Reselection of the CSAR-X combat search-and-rescue helicopter has been pushed back to October, as the US Air Force prepares to release yet another amendment to the request for proposals in its much-disputed $15 billion competition.

Amendment 6 is expected to be released by mid-April, and although the final provisions are not known, bidders expect changes to contract clauses on domestic speciality metals and to programme start and initial operational capability dates to realign the CSAR-X funding profile for a late 2008 contract award.

Boeing won the original CSAR-X contract with the HH-47 Chinook in November 2006, but subsequent protests by Lockheed Martin and Sikorsky forced the air force to reopen the competition in late 2007 with Amendment 5 to the RFP, and new, clean-sheet bids were submitted in early January. The USAF says the protests have potentially delayed IOC from the third quarter of 2012 until the second quarter of 2014.

All three bidders have used the extra time to improve their offerings. Lockheed has made changes to reduce risk, which was evaluated as a weakness in its original bid. The company is offering the HH-71, based on the AgustaWestland AW101 and drawing on the US Navy's VH-71A Presidential helicopter programme. Changes to the HH-71 include dropping the uprated 3,000shp (2,235kW) engines originally offered and staying with the 2,500shp engines now flying in the VH-71A. "The risk is removed," says Dan Spoor, Lockheed's vice-president, CSAR-X programme. Performance is maintained by using improved BERP IV rotor blades.

Spoor says one of the changes to the RFP was to require bidders to demonstrate the technology readiness of the initial Block 0 CSAR-X. At the time of the original bid, the BERP IV blade had not flown and modelled data was submitted. Now the improved blade has been tested and is in production, he says.

AgustaWestland has also conducted aerial refuelling test flights using a probe-equipped UK Royal Air Force EH101 Merlin HC3. Aerial refuelling is a CSAR-X Block 0 requirement, says Spoor, and the demonstration flights using an Italian air force Lockheed C-130J tanker/transport were conducted with first BERP IV, then BERP III blades.

Lockheed has also dropped plans to build HH-71s in the USA at Bell Helicopter. "We have proposed a low-risk plan to meet the USAF schedule using hot production lines, and have a plan to transition that production according to customer requirements," says the company.

Sikorsky, meanwhile, has modified its CSAR-X bid to both increase the capability and reduce the risk of its proposed HH-92. The biggest change is adding a fifth rotor blade - originally planned for the upgraded Block 10 CSAR-X, but now brought forward to Block 0. The modified design has not flown, but the company says it has ample experience with five-blade rotors.

Since its original bid was submitted, Sikorsky has flown the fly-by-wire system planned for the HH-92 - the only FBW helicopter in the competition. The company has also dropped Boeing as its mission-system integrator and will use Rockwell Collins for all avionics and simulators, reducing the software required by 25%, it says.

Boeing is tight-lipped about possible changes to its HH-47, which was ranked highest performing and lowest risk in the original competition. But the company may have conducted additional risk-reduction work on rotor de-icing, which is not installed on any Chinook but is certificated on the competing AW101 and S-92.

Source: Flight International