An aerial refueling capability for the E-2D tactical airborne warning aircraft has passed a critical design review, Northrop Grumman said.

The review involved Northrop Grumman and the U.S. Naval Air Systems Command presenting various aspects of the AR system's technical development to a technical review board for evaluation and passing it paves the way for installing AR capabilities aboard the E-2D AHE for flight testing.

"CDR is the last major design milestone where we still have an opportunity to influence the AR system design," said the program's Technical Director Tom Maratta. "These in-depth assessments cover all the key aspects, including management, engineering, and logistics, to ensure we're on the right path to field a usable and supportable capability for our fleet operators and maintainers."

Northrop Grumman was given a $226.7 million contract by the Navy for engineering, manufacturing and development contract for upgrades to the aircraft that would be necessary for an AR capability. Among them: modifications to the fuel system to accommodate a refueling probe, long endurance and field-of-view-enhancing seats, formation lights to improve visibility and air space orientation between the E-2D AHE and its refueling tanker, and enhancements to the plane's flight control system software.

Northrop Grumman said with passage of the design review the first E-2D AHE test aircraft will be sent to Florida later this year for installation of prototype AR equipment and instrumentation for flight testing, which will begin in FY2017.