Lockheed Martin has completed the air vehicle critical design review (CDR) for the US Air Force’s (USAF) Combat Rescue Helicopter (CRH) programme.

The CDR allows the programme to move forward in assembling, testing and evaluating the HH-60W helicopter.

The HH-60W CRH is being developed by Sikorsky Aircraft in cooperation with Lockheed Martin.

Commenting on the review, Sikorsky CRH programme director Tim Healy said: "This milestone is an important achievement and demonstrates Sikorsky and the Air Force are well aligned on the technical requirements of the HH-60W.

"We got here by conducting several milestones on or ahead of schedule, and we are committed to staying on that track as we build the first HH-60W aircraft."

Prior to beginning an in-depth design review, the joint Sikorsky and the USAF helicopter programme team generated more than 300 technical documents. It also created and reviewed over 50,000 hardware and software requirements.

The team’s preparatory works also included conducting 17 sub-system CDRs and designing 3,000 new parts.

Sikorsky CRH chief engineer Jim Andrews said: "The team has leveraged digital design tools to generate manufacturing efficiencies that will reduce cost and schedule. This approach will lead ultimately to the HH-60W becoming the first Black Hawk derivative to have a paperless assembly line."

Sikorsky secured a $1.28bn-worth engineering manufacturing and development (EMD) contract from the USAF in June 2014 for the delivery of four HH-60W helicopters, aircrew and maintenance training systems.

The contract also includes development and integration of the next-generation combat rescue platform and mission systems.

"The team’s preparatory works also included conducting 17 sub-system CDRs and designing 3,000 new parts."

In January, the USAF exercised a $203m contract option with Sikorsky to provide five additional aircraft, bringing the total number of HH-60W helicopters to nine.

The HH-60W, which is an advanced variant of the UH-60M Black Hawk helicopter design, will replace the USAF’s ageing fleet of HH-60G Pave Hawk helicopters.

Powered by GE T700-701D engines, the CRH aircraft includes an advanced tactical mission kit integrating multiple sensors, data links, defensive systems, and other sources of intelligence information for use by combat rescue aircrews.

The team will conduct training systems CDR in September.

Image: Artistic rendering of the USAF’s combat rescue helicopter, designed by Sikorsky. Photo: courtesy of Sikorsky.