FOR five decades Boeing Co has awarded bigger and bigger shares of its supply contracts to Japanese firms, but that could change after Japan Airlines' shock defection to Airbus and as the planemaker seeks to win orders in China.
Boeing's carbon composite 787 is 35 per cent made in Japan - as big a share as it builds in-house - but Japanese aviation insiders fear the Dreamliner could be the high water mark of the industry's partnership with the United States company.
The close cooperation has not only benefited Japan's industrial giants Mitsubishi Heavy Industries, Kawasaki Heavy Industries and Fuji Heavy Industries - it has also enabled Boeing to dominate one of the world's biggest aviation markets with a share of more than 80 per cent.
That status quo crumbled on Monday, when JAL signed a deal to buy 31 Airbus A350s, its first purchase of European jets.
In rejecting the rival Boeing 777X, JAL can only have increased the likelihood that the US company's next project will be less Japanese.
"Negotiations for the 777X work share are ongoing, and that may be influenced by the JAL decision," said a government official who helps oversee Japan's aerospace industry.
The fear in Japan is that Boeing, which says the business it gives Japan adds up to 22,000 jobs accounting for around 40 per cent of the nation's aerospace workforce, may be tempted to shift more production to China, South Korea or elsewhere.
"If I was Boeing, I would hold their feet to the fire," said Lance Gatling, founder of aerospace and defence consultancy Nexial Research here. "International competition for what they build can only increase."
JAL's defection to Airbus stacks on top of other reasons why the Japanese may find it harder to win bigger chunks of business from their American partner.
Boeing has said it will take a more conventional approach to the 777X, a re-engined more fuel efficient upgrade of its long-range, wide-body 777.
That, industry watchers say, could mean it builds the aircraft wings at home, after allowing the Dreamliner wings to be made overseas - in Japan - for the first time.
A longer-term worry for the Japanese is that their country, once Asia's biggest aircraft market, is no longer the goldmine that first drew Boeing to seek panel suppliers for its 747 there.
Both Boeing and European rival Airbus are now more focused on vying for business in burgeoning China. The entry price often imposed by the Chinese government is a share of the build.
One lure that could keep Boeing heavily involved in Japan is government financial support for R&D that could end up in its jets.
According to the European Union, which is locked in an aircraft subsidy dispute with the US, Boeing benefits from support from the Japanese government for development of the 787, including financing of up to 70 per cent of development costs incurred by Japanese suppliers. Reuters