What do you do when a crack in your F/A-18 requires a million-dollar fixrepair and six months of labor? Send in the 3-D printer.

Fleet Readiness Center Southwest, an aviation repair shop based at Naval Station North Island, California, is home to three state-of-the-art 3-D printers, a technology that can rapidly fashion custom parts. Those initiatives are transforming fleet maintenance: different machines. Here are some ways they're solving problems now, and how they could be used in the future:

1. Multiple platforms. The machines arrived two years ago thanks to Gabe Draguicevich, manufacturing deputy program manager, who saw an unfulfilled line in his budget for additive manufacturing — the technical term for 3-D printing.

Rather than spend the $1.2 million on one machine, he divided it up among three, all printing in plastic:

  • A stereolithography machine, which uses a laser to carve an item out of liquid resin.
  • A fused deposition modeling machine, which builds items drop by drop, like a hot glue gun.
  • A selective laser sintering machine, which bonds powdered material together to make a solid item.

2. Rapid fixes. In 2012, Northrop Grumman and Naval Air Systems Command were testing the X-47B unmanned jet's landing capabilities and observed at Naval Air Station Patuxent River, Maryland, when they realized the aircraft's tailhook was bouncing over the arresting cable instead of latching on. The hook point wasn't a good fit, requiring a new design.

"Northrop came back and said, 'Well, at minimum it's going to be eight months. It could be as much as a year before we can create a new part,' " Draguicevich recalled.

It was costing the program about $250 a day to wait around for the next test, so NAVAIR went to FRCSW, whose engineers elongated the hook point's nose and printed it up overnight on their stereolithography machine. They sent the plastic model to Pax River, which tested it and sent it back for some modifications. Once it was perfect, they carved it out of metal and sent it to NAVAIR.

"In five weeks we did the whole project, start to finish," Draguicevich said.

3. Legacy upgrades. The 3-D printers have also come in handy for updating old F/A-18A-D Hornets, which some have likened to fixing classic cars. FRCSW commanding officer Capt. Tim Pfannenstein likens to classic cars, with unique parts and expensive repairs.

As FRCSW works to extend the Hornets' airframe life from 6,000 hours to 10,000, multiple jets have shown up with a bulkhead crack that would cost about $1 million and 2,000 labor hours — about six months to replace, FRCSW spokesman Mike Furlano said.

Instead, the 3-D printing team came up with a tub fitting to reinforce the bulkhead, modeled with a 3-D printer and then manufactured in-house from aluminum. That brought the repairs down to $25,000.

"That six months and $1 million, we were able to bring down to about two weeks and $25,000," Draguicevich said.

4. Metal: The future. Vice Adm. David Dunaway, head of NAVAIR, has put out a called for 3-D printing with metal in to have a critical safety item, 3-D printed with metal, in the next three years.

That's a tall order, Draguicevich said. It would require being able to get the parts the same every time, which their machines can't guarantee.

"The brilliance behind what he did — he pressured everybody to look at it seriously and come back with a plan to make it happen, whenever it can happen," he said.

There's also the matter of the material: The Navy's aircraft are made of mostly aluminum, which their printers can't work with, he said. It's possible to print with steel or titanium, but those only make up 5 to 10 percent of an aircraft, he added.

"Our role as leaders is to challenge our employees to find creative solutions to warfighter needs," Dunaway told Navy Times in a March 18 statement. "As part of NAVAIR's initiative to adopt innovation as a standard practice, we occasionally set goals to inspire our talented workforce's efforts to apply rapidly evolving technology in achieving those solutions."

Draguicevich said he thought it might be more realistic to be testing with metal parts in three years, maybe fielding them in five to seven years.

5. In the fleet. 3-D printing's most practical application would be on a ship, Draguicevich said, where sailors could print bits and pieces like caps, screws and medical supplies that often run low underway. Sailors on the amphibious assault ship Essex in 2014 fashioned deck drains and oil caps with their 3-D printer as part of the fleet's first test.

However, printing the parts that you might otherwise get from supply requires a stable environment, he added — the pitching and rolling of a ship at sea could mess things up.

"When we talk about 3-D enterprise, the amount of parts that are going to be 3-D printed in the future are probably less than 10 percent," he said. "Probably more like 2 to 5 percent."