Paul Lewis/WASHINGTON DC
Sikorsky has begun to look at the Rolls-Royce Turbomeca RTM322 turboshaft as an alternative engine to the incumbent General Electric CT7 for potential future growth development of the S-92 Helibus helicopter.
"The CT7-8 meets our requirements right now, but all aircraft grow in empty and gross weight and will need more power, which means sooner or later we'll look at the RTM322," says Tommy Thomson, Sikorsky head of civil helicopter programmes.
Rolls Royce is promoting the RTM322 as a turboshaft, offering the potential to grow up to 2,235kW (3,000shp) providing added margin, particularly in hot and high operating conditions. GE is also looking to further develop the CT7/T700 series, but claims the current 1,788 kW (2,400shp) engine is lighter and offers better fuel efficiency for the existing S-92.
Sikorsky does not anticipate being able to integrate and certify an alternative powerplant for the S-92 before 2006. Its four planned flight test aircraft are fully committed to completing the current development programme, with an initial US FAR Part 29 certification targeted for early 2002.
The programme has been extended by the recent decision to enlarge the S-92's cabin by adding a forward 400mm (16in) fuselage plug and a redesign of the tail. The initial CT7-6-powered flight test aircraft is expected to resume flying shortly with a new lower righthand side horizontal stabiliser.
"We want to verify that's the position we want and maybe adjust the angle of attack," says Thomson. In August, the helicopter will be fitted with a smaller modified vertical stabiliser being made by Bombardier. The fourth flight test helicopter is being fitted with the fuselage plug and the new tail and is due to fly at the end of the year.
The third flying prototype will join the flight test programme next year. The helicopter is being fitted with Rockwell Collins avionics, replacing the Sanders system. Thomson says: "Our plan is to have the three helicopters retrofitted to the same configuration."
Source: Flight International
