The Comac ARJ-21 regional jet, which can seat up to 90 passengers, received the Civil Aviation Administration of China (CAAC) type certification last December and will be delivered to launch customer Chengdu Airlines shortly, two people familiar with the plane's programme told Reuters.

The plane will fly without U.S. Federal Aviation Administration (FAA) certification despite a five-year effort to have the FAA endorse CAAC's certification procedures, the people said.

An FAA type certificate would have boosted the reputation of the airplane's developer Commercial Aircraft Corp of China (Comac) and cleared the way for the plane to be sold and operated globally - though expectations for foreign sales had been low. Without it, the aircraft can operate only in China and some Asian, African and South American countries that recognise the CAAC's certificate.

Chengdu Airlines, a low-cost carrier, is expected to fly the plane on commercial domestic operations in the first quarter of 2016. Comac has received nearly 350 orders for the ARJ-21, mainly from Chinese airlines and leasing firms.

SHADOWING

Since 2010, the FAA has undertaken a shadow certification process to assess the CAAC's ability to conduct a technical assessment of aircraft. But tensions arose between the two regulators last year over various technical and bureaucratic issues, before the process ended in early 2015, those familiar with the programme said.

People close to Comac believe the FAA also was dragging its feet in part because of bilateral political and economic considerations. "While the CAAC wanted to learn from the FAA, they felt the Americans were too rigid and unnecessarily delaying things. And the longer the delay, the greater the embarrassment to the Chinese," said one of those individuals.

However, a CAAC official responsible for certification and people close to the FAA stressed that the two regulators were still working to resolve outstanding issues as a "top priority".

In an emailed response to Reuters for this article, the FAA said the ARJ-21 was never intended to be certificated by the FAA under the shadow evaluation process, and Comac planned a derivative model of the plane to comply with FAA standards.

"The FAA enjoys a good working relationship with CAAC and we continue to work together to develop a path to work towards certification of the derivative model of the ARJ-21 and, possibly, the C919," the FAA said referring to a narrow-body jet China is developing to compete with the Airbus A320 and Boeing 737 models.

Also, the FAA said it could certify an airplane after it enters service if it can be shown to comply with all relevant airworthiness and manufacturing standards.

AVIATION COOPERATION

Putting the ARJ-21 into service without FAA certification would be a setback to U.S. and China aviation cooperation, arguably one of the outstanding achievements since the two governments re-established diplomatic relations in 1979.

Chinese airlines have bought hundreds of Boeing jets as the country's aviation sector opened up and boomed, and Boeing plans to open a completions and delivery centre in China for its 737 aircraft, its first plant outside the United States.

U.S. aerospace firms have also invested heavily in China, and companies such as General Electric, Rockwell Collins, Honeywell and United Technologies are suppliers for the ARJ-21 and C919 jet.

"It could be seen as a loss of face for the Chinese given they deem FAA certification a key rite of passage for what will be the first domestically built jet to enter commercial service," said Greg Waldron, Asia managing editor at Flightglobal, an industry news and data service.

Comac could eventually ask the European Aviation Safety Agency (EASA) to certify the ARJ-21 once it has been delivered, and ask it to help with the C919 as well, the people familiar with the programme said.

"Given the effort and prestige China is pouring into the C919, getting FAA or EASA certification is a definite requirement both for the image of the programme and the ambition to garner foreign sales," said Waldron.

"We don’t know if and when the Chinese authority will apply to us for a certification," an EASA spokesman said.

"LEARNING EXPERIENCE"

China has been working for 40 years to produce and deliver a homegrown commercial airliner.

It first developed the Y-10, a four-engined jet, in the 1970s but never delivered it to customers. It has exported some MA-60 turboprop planes, a civil version of the license-produced Soviet-designed Antonov AN-24 military transport.

Comac plans to eventually upgrade the ARJ-21 so it's closer in performance to regional jets made by Embraer, Mitsubishi Aircraft and Bombardier.

The current version of the ARJ-21 and the programme itself is a "learning experience," said Richard Aboulafia, aerospace analyst at the Teal Group. "Any airline forced to operate this jet will be at a severe competitive disadvantage against any airline with a modern aircraft."

That means China's hopes may rest on the C919.

Comac aims to complete its flight test and certification programme in less than half the time it took with the ARJ-21, say those familiar with the company's plans.

"It has engaged foreign suppliers experienced in global aircraft programmes with Airbus and Boeing much earlier, and they're far more involved in the C919," said one of those familiar with the programme.

"FAA or EASA certification would legitimise the programme and create interesting new opportunities for China’s aerospace sector. Such certification would be a watershed development," added Waldron at Flightglobal.

(Reporting by Siva Govindasamy and Matthew Miller, with additional reporting by Fang Yan in BEIJING, David Morgan in WASHINGTON and Tim Hepher in PARIS; Editing by Ian Geoghegan)

By Siva Govindasamy and Matthew Miller