US Air Force replaces turkey baster with 3D-printed TPU tool

The tool was designed by technical sergeant Brandon Branstetter, a crew chief with the 22nd Aircraft Maintenance Squadron at McConnell Air Force Base in Kansas. Maintenance personnel had previously used a turkey baster to add oil to the starter, a process that could allow oil to drip onto the ground and introduce contamination.

“They were essentially using a turkey baster to service the KC-46 engine starter,” said Branstetter. “It was dripping oil onto the ground, and I knew there had to be a better way to solve the problem.”

Branstetter measured the available space and created a digital model of the funnel using computer-aided design software. He then produced the first prototypes on a Bambu Lab H2D 3D printer.

PLA was used for the test pieces, which cost approximately 30 cents each to print. Once the dimensions had been verified, Branstetter selected TPU for the finished tool because its flexibility allowed the funnel to reach the starter within the confined working area.

“Once I got the dimensions of it, I modeled it up in CAD and then decided to print it out of TPU after finding out the dimensions were correct,” Branstetter said. “We made it out of TPU because it is oil and fuel resistant, so it won’t break down after continuous use.”

The funnel required an unusual geometry, extending across surrounding components while remaining angled towards the filling point. The Air Force said no commercially available funnel offered the necessary shape and maneuverability.

“It was a real specific design because of how the funnel needed to go across, but still be angled to where it could reach,” Branstetter said. “It just had real specific and challenging dimensions.”

Each finished TPU funnel costs between $2 and $3 to produce. According to the Air Force, the tool has substantially reduced oil spillage and the risk of contamination during maintenance.

Although developed for a particular task on the KC-46A, the project is also being used to demonstrate the potential for additive manufacturing at McConnell. Its Innovation Lab can produce prototypes, replacement parts and specialized tools locally, without waiting for a commercially manufactured component.

“Almost any job can benefit from 3D printing,” Branstetter said. “It’s a cheap and convenient way to make readily available items to improve productivity.”
The KC-46A Pegasus, manufactured by Boeing, is used by the US Air Force to refuel military aircraft in flight and can also carry passengers, cargo and medical patients.

Photo: a KC-46A on a refuelling mission (© Boeing)