BEIJING/PARIS (Reuters) - Development of China’s C919 single-aisle plane, already at least five years behind schedule, is going slower than expected, a dozen people familiar with the program told Reuters, as the state-owned Commercial Aircraft Corporation (COMAC) struggles with a range of technical issues that have severely restricted test flights.

Delays are common in complex aerospace programs, but the especially slow progress is a potential embarrassment for China, which has invested heavily in its first serious attempt to break the hold of Boeing and Airbus on the global jet market.

The most recent problem came down to a mathematical error, according to four people with knowledge of the matter.

COMAC engineers miscalculated the forces that would be placed on the plane’s twin engines in flight - known in the industry as loads - and sent inaccurate data to the engine manufacturer, CFM International, four people familiar with the matter told Reuters. As a result, the engine and its housing may both have to be reinforced, the people said, most likely at COMAC’s expense – though another source denied any modification.

That and other technical and structural glitches meant that by early December, after more than two and a half years of flight testing, COMAC had completed less than a fifth of the 4,200 hours in the air that it needs for final approval by the Civil Aviation Administration of China (CAAC), two people close to the project told Reuters.

COMAC, which has been developing the C919 largely in secret since 2008, rarely discloses its targets. Company official Yang Yang told Chinese state media in September that he expected certification by the country’s regulators in two to three years, without giving any further details. The company’s previous publicly stated target was end-2020. Other COMAC officials have said they are aiming for certification and delivery in 2021.

COMAC did not respond to Reuters requests for comment for this story. CFM, a joint venture between General Electric and France’s Safran, declined comment.

COMAC has still not finalised the correct calculations and data to send to the engine manufacturer, which are key to ensuring that the engine does not fail under heavy loads, one of the sources told Reuters. Another said load calculations often evolve during development.

But given the uncertainty, there is no guarantee COMAC will meet Yang’s 2021-2022 target, people close to the program told Reuters.

“Things do not always work out as planned, but I hope COMAC would slow down a bit and try not to rush things,” one of the sources familiar with the engine issue told Reuters. “Otherwise there will be tons of issues later on.”

TIME PRESSURE

The engine miscalculation does not reflect a lack of theoretical understanding - China has been putting people in space for almost two decades. But it does illustrate the national aerospace manufacturer’s lack of experience in designing and building commercial aircraft.

Problems have not been confined to the drawing board. COMAC found cracks in the horizontal stabilizers of some of the first few aircraft built, two sources said, although that problem has now been fixed. It also found a gearbox attached to the engine was vulnerable to cracking, which caused an engine to shut down during a test flight, three sources told Reuters, a problem that potentially affects all six C919 jets now in test flights.

Regular inspections of the gearbox to check for cracks and leaking oil have curtailed COMAC’s flight test program, they said.

The gearbox problem, discovered in 2018 and not previously reported, was due to unexpected vibrations, two sources told Reuters. Engineers on the program have found ways to minimize the risks, the sources said.

Unwanted vibration, which in the worst case can shred parts inside an engine, is a problem faced by even long-established aerospace manufacturers. U.S. engine maker Pratt & Whitney revised software due to destructive vibration on some new engines, Reuters reported in October.

However, the accumulation of problems has put COMAC significantly behind schedule, which could prove costly.

The C919 is designed to compete with the Boeing 737 MAX and Airbus 320neo families. After Boeing and Airbus struck deals to take over production of rival planes made by Embraer and Bombardier, China’s COMAC is now effectively the third option in the market for planes with more than 100 seats.

Most industry forecasters now expect the prolonged cyclical boom in demand for commercial planes to fade this year, as business confidence wanes amid geopolitical tensions, meaning a plane that debuts in 2021 or 2022 will likely miss out on orders for years to come.

COMAC is aware of the time pressure. The last three of its six test flight C919s were put into the air for their first flight before the paint job had been completed, sources told Reuters.

HIGH STAKES

Beijing made the C919 an integral part of its ‘Made in China 2025’ initiative, designed to catch up on sophisticated technologies and help the country become self-sufficient.

The effort has attracted the attention of U.S. federal prosecutors, who in 2018 charged a group of Chinese intelligence officers, hackers and company insiders with breaking into the networks of 13 aerospace manufacturers around the world, including a company whose description matches CFM, in order to steal sensitive data that might help China build a jet engine. China has denied any involvement in hacking.

Beijing may not be entirely disappointed if the C919 jet fails to compete immediately in international markets, some analysts say, as the Chinese government can direct its own airlines to buy the jet.

Chinese state-owned carriers and leasing companies account for the vast majority of the 815 provisional orders COMAC says it has received for the C919. The only overseas buyer so far is the leasing company GECAS, owned by General Electric. Few of the orders have been finalized.

“The C919’s real mission is to conquer a domestic market dominated by its two foreign competitors,” said Jean-François Dufour, chief analyst of DCA Chine-Analyse. “Ten to 15 years from now, a next-generation C919, or other models developed by COMAC, may become real competitors on the global scene.”

Reporting by Stella Qiu in Beijing and Tim Hepher in Paris; Additional reporting by Brenda Goh in Shanghai and Jamie Freed in Sydney; Editing by Bill Rigby

Our Standards:The Thomson Reuters Trust Principles.

谷歌译文：

北京/巴黎（路透社）-十几名熟悉该计划的人士告诉路透社，中国的C919单通道飞机的开发已经比原定计划落后了至少五年，进度比预期的要慢。 ）遇到一系列技术问题，这些问题严重限制了试飞。

文件照片：中国国产C919客机的第五架原型机将于2019年10月24日从中国上海浦东国际机场起飞，进行首次试飞.REUTERS / Stringer / File Photo

在复杂的航空项目中，延误是很常见的，但是进展特别缓慢的是中国的潜在尴尬。中国已经做出了巨大的努力，这是其首次重大尝试来打破波音和空中客车在全球喷气机市场的控制。

据四位了解此事的人士称，最近的问题归结为数学错误。

四位知情人士告诉路透社，COMAC工程师错误地计算了飞机飞行中的双引擎所承受的力（在业界称为载荷），并向引擎制造商CFM International发送了不准确的数据。知情人士说，结果是，发动机及其外壳可能都必须进行加固，这很可能要以中国商飞的费用为代价-尽管另一位消息人士否认了任何修改。

这种以及其他技术和结构上的故障意味着到12月初，经过超过两年半的飞行测试，中国商飞完成了尚需民航局最终批准的4,200小时空中飞行的不到五分之一中国（CAAC）的一位知情人士告诉路透社。

自2008年以来一直在秘密开发C919的中国商飞很少披露其目标。公司官员杨扬在9月份对中国官方媒体说，他希望在两到三年内获得中国监管机构的认证，而不会提供更多细节。该公司先前公开宣布的目标是2020年底。中国商飞的其他官员表示，他们的目标是在2021年进行认证和交付。

中国商飞没有回应路透社对此事发表评论的要求。通用电气与法国赛峰集团的合资企业CFM拒绝置评。

其中一位消息人士告诉路透社，中国商飞尚未确定要发送给发动机制造商的正确计算和数据，这对于确保发动机在重负荷下不会发生故障至关重要。另一位表示，负荷计算通常在开发过程中发展。

但知情人士告诉路透社，但鉴于不确定性，无法保证中国商飞将达到杨的2021-2022目标。

一位熟悉发动机问题的消息人士告诉路透社：“事情并非总能按计划进行，但我希望中国商飞会放慢脚步，并尽量不要着急。” “否则以后会出现很多问题。”

时间压力

引擎计算错误并不能反映出缺乏理论上的理解-近二十年来，中国一直将人们带入太空。但这确实说明了美国国家航空制造商缺乏设计和制造商用飞机的经验。

问题不仅限于绘图板。两名消息人士称，中国商飞在最初制造的几架飞机的水平稳定器中发现了裂缝，尽管该问题现已得到解决。三位消息人士告诉路透社，它还发现连接到发动机的变速箱很容易破裂，从而导致发动机在试飞过程中停机，这个问题可能会影响目前正在试飞的所有六架C919飞机。

他们说，对齿轮箱进行定期检查以检查是否破裂和漏油已限制了中国商飞的飞行测试计划。

两名消息人士告诉路透社，变速箱问题是在2018年发现的，此前未曾报道过，原因是意外振动。消息人士称，该计划的工程师已经找到了将风险最小化的方法。

不必要的振动，甚至在历史悠久的航空航天制造商中也面临着问题，在最坏的情况下，振动会粉碎发动机内部的零件。据路透社10月报道，由于某些新发动机的破坏性振动，美国发动机制造商普惠公司（Pratt＆Whitney）修改了软件。

幻灯片放映（2张图片）

然而，问题的累积使中国商飞明显落后于计划，这可能会造成高昂的代价。

C919旨在与波音737 MAX和空中客车320neo系列竞争。在波音和空中客车达成交易以接管巴西航空工业公司和庞巴迪公司生产的竞争对手飞机之后，中国的中国商飞现在实际上是市场上拥有100个座位的飞机的第三选择。

大多数行业预测员现在预计，由于地缘政治紧张局势导致商业信心减弱，对商用飞机的长期周期性需求需求今年将消退，这意味着在2021年或2022年首飞的飞机很可能会错过未来几年的订单。

中国商飞知道时间压力。消息人士告诉路透社，其六架试飞C919中的最后三架在涂装工作完成之前就已进行了首次飞行。

高水平

北京将C919纳入了“中国制造2025”计划的组成部分，该计划旨在赶上先进技术并帮助该国实现自给自足。

这项努力引起了美国联邦检察官的注意，他们于2018年指控一群中国情报人员，黑客和公司内部人员闯入全球13家航空航天制造商的网络，其中包括一家描述与CFM相匹配的公司，以窃取可能有助于中国建造喷气发动机的敏感数据。中国否认参与黑客活动。

一些分析人士说，如果C919飞机未能立即在国际市场上竞争，北京可能不会完全失望，因为中国政府可以指示自己的航空公司购买这架飞机。

中国商船公司表示已收到C919的815个临时订单，其中绝大多数是中国国有承运人和租赁公司。迄今为止，唯一的海外买家是通用电气旗下的租赁公司GECAS。几乎没有定单。

DCA Chine-Analyse首席分析师Jean-FrançoisDufour表示：“ C919的真正使命是征服由其两个外国竞争对手主导的国内市场。” “从现在起的10到15年内，下一代C919或中国商飞公司开发的其他型号可能会成为全球舞台上的真正竞争对手。”

邱志远在北京和蒂姆·赫弗在巴黎的报道； Brenda Goh在上海和Jamie Freed在悉尼的补充报道； Bill Rigby编辑

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