RIGA/MONTREAL (Reuters) - Canada's Bombardier (>> Bombardier, Inc.) is tackling a complex paper trail for regulators as it draws close to approval for its CSeries jet, while pursuing a global offensive to boost flagging sales.

Executives in Europe to showcase the jet to buyers including Latvia's AirBaltic said safety certification would be completed this year as planned.

Documenting software is an increasingly challenging step in certifying high-tech modern jets, and one that can cause last-minute delays, especially when outside suppliers are involved.

"There are 18,000 certification documents that we had to do and we are down to a few hundred," Dewar said.

"There is a formal approval process that is very rigorous, but I am not whatsoever concerned about doing certification this year," he said, adding the risk of delays in the schedule had eased with the recent completion of flight testing.

Industry sources say software documentation, maintenance details and releasing the flight manual are the tasks left before the plane can be cleared for service.

Following two years of delays and doubts over the Canadian company's ability to complete CSeries development, Bombardier is on a sales offensive, having won a cash injection from Quebec and brought the aircraft close to certification.

One of the perceived risks has been "whether we would have enough liquidity to get us through, and since the recent announcements that is behind us," said program head Rob Dewar.

"Through a combination of those things we have seen increased customer engagement and even North American customers are heavily engaged, whereas before they were waiting and seeing. That has changed," he told Reuters.

Bombardier is trying to win orders from United Airlines (>> United Continental Holdings Inc) and JetBlue (>> JetBlue Airways Corporation) but faces competition from Embraer (>> Embraer SA) as well as giants such as Airbus, which is trying to persuade JetBlue to take larger A321s, industry sources say.

After a 14-month dearth of orders, Bombardier aims to boost the number of firm purchases from 243 to 300 by the time the 110-130-seater enters service in first-half 2016.

"We are confident of being able to achieve the numbers we have stated and capture orders in the months ahead," said Ryan DeBrusk, sales vice president for Europe.

"There are a number of large carriers here in Europe where discussions are quite strong," he said.

Addressing another priority area, Dewar said engine maker Pratt & Whitney (>> United Technologies Corporation) was doing "very well" in ramping up production and its engine was now "exactly" on specification.

(Additional reporting by Gederts Gelzis; editing by Andrew Roche)

By Tim Hepher and Allison Lampert