China's ARJ21 regional jet aircraft has achieved a new milestone in its flight test programme and the aircraft's engine-maker is on track to deliver the first production engine in the fourth quarter.

A senior source at Commercial Aircraft Corporation of China (Comac) says the ARJ21-700 has completed around 540 flight hours as part of its flight test programme.

There are four ARJ21-700s in the flight test programme and all are powered by the GE CF34-10A engine.

GE general manager for the CF34 turbofan programme, Chuck Nugent, says the engine-maker has also delivered spare engines to Comac and produced three -10A engines for GE's own ground test programme that was carried out in the US and totalled 750hr of testing.

"We have validated all the changes to the -10A via ground testing and the additional testing will be done as part of the ARJ21 flight test programme," he says.

"The engine certification is nearing completion and we expect to receive certification in the next month or two," he says, referring to US FAR 33 certification.

This will be followed by Chinese CAR 25 certification, he adds.

The first production engine is due to be delivered to Comac in the fourth quarter, says Nugent.

GE's -10A engine has been performing well in the flight tests because the CF34 is already a proven engine, says Nugent.

"The CF34-10A is a derivative of the CF34-10E engine used on the Embraer 190/195 and essentially the turbofan engine is nearly identical although we made some changes to support the ARJ21's fuselage-mounted application and we made some minor improvements."

GE's -10E engine is mounted under the Embraer regional jet's wing, whereas the -10A engines are mounted towards the rear of the ARJ21 fuselage.

"We designed a completely new nacelle, driven by the fuselage mounted configuration, and there were some slight aerodynamic improvements achieved with the nacelle."

"We also redesigned some structural components for the fuselage mounting, so we looked to reduce weight."

He also says: "We've been implementing fuel reduction improvements to the -10E and -10A."

Nugent adds, that GE is in the process of introducing a new fan blade for the -10E and -10A that promises to deliver "a slight improvement" in fuel burn.

Flight tests have mostly been taking place at China's National Flight Test Centre in Xian but there have also been cold weather flight tests in China's Inner Mongolia province.

The ARJ21-700 is a 90-seat regional jet aircraft designed for 'hot and high' flying conditions. China's government, which is bankrolling the programme, has said it wants the aircraft for new regional routes in remote parts of western China, an area synonymous with mountainous and hot terrain.

Comac was planning to receive Chinese certification in time for first customer delivery in this year's fourth quarter, but the general consensus among industry sources in China is that first delivery is now likely to be in 2011's first quarter.

Source: Air Transport Intelligence news