WASHINGTON — The Sikorsky-Boeing Defiant design will not have its first flight in 2018, following a technical issue discovered during ground tests.

Rich Koucheravy, Sikorsky director of business development for future vertical lift, and Randy Rotte, Boeing director of global‎ sales and marketing for cargo helicopters and FVL, revealed the delay in a call with reporters Wednesday.

“We are going to slip our first flight into early 2019. While it’s not necessarily, I’m sure, what a lot of folks would have liked — it’s not necessarily what we would have liked — we continue to build confidence in our configuration,” Koucheravy said.

Road to Future Vertical Lift: Defiant preps for first flight, Valor leaves the nest The two vertical lift aircraft under development for the U.S. Army are making headway on the road to one day delivering a potential future medium-lift aircraft to the joint forces.

The team initially planned for the system to fly in 2017, but that was delayed following an issue with the manufacturing of the system’s blades. (The executives said that issue has now been resolved.)

For months, the expectation had been that first flight would then come before the end of the year. But while running the power-train systems test bed — essentially, a full-scale design of the system that is bolted to the ground — engineers discovered a series of issues that caused them to hit pause on testing the program.

“We have had a couple of small things. I won’t get into the exact pieces, but it required some repairs, just some kind of mechanical repairs,” Rotte said when asked for specifics on the issue that caused the delay. “The latest ones required about two to three weeks of going back in, fixing those pieces, putting them back on the aircraft.”

“It’s nothing that requires a redesign of major components or any of those pieces. it was just, candidly, some interactions that the models perhaps didn’t all capture,” Rotte said, adding that the ground tests should restart sometime in the next week.

× Fear of missing out? Sign up for the Early Bird Brief, the defense industry's most comprehensive news and information, straight to your inbox. Thanks for signing up. By giving us your email, you are opting in to the Early Bird Brief.

The Sikorsky-Boeing team wants to get 15 hours of flawless test results from the ground-based system before that first flight, and the executives indicated the first flight should happen fairly early in 2019.

The Defiant is one of two designs competing for the Joint Multi-Role Technology Demonstrator effort, which will inform requirements for the U.S. Army’s FVL family of systems, which will come online in the 2030s. Competitor Bell’s V-280 Valor tilt-rotor aircraft has been flying since December 2017.