Thinking outside the box

December 18, 2017

Marine Corps Air Station Miramar, Calif. — Often times Marines are told to think outside the box, and for Capt. Christopher R. Preusser, the Marine Aircraft Group (MAG) 11 aviation safety officer, that old adage came naturally.

“I don’t recall exactly how I came across 3D printing, but when I did, it sparked an immediate interest and blossomed from there,” said Preusser, who built a quick-charge docking station (QCDS) using a 3D printer, plastic and wiring. “So when the program gained attention, I had already been experimenting with 3D printing, or additive manufacturing, at my house and built my own 3D printer.”

According to Preusser, the docking station he built is capable of charging multiple slam sticks, which are a pressure-measuring device required by all Navy and Marine Corps F/A-18 tactical aircraft and training units that fly the T-45 Goshawk aircraft. The device measures ambient pressure within the cockpit, and in the event of a decompression, it will capture all of that data—whether it’s a small fluctuation or a swing to a substantial or rapid loss of decompression. 

“Then, once the aircraft is back to home station or wherever it lands, [personnel] can pull that data from the device and it will all be used to triage the aircrew. The flight surgeon and medical professionals will be able to identify how many atmospheric pressure differences the aircrew were exposed to, and that data will be used to identify which dive chamber to put [aircrew] in,” Preusser continued. “Additionally, based off information gathered, maintenance personnel can then use the data to troubleshoot a suspected component in the aircraft or the environmental control system to help identify what was the causal factor in losing pressure in the cockpit.”

U.S. Navy Naval Air Systems Command established the requirement for legacy tactical aircraft, including the Hornet and Super Hornet, to operate with a slam stick.  

More than a year ago, MAG-11 squadrons received 12 slam sticks for the purpose of collecting cockpit pressurization data. Each slam stick had an associated 3-foot long USB cord, which did not come with a wall outlet to connect to a power source so it became a disorganized mess of cords within the sections that controlled the program. This exacerbated the lack of accountability and inventory of the slam sticks, which also made it very difficult to maintain a charge to all of the devices, Preusser explained.

As a way to mitigate issues and streamline slam stick chargeability, Preusser designed a docking station with 12 charging ports that use one cord to connect to a power source. It’s similar to the shape or design of an engine block. 

“The docking station is printed upside down, and the charger itself is one piece with 12 smaller USB cords woven inside and linked to its specific chamber. It’s easy to put together,” said Preusser, who has printed six docking stations which are currently used by all of the squadrons along the Marine Corps Air Station Miramar, California, flight line, and soon to include Air Test and Evaluation Squadron (VX) 9. “The time it takes to build varies based on detail desired, but the standard design takes about 50 hours of continuous printing at .1 mm levels.”

Marine Fighter Attack Training Squadron (VMFAT) 101 has approximately 58 aircraft and is currently using two of Preusser’s QCDSs to charge its 24 slam sticks, and according to Chief Petty Officer Keenan L. Elsen, who is the lead CPO for maintenance control with VMFAT-101, because the squadron has a large amount of aircraft having the docking stations is more efficient because they now have one charging point, which has made getting slam sticks ready for use much easier. 

Elsen has worked with Preusser since the implementation of the program and has acknowledged the significance to using the slam sticks during flight operations, “we can track cabin pressure exactly to the second and know exactly what is the pressure of the cabin, and it will go the whole flight so if anything pops up, we’re able to figure out what is causing it.”

Preusser also noted fthe endless possibilities with the design of his docking station with regard to readability, “if this device is tailored with an external USB port coming out of it so it could be connected to the maintenance computer, all of the slam sticks would be networked to that computer at once. Software is developed now on the maintenance computer so as soon as the slam sticks are plugged into it, it will automatically pull that data, make any needed software updates or give it a new GPS time hack.”

Through his imagination, ingenuity and interest in additive manufacturing, Preusser used auto-computer-aided design (CAD) software to model and design all of these units but what inspired him was his desire to produce something that people could benefit from.

“I saw this as an opportunity to tinker with something I knew people would use, and it would benefit them,” said Preusser. “If you can think it, draw it, design it, you can print it, and I enjoy doing just that.”