Bell Helicopter is building a new demonstrator aircraft to prove the OH-58D Kiowa Warrior can remain a viable, long-term option even as the US Army seeks a huge boost in performance.

Inside Bell's Xworx advanced programmes group, a re-acquired 206B1 JetRanger is being heavily modified. First, the aircraft will be converted into the OH-58D design on which the 206B is based.

Then Bell's staff will install a new engine with 50% more power than the 650shp Rolls-Royce Model 250 CR30. Honeywell has provided a 975shp HTS900-2, the engine originally built to power the now-cancelled Bell ARH-70 armed reconnaissance helicopter.

With the extra power, Bell's Xworx team hopes to show the army that the OH-58D can be upgraded to meet the army's potential demand for an aircraft that can hover out of ground effect at 6,000ft on a 35ºC (95ºF) day.

Michael Miller, executive director of Bell's military aircraft operations, believes the engine upgrade will allow the Kiowa Warrior to meet the army's target for hover at altitude. However, integrating a more powerful engine may not help the helicopter achieve the army's possible endurance goal of 2h45min.

"I don't think it will hit that" performance target, Miller says.

But Bell wants to prove that the OH-58D has the growth capacity to approach the army's emerging needs for a more powerful scout helicopter.

Integrating the HTS900-2 engine requires other major changes for the OH-58D, Miller says. For the demonstrator, Xworx is integrating the transmission from the 407 and the tail rotor from the 427 helicopters. The engine cowling for the HTS900-2 also is significantly larger.

Miller declined to provide a timeline for first flight of the demonstrator. A tour of the aircraft on the shop floor at Xworx showed that the cabin structure is nearly complete, but the engine, power system and cockpit systems have not yet been integrated.

The full-scale demonstrator - a first for Bell in several years - will join several candidates for a possible future army contract.

The army is still considering options for an armed aerial scout (AAS) helicopter that may replace the OH-58D. An analysis of alternatives is scheduled to be completed by April 2011.

The Kiowa Warrior remains in heavy demand in operations in Afghanistan and Iraq, but the type's limits are showing. The OH-58D was introduced in the early 1980s as an interim scout helicopter, but two attempts to replace it with the RAH-66 Comanche and ARH-70 Arapaho have failed.

Meanwhile, EADS North America has teamed up with Lockheed Martin to offer the AS645 scout helicopter, which is based on the Eurocopter EC145. Boeing also has proposed the stretched AH-6S Little Bird. Sikorsky, however, is offering the high-speed X2 compound helicopter.

Source: Flight International

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