A crowd watches the maiden flight of the CSeries in Mirabel, Quebec. (Photo: Bombardier)

MonTREAL — Bombardier Inc. says that its new CSeries jetliners will need additional testing and the first planes wont go into service until next year — several months later than previously expected.

The Montreal-based company now says it expects the CS100 will go into service in the second half of 2015.

It says the larger CS300 model will go into service about six months after that.

The initial CSeries planes were expected to be ready for service late this year or early in 2015 after 12 months of flight tests, which began in mid-September last year.

Bombardier says the planes initial performance has been in line with its expectations but the company has decided to take more time to ensure it has what it calls overall system maturity.

The latest delay was announced shortly after Bombardier Aerospace signed a major deal with a new Saudi airline, which has placed firm orders for 16 CS300s, with an option for an additional 10 aircraft.

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The deal is valued at about US$1.21 billion before options, or up to US$1.99 billion if all options are exercised.

The aircraft will be operated by SaudiGulf Airlines, a newly launched national carrier from the Kingdom of Saudi Arabia.

We are thrilled that SaudiGulf Airlines, based in the largest Arab economy — and one with an underserved air travel market — will base the core of its business plan on the CSeries aircraft, said Bombardier Commercial Aircraft president Mike Arcamone.