The US Air Force Life Cycle Management Center’s B-2 Program Office works to ensure the aircraft stays relevant and in the fight for years to come (and those years may come soon, judging by the recent escalation in tensions around the world). For a low volume fleet such as the Northrop Grumman B-2, aka Stealth Bomber, with no more than 20 aircraft flying, AM offers clear and evident benefits, such as in the recent work on the AMAD cover.
In an effort to prevent the unintentional activation of the airframe mounted accessory drive (AMAD) decouple switch located in the cockpit of the aircraft, the program office recently developed a permanent protective cover. Said cover was created using additive manufacturing technology (sources indicate Stratasys’ FDM was used), and it will be placed on top of the AMAD decouple switch, which is a four-switch panel that controls the connection of the engines to the hydraulic and generator power of the aircraft.
“This part [AMAD cover] is unique, and there was never a commercial equivalent to it, so we had to develop it in-house,” said Roger Tyler, an aerospace engineer with the B-2 Program Office. “Additive manufacturing allowed us to rapidly prototype designs, and through multiple iterations, the optimum design for the pilots and maintainers was created. We have completed the airworthiness determination and are currently in the final stages to get the covers implemented on the B-2 fleet, which will be the first additively manufactured part to be approved and installed on the B-2.”
Tyler added that the cost for a total of 20 covers was approximately $4,000 and that the goal is to get them on B-2s by the end of the year or early 2021. The final development of the covers was aided by the Additive Manufacturing Design Rule Book, which was created by the AFLCMC Product Support Engineering Division.
“The rule book provides design guidelines and lessons learned in the additive manufacturing field, specifically the use of direct metal laser melting and fuse deposition modeling technologies,” said Jason McDuffie, Chief, Air Force Metals Technology Office within the Product Support Engineering Division. “It has been used to help create a variety of important parts for the Air Force.”
“Additive manufacturing is the way of the future,” Tyler added. “The B-2 is a low volume fleet. There’s only 20 of them, so anytime something needs to be done on the aircraft, cost can be an issue. But with additive manufacturing, we can design something and have it printed within a week and keep costs to a minimum.”
Perhaps one of the most fascinating aspects of using 3D printing is that the technology ultimately used by theAir Force follows the same basic principle as that used in the educational field. In fact, the initial concept for the cover was created as part of a 2019 project reported by Air Force Technology. Whiteman AFB approached Knob Noster High School and community partners to work in collaboration to develop the solution for the AMAD cover.
Stealth pilots and high school students collaborated, using 3D printing to create the first models. The innovative part was developed in response to a recognized potential issue within the B-2, which forms the core of the stealth mission at Whiteman Air Force Base (AFB). “We wanted to make sure that these switches were protected. I had a feeling if we tapped our community partners, they would work hand-in-hand with our airmen,” said Whiteman AFB 509th Bomb Wing commander brigadier general John Nichols.
The aim was to design a cover with an optimal customized fit that would not come loose during flight. In addition, the focus of the design was on ensuring the pilots can see the switches beneath the cover. Knob Noster High School Stealth Panther Robotics students, assisted by B-2 pilots, drafted a variety of prototype designs and printed them on the school’s 3D printer.
Once the prototype was completed, it was sent to the B-2 simulator for testing. The process leading to the final printed cover involved eight structurally different designs. The robotics team incorporated feedback from the pilots and made small modifications to ensure the cover could be easily gripped and removed. In addition, the cover was designed to withstand the pressurization and heat requirements of the flight.
Following testing and approval, the AMAD panel cover is now in use in the USAF B-2 stealth aircraft fleet