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.

谷歌譯文：

北京/巴黎（路透社）-十幾名熟悉該計劃的人士告訴路透社，中國的C919單通道飛機的開發已經比原定計劃落後了至少五年，進度比預期的要慢。 ）遇到一系列技術問題，這些問題嚴重限制了試飛。

文件照片：中國國產C919客機的第五架原型機將於2019年10月24日從中國上海浦東國際機場起飛，進行首次試飛.REUTERS / Stringer / File Photo

在複雜的航空項目中，延誤是很常見的，但是進展特別緩慢的是中國的潛在尷尬。中國已經做出了巨大的努力，這是其首次重大嘗試來打破波音和空中客車在全球噴氣機市場的控制。

據四位了解此事的人士稱，最近的問題歸結為數學錯誤。

四位知情人士告訴路透社，COMAC工程師錯誤地計算了飛機飛行中的雙引擎所承受的力（在業界稱為載荷），並向引擎製造商CFM International發送了不準確的數據。知情人士說，結果是，發動機及其外殼可能都必須進行加固，這很可能要以中國商飛的費用為代價-儘管另一位消息人士否認了任何修改。

這種以及其他技術和結構上的故障意味着到12月初，經過超過兩年半的飛行測試，中國商飛完成了尚需民航局最終批準的4,200小時空中飛行的不到五分之一中國（CAAC）的一位知情人士告訴路透社。

自2008年以來一直在秘密開發C919的中國商飛很少披露其目標。公司官員楊揚在9月份對中國官方媒體說，他希望在兩到三年內獲得中國監管機構的認證，而不會提供更多細節。該公司先前公開宣布的目標是2020年底。中國商飛的其他官員表示，他們的目標是在2021年進行認證和交付。

中國商飛沒有回應路透社對此事發表評論的要求。通用電氣與法國賽峰集團的合資企業CFM拒絕置評。

其中一位消息人士告訴路透社，中國商飛尚未確定要發送給發動機製造商的正確計算和數據，這對於確保發動機在重負荷下不會發生故障至關重要。另一位表示，負荷計算通常在開發過程中發展。

但知情人士告訴路透社，但鑑於不確定性，無法保證中國商飛將達到楊的2021-2022目標。

一位熟悉發動機問題的消息人士告訴路透社：“事情並非總能按計划進行，但我希望中國商飛會放慢腳步，並儘量不要着急。” “否則以後會出現很多問題。”

時間壓力

引擎計算錯誤並不能反映出缺乏理論上的理解-近二十年來，中國一直將人們帶入太空。但這確實說明了美國國家航空製造商缺乏設計和製造商用飛機的經驗。

問題不僅限於繪圖板。兩名消息人士稱，中國商飛在最初製造的幾架飛機的水平穩定器中發現了裂縫，儘管該問題現已得到解決。三位消息人士告訴路透社，它還發現連接到發動機的變速箱很容易破裂，從而導致發動機在試飛過程中停機，這個問題可能會影響目前正在試飛的所有六架C919飛機。

他們說，對齒輪箱進行定期檢查以檢查是否破裂和漏油已限制了中國商飛的飛行測試計劃。

兩名消息人士告訴路透社，變速箱問題是在2018年發現的，此前未曾報道過，原因是意外振動。消息人士稱，該計劃的工程師已經找到了將風險最小化的方法。

不必要的振動，甚至在歷史悠久的航空航天製造商中也面臨着問題，在最壞的情況下，振動會粉碎發動機內部的零件。據路透社10月報道，由於某些新發動機的破壞性振動，美國發動機製造商普惠公司（Pratt＆Whitney）修改了軟件。

幻燈片放映（2張圖片）

然而，問題的累積使中國商飛明顯落後於計劃，這可能會造成高昂的代價。

C919旨在與波音737 MAX和空中客車320neo系列競爭。在波音和空中客車達成交易以接管巴西航空工業公司和龐巴迪公司生產的競爭對手飛機之後，中國的中國商飛現在實際上是市場上擁有100個座位的飛機的第三選擇。

大多數行業預測員現在預計，由於地緣政治緊張局勢導致商業信心減弱，對商用飛機的長期周期性需求需求今年將消退，這意味着在2021年或2022年首飛的飛機很可能會錯過未來幾年的訂單。

中國商飛知道時間壓力。消息人士告訴路透社，其六架試飛C919中的最後三架在塗裝工作完成之前就已進行了首次飛行。

高水平

北京將C919納入了“中國製造2025”計劃的組成部分，該計劃旨在趕上先進技術並幫助該國實現自給自足。

這項努力引起了美國聯邦檢察官的注意，他們於2018年指控一群中國情報人員，黑客和公司內部人員闖入全球13家航空航天製造商的網絡，其中包括一家描述與CFM相匹配的公司，以竊取可能有助於中國建造噴氣發動機的敏感數據。中國否認參與黑客活動。

一些分析人士說，如果C919飛機未能立即在國際市場上競爭，北京可能不會完全失望，因為中國政府可以指示自己的航空公司購買這架飛機。

中國商船公司表示已收到C919的815個臨時訂單，其中絕大多數是中國國有承運人和租賃公司。迄今為止，唯一的海外買家是通用電氣旗下的租賃公司GECAS。幾乎沒有定單。

DCA Chine-Analyse首席分析師Jean-FrançoisDufour表示：“ C919的真正使命是征服由其兩個外國競爭對手主導的國內市場。” “從現在起的10到15年內，下一代C919或中國商飛公司開發的其他型號可能會成為全球舞台上的真正競爭對手。”

邱志遠在北京和蒂姆·赫弗在巴黎的報道； Brenda Goh在上海和Jamie Freed在悉尼的補充報道； Bill Rigby編輯

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