Work begins to transform MD-90 into NASA’s X-66 Sustainable Flight Demonstrator

Boeing has begun extensive modifications of an MD-90 airplane that will become the X-66 Sustainable Flight Demonstrator. The company has removed its engines and completed 3D metrology scans to inform the plane’s design and build plan.

The MD-90’s original wings will soon be removed to test the Transonic Truss-Braced Wing (TTBW) design with new ultrathin wings braced by struts with larger spans and higher aspect ratios. The TTBW’s wider wingspan and aerodynamic efficiency could significantly accelerate opportunities to reduce fuel use and emissions.

The X-66 is NASA's first experimental plane project focused on helping the U.S. achieve its net-zero aviation greenhouse gas emissions goal. Ground and flight testing is expected to begin in 2028.

With the scanning data, Boeing will use 3D modeling software to overlay the existing MD-90 structure with the new X-66 components, enabling more accurate spatial integration and the opportunity to identify and mitigate risks early in the modification process.