Diving into Maintenance with NASA’s X-59

In the California desert, as NASA's quiet supersonic X-59 paused between its 11th and 12th flights, mechanic Jonathan Reynaga climbed a ladder to the top of the aircraft. Reynaga strode down the plane's wing until he reached the distinctive air inlet that leads to its engine and stuck his head in.

And then he dove in headfirst, completely disappearing.

The moment, caught on video in the spring of 2026, might seem bizarre to those unfamiliar with aircraft maintenance. But "duct diving" is just part of a regular day at NASA's Armstrong Flight Research Center in Edwards, California.

"It's a pretty normal procedure for aircraft maintenance," said Paul Dees, NASA X-59 deputy propulsion lead. "What they're trying to do is check for any potential damage, any potential foreign objects or debris that could affect engine performance."

The X-59's inlet slopes down toward its single engine, so Reynaga, a general flight mechanic with X-59 contractor Lockheed Martin Skunk Works, had his head lower than his feet as he went in. In a space not much wider than his shoulders, he used a flashlight to inspect the engine's fan blades and other components. Reynaga had to move carefully around special sensors that the research team uses to gather data on engine performance.

He remained in the inlet for few minutes before wriggling out backwards, with another member of the crew keeping an eye on him throughout the process. The X-59 team makes sure its technicians stay safe and avoid overheating.

"It's not a temperature-cool job," Dees said. The X-59 stays in the shade for maintenance, but desert temperatures regularly rise to over 100 degrees Fahrenheit, and the aircraft is still cooling down post-flight as technicians work on it.

The checkup was brief, but vital. Although the X-59 undergoes in-depth maintenance on a regular schedule, a duct dive paired with a visual examination of the aircraft's exhaust after every flight is a good way to quickly assess the health of its engine.

Technicians duct dive on NASA's research jets across its centers. At Armstrong, that includes the aircraft that accompany the X-59 on test flights: an F-15 with deep, rectangular inlets that a person can crawl in fairly comfortably, and an F/A-18 with round, tight, curving inlet spaces that make for a less pleasant experience.

The X-59's inlet has few advantages over the F/A-18, according to Juan Salazar, crew chief for the agency's Low Boom Flight Demonstrator project. It's similar to the F/A-18's inlet in diameter but shallower, making for an easier dive.

Regardless of the aircraft, a human mechanic is still the best way to get the job done.

"Maybe one day there will be something that will replace this inspection, but right now, the best way to do it is to send a person in," said Salazar.

The X-59 has a top-mounted engine, a key design element. The top mount helps the X-59 separate the shock waves that build up on its surfaces during supersonic flight. For traditional supersonic planes, the shock waves trailing the aircraft would pile up on each other as they traveled to the ground, ultimately leaving two that would be heard as a sonic boom. The X-59 prevents those waves from merging, for a quiet sonic thump.

The top mount also means the X-59's engine doesn't pull in the kinds of debris that can get sucked up by more conventional, lower-mounted engines during takeoffs and landings, Salazar said.

All of which means that after 38 flights, the X-59's duct dives have found nothing but a damage-free engine. "And that's how we like it," Dees said.

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