Air Platforms

Sikorsky-Boeing team delays Defiant first flight

13 December 2018

The Sikorsky-Boeing SB>1 Defiant team postponed the aircraft's first flight until early 2019 after a pair of undisclosed issues arose during PSTB runs. Source: Lockheed Martin

Key Points

  • Sikorsky and Boeing delayed their Defiant rotorcraft first flight until early 2019
  • Undisclosed issues arose during PSTB testing

The Sikorsky-Boeing team developing the SB>1 Defiant compound helicopter delayed the aircraft's first flight from late 2018 until early 2019 due to undisclosed issues that arose during propulsion system test bed (PSTB) runs over the last few weeks.

"While it is not what a lot of folks would have liked, we continue to build confidence in our configuration," Rich Koucheravy, Sikorsky director of business development for Future Vertical Lift (FVL), told reporters on 12 December. "That is the purpose of the [PSTB], so we discover it off the aircraft and are able to implement the fix."

The team will run the PSTB for additional hours before starting ground runs with Defiant in the next few weeks. Sikorsky and Boeing need 15 hours on the PSTB before being certified to fly.

Randy Rotte, Boeing director of global sales and marketing for cargo helicopters and FVL, said the PSTB is Boeing and Sikorsky's opportunity to experience the whole aircraft configuration as a system. It will show how parts and systems interact on a system level.

Boeing spokesman Jerry Drelling said on 13 December that the PSTB ground test stand was built specifically for the Joint Multi-Role Technology Demonstrator (JMR-TD) test programme to test all systems before flight. He said the Sikorsky-Boeing team successfully conducted a bladed light-off of the PSTB, which represented the first time the Defiant configuration had ever turned.

All systems on the Defiant are tested prior to operation on the actual aircraft. Drelling said nearly all onboard systems have been tested, including hydraulics, engines, fuel systems, electrical systems, avionics, and some electronically actuated flight control systems. Before the Defiant flies, Drelling said Sikorsky and Boeing will ensure successful completion of integration testing and ground test.

Want to read more? For analysis on this article and access to all our insight content, please enquire about our subscription options at

(330 of 584 words)