The US Army will consider alternatives to its plan to acquire upgraded Bell Helicopter OH-58F Kiowa Warriors and will now stage a flying demonstration in April with as many as five rival aircraft.

The proposed $8.7 million event, pending approval by the under-secretary of defense for acquisition, would finally clarify whether the army should invest in a more capable aircraft for its armed scout missions or persevere with the OH-58F, the latest version of the almost 45-year-old Kiowa series with an upgraded cockpit.

The army has already ruled out the Sikorsky S-97 Raider from the contest, which came as a surprise to the manufacturer. The high-speed S-97 was launched a year ago and is not expected to reach flight status until 2014, or two years after the army's demonstration. Still, Sikorsky officials believed the army would consider S-97 simulations as part of the demonstration. However, the army emphasised that only off-the-shelf aircraft in 2012 will be considered to replace the OH-58F.

"You don't have an airplane, you don't play," said Maj Gen Tim Crosby, programme executive officer of army aviation.

The S-97's absence leaves a field consisting entirely of helicopters with conventional speeds, but with the ability to hover out of ground effect at 6,000ft (1,800m) density altitude at 35°C (95°F). The OH-58 is limited to a hover at 4,000ft at similar temperatures.

Eligible contenders include the Bell OH-58F Block II concept, which replaces the Rolls-Royce 250 engine with a more powerful Honeywell HTS900. The Block II also adds an upgraded transmission and borrows the rotor blades and tail rotor from the Bell 407.

EADS North America, meanwhile, is offering an armed version of the UH-72A Lakota, the AAS-72X, which includes a mission system integrated by Lockheed Martin.

EADS also confirmed the army has been briefed on the T2, a new version of the Eurocopter EC145 - the base model of the UH-72 - with a fenestron and a more powerful engine.

Another known competitor is the Boeing AH-6 Little Bird. Boeing is close to completing the first international sale of the AH-6i, which adds a sixth blade and new avionics based on software developed for the AH-64D Apache Block III.

The army has not clarified performance levels a new scout helicopter would have to meet, but one criterion is clear - the army has already budgeted to spend $1.3 billion to upgrade the avionics of its existing OH-58D fleet. Thus, to spend more to buy a new helicopter, the army must decide to spend less on something else, Crosby said.

Source: Flight International