Bombardier has won a trade case in the United States, overturning a decision to impose damaging tariffs on imports of its C-Series aircraft.
The UK government had suspected that the aerospace and transportation company would lose. Unions had feared sales and UK jobs would be hit.
But in a surprise ruling, the US International Trade Commission (ITC) rejected a complaint brought by Boeing.
The ITC voted 4-0 in favour of Bombardier.
It means tariffs of 292% will not now be imposed on orders of C-Series planes by American carriers.
About 50 companies in the UK supply Bombardier with parts for the C-Series.
One thousand jobs in Belfast, where the wings for the plane are made, depend on its success.
A spokesperson for Bombardier said the ITC’s decision was “a victory for innovation, competition and the rule of law.”
“The C-Series is the most innovative and efficient new aircraft in a generation.,” they said.
“Its development and production represent thousands of jobs in the United States, Canada, and the United Kingdom.”
A spokesperson for Boeing said it was “disappointed” by the ITC’s decision and that it would “review the detailed conclusions when they are released”.