The US Army is set to sign an initial agreement with the US Navy to move forward with a requirement for an all new 2,230kW (3,000shp) common engine programme (CEP) to power the Boeing AH-64 and Sikorsky H-60 series helicopters.

An operational requirements document (ORD) has been drafted by the army for a re-engined UH-60X Black Hawk. This is due to be signed within the month once senior staff officers' briefings and a business plan are completed. Funding is being sought to begin work on a CEP demonstrator programme in 2001, which could produce an operational engine within six years. Once funding is approved, a request for proposals is expected to be released to industry within months.

An ORD for a CEP-powered AH-64X is expected to follow within one to two years. "The Apache programme manager is a supporter of the programme. They have basically agreed a need for more range," says the army's Applied Aviation Technology Directorate (AATD).

The AATD is also working with the navy to extend the CEP to the modernised multimission SH-60R and new CH-60 utility machines, and possibly the US Air Force's HH-60Gs. The AATD is planning to sign a memorandum of understanding by the end of November with Black Hawk, Seahawk and Apache programme managers.

The UH-60X ORD lays out for the first time an improved baseline performance that will require an all-new engine development. "We need a 25% improvement in specific fuel consumption [SFC]: there is no derivative available that meets the ORD. We need a new centreline engine to meet the payload range performance," says Sandy Hoff, AATD chief of power systems.

The UH-60X's maximum take-off weight has been raised to 11,800kg (26,500lb), 680kg more than first planned, while the fuel capacity has again been enlarged, from 1,420 litres (375USgal) to 1,560 litres. Minimum requirements for the UH-60X are to carry a 4,100kg external load at least 135km (75nm), or an 11-man combat assault team at least 275km.

This will require a 60% improvement in power-to-weight ratio over the existing General Electric T700-701C turboshaft. The army has also specified a 6,000h overhaul life for the engine, an increase of 1,000h, while seeking a 25% cut in operating and support costs. Proposed growth T700 and Rolls-Royce Turboméca RTM322 engines fall short of this.

There is still some industry scepticism that these requirements can be met even by a CEP. Lower SFC will require higher pressure ratios and temperatures, in turn meaning smaller and more complicated compressors, negating any savings, suggest sources. AATD counters that its Joint Turbine Advanced Gas Generator demonstrator programme has met many of CEP's goals.

Source: Flight International