For decades, U.S. Air Force aircraft maintenance crews have religiously followed the “component swap” model. When an aircraft part is worn out, swap it for a new one. It’s a model which works - if you have new parts, time and money available. With all three in short supply,
Cold Spray (CS) additive technology could allow maintainers to renew worn or broken parts while still on an airplane, getting it mission-ready quickly while in the field.
The 28th Bomb Wing at Ellsworth Air Force Base in South Dakota is spearheading USAF efforts to apply CS repairs to operational aircraft. Working with students and professors from the
South Dakota School of Mines and Technology, personnel from the 28th Maintenance Group Additive Manufacturing Flight
repaired an over-wing faring slip joint on an operational B-1B bomber using CS back in May.
The slip joint is basically a part which allows the B-1’s wing to flex vertically. What’s important to recognize is that the repair was done in situ with the joint in place. The standard practice of swapping in a new slip joint would have required the costly and time-consuming removal of the B-1’s wing.
“This would have
normally involved eight weeks of downtime,” says Brian James, a Ph.D. graduate student at Mines and the additive manufacturing chief engineer with the 28th Maintenance Group. “
With cold spray we were able to do this in a couple of hours.”
The B-1B began active service in 1986 and all 100 bombers were delivered by 1988 so obtaining parts is difficult, often requiring cannibalization of another airplane. Combining this with the disassembly required,
to replace the slip joint would have resulted in a $500,000-plus bill for the Air Force. Cold Spray repair of the original part cost a small fraction of that.
