A Canadian aerospace company, is facing damaging import duties on one of their jets has a trade dispute in the United States.
The British government had the suspicion, that Bombardier would lose, and the unions feared sales and UK jobs to the C-would the series be affected.
But a surprise ruling by the US International Trade Commission (ITC) dismissed the action brought by Boeing.
PM Theresa May welcomed the move, calling it “good news” for the British industry.
“The Bombardier and his innovative work forces play an important role in the Northern Irish economy,” she said.
The ITC voted 4-0 in favor of Bombardier.Bombardier ruling Q&A
She decided that it was to protect no injury to U.S. manufacturers, effectively the US Commerce Department, forcing it to reverse course, developed in retaliation against measures to Boeing.
The rates of 292% now orders of C-series-aircraft-American airlines will be imposed.
Over 50 companies in the UK-supply Bombardier with parts for the C-series.
Thousands of jobs in Belfast, where the wings for the aircraft are made, depends on its success.Analysis
By the news broadcast of the BBC NI Business correspondent Julian O’neill
This was an unexpected result – the British and Canadian governments had to predict a home win for Boeing.
It is a decision that you should raise no immediate threat to the jobs at Bombardier in Belfast.
About 50 of the smaller British companies to supply parts for the C-series will also breathe a sigh of relief.
Instead of looking at potential sales lost, Bombardier and its workforce have reason for fresh optimism.
A spokesman for Bombardier said the ITC decision was “a victory for innovation, competition and the rule of law.”
“The C-series is the innovative and efficient new aircraft in a generation.,” She said.
“The development and production represent thousands of jobs in the United States, Canada, and the United Kingdom.”
A spokesman for Boeing said it was “disappointed” the ITC decision and that it will “review the detailed conclusions, if they are released”.
Steve Turner, Unite assistant general secretary, said it was “the right decision”.
He said Bombardier employees in Northern Ireland and throughout the supply chain in the UK “are breathing a huge sigh of relief”.
Business-Secretary of state Greg Clark said it was “good news for the employees in Northern Ireland and the supply chain in the UK, which has a great future ahead”.
“The decision of the International Trade Commission confirms what the British and Canadian governments to work hand-in-hand, has maintained from the beginning that it is justified in this case. We are pleased that the ITC have now detected,” he said.