Mescalero. This was a single-engined piston trainer used for pilot screening at basic flight training. The T-41 was a COTS purchase using a Cessna 172 as the jumping-off point for the design. In 1964, T-41A production commenced. Four different T-41models were built totaling 756 units for the USAF with many of them supplying small air forces around the world as a trainer. There were a few changes made between the Cessna-designed airplane and what the USAF wanted. All of them got jettisonable doors and a bigger diameter nosewheel. Later models got a larger engine from a Cessna 182. It was a simple way to get the USAF what it needed. It found a good jumping-off point that was already designed, proven, supportable, had a fairly defined unit cost, and could use existing civilian maintainers in addition to Air Force personnel. It served as the USAFs basic pilot screening aircraft from 1964 to 1996. From these simple beginnings, other COTS aircraft programs evolved.
The COTS process for the T-41 program was simple.
COTS for the KC-46A
So, let’s see how this works for the 767 to KC-46 COTS program.
The first step in creating a COTS program today is to understand the United States Munitions List, ITAR (International Traffic in Arms Regulations), and how these things impact a COTS program. The US Munitions List is a list of all things deemed to be weapons, weapon components, ammunition or technology that advances the ability of a foreign entity to produce the same. The list is very comprehensive and runs literally thousands of pages. Aerial Tanker Aircraft are specifically listed, as are components in it like the Boom, Electronic Countermeasures, and hundreds of other items.
ITAR is the set of regulations on how contractors must protect these things from inadvertent export to foreign entities not subject to an export license. At the highest and simplest view, it requires you to separate the production facility components and data from anyone that is not a US Person. This requirement is not only the responsibility of the prime vendor but all sub-tier suppliers of program components and data.
US Persons are US citizens and foreign nationals with authorized residency. Unauthorized Exports can be either Hardware or Data and the rules are so complicated that you can export items without leaving the state or country you are in. Compliance is complicated, expensive, and mandatory. The result of ITAR compliance on the KC46 was the separation of the tanker design data into its own repository accessible to cleared workers as well as the separation of the production bays by fences with badge-controlled access.
ITAR complicates life at every turn. Boeing has done factory segregation before on the 737-based P8 line in Renton, so its implementation process was known. But it still forced large factory changes in the Everett Factory and the creation of a delivery center where 767-2Cs were converted to KC-46s.
The first step in the COTS process is to find a candidate aircraft. Boeing offered the 767. It’s been in production for a long time, was built in three different fuselage lengths, with and without cargo doors, with different wings having different wing spars, avionics, auxiliary fuel tanks, and a myriad of other possibilities.
Virtually none of the previously built 767s made a suitable starting point since much of the primary structure for the KC-46 would be unique. Boeing, to comply with COTS, needed an FAA-certified 767 derivative that the USAF could use as the KC-46 feedstock. Boeing created the 767-2C as a paper airplane representing the jumping-off point. This added a bit of complication to the process, as it needed to be test flown and certified to meet the contractual requirement of COTS before they could build it up into a tanker.
Now the process looked like this
After Boeing won the KC-46 contract, it needed to build the 767-2C to create the COTS airframe that would be the jumping-off point for the KC-46. Until now, it had been a bit of a cart before the horse exercise in that Boeing sold a notional aircraft that didn’t exist as a jumping-off point for the tanker. Having won the contract, Boeing needed to go from a paper airplane to an FAA-certified aircraft as the first step in the process.
Boeing’s Designers went to their Lego-like library of previously built 767 airplanes, grabbed the closest stuff that would work as a starting point, and redrafted those drawings into new structures drawings for the 767-2C. Along the way, it stuffed as much Tanker Specific unclassified structure into the airplane as possible. After a huge effort producing the appropriate drawings, Boeing ended up with the design for a big cargo door 767 freighter with large belly fuel tanks, new engine nacelles without thrust reversers, an air-to-air refueling receptacle in the cockpit roof, and a boom operators position without a boom.
Those were the big structures changes. There were thousands of others. The entire electrical system was new because it all needed to be explosion-proof. There was a tremendous engineering package processed to get to the 767-2C. When the uninitiated speak of it as being a modified 767, there is a misunderstanding of the realities of the COTS process. This aircraft shared so little in common with the 767 freighters being simultaneously manufactured commercially on the 767 assembly line that it blurred the lines of “certification by commonality,” a key reason for using the COTS process in the first place.
At the same time, the 767-2C was being engineered, the KC-46 Tanker drawing package was created, and it was huge. All the internal fuel piping was defined. It was all double wall to prevent leaks. The defensive electronics package and the LAIRCOM (Large Aircraft Infrared Countermeasures) systems. The synthetic vision systems for the boomer as well as the boom itself. There was also a large volume of classified stuff being defined, including all the encrypted data link comm systems as well as all the mission software.
But that wasn’t all. All of the maintenance manuals and crew training elements needed to be produced as well as the ground trainers themselves. The scope of this effort is usually missed by those asking why aircraft cost so much. It’s a truly massive undertaking. Training new airmen to become experienced maintainers of the KC-46 requires dozens of volumes of specific instructions showing how every interchangeable part on the airplane is accessed, evaluated, removed, replaced, function checked, closed, and returned to service. Technical Publications never end, as parts are updated, and processes change over the lifetime of the system.
Inside the factory, tanker preparations included isolating the 767 production line from the rest of the factory and creating the ITAR compliance island. A second facility for the conversion of the 767-2C into the KC-46 was built across the field from the factory.
Today Boeing Commercial Aircraft builds 767-2Cs on the Everett Assembly line. These are delivered to Boeing Defense and Space in a tow bar delivery to the BDS completion center. BDS “converts” the 767-2Cs into KC-46A and after completion, redelivers them to the customers (principally the USAF).
Next week: The biggest disappointment in Jim Albaugh’s career