Graham Warwick/WASHINGTON DC

Rolls-Royce has postponed efforts to develop a replacement for the Allison 250 based on a low-cost industrial gas turbine (Flight International, 25 February-3 March, 1998).

The so-called World Engine programme is "on hold", says vice-president, customer operations Tommy Thomason.

"We found we couldn't combine the industrial and aerospace markets because they require different levels of qualification," he says.

Allison began the programme because it saw an emerging market for small industrial gas turbines to provide emergency power for businesses. It thought the low-cost design attributes required would apply equally to aero engines.

The World Engine project would have made extensive use of ceramics. The work required to certificate such an engine for use in aircraft proved so different to that required to qualify a ground power unit that the combined project was deemed unfeasible, says Thomason. "We have plans and alternatives to replace the 250," he adds.

"The perfection of the 250 is nigh, and a replacement is required. We have three to four years before it has to be in place."

The latest 250, the -C20R/S "Super R" , is close to certification. The 335kW (450shp) turboshaft incorporates aerodynamic and materials improvements that increase available power, reduce fuel consumption and improve durability, says R-R.

Source: Flight International