Spirit AeroSystems have started assembly of the V-280 Valor fuselage, which is competing for the US Army's joint multirole technology demonstrator (JMR-TD) contract.
Spirit AeroSystems Defence senior vice-president Phil Anderson said: "This is a major milestone for the technology demonstrator unit.
"Spirit AeroSystems is proud to be on team Valor and we are excited to be designing and building the composite cabin and cockpit for the V-280."
Developed with an army-centric design, the Bell Helicopter V-280 Valor is claimed to be capable of providing the combatant commanders with an ability to conduct multiple vertical lift missions with enhanced agility and twice the speed and range of other conventional helicopters.
Offering the best value in procurement, operations, and support, as well as force structure, the helicopter has fewer parts, lowering complexity compared with previous generation tiltrotors.
Bell Helicopter Military Business executive vice-president Mitch Snyder said: "US ground forces require significant increase in speed and range to operate against and strike adversary systems much deeper than existing platforms.
"That is the vision for future vertical lift. The V-280 advanced technology tiltrotor provides the Department of Defense (DoD) with unmatched speed, range and payload for expeditionary manoeuvre to win these future conflicts.
"Spirit AeroSystems beginning major assembly on the V-280 fuselage brings this high-performance aircraft one step closer to completion."
Spirit AeroSystems aims to deliver the first V-280 fuselage to the Bell Helicopter facility in Amarillo, Texas, US, later this year.
The first flight of the V-280 technology demonstrator is expected to take place in the second half of 2017.
A subset of the DoD's joint future vertical lift effort, the JMR programme aims to develop a new family of helicopters with enhanced avionics, electronics, range, speed, propulsion, survivability, operating density altitudes and payload capacities.
Other competitors selected for the programme include AVX Aircraft, Karem Aircraft, and Sikorsky Aircraft-Boeing team.
Image: The first V-280 fuselage will be shipped to the Bell Helicopter facility later this year. Photo: copyright 2015 Spirit AeroSystems.