OTTAWA - The manufacturer of the F-35 has been quietly trying to counter Canadian critics of its oft-maligned stealth fighter.

Over the last few days, senior company officials have held wide-ranging briefings on the troubled program, which has become a political lightning rod for the Harper government.

Lockheed Martin, the world's largest defence contractor, now is trying to rebut the many criticisms of the program, including claims about sticker price and lifetime costs.

The aerospace giant faces the possibility the federal government later this year could take the project to replace the air force's CF-18s out to public tender.

An independent committee at Public Works, struck in the aftermath of last spring's scathing auditor general's report, is examining what other aircraft are in the market, what they can do and what they cost.

While Lockheed Martin F-35 vice-president Stephen O'Bryan says the firm has co-operated with and supports Canada, he laid out a business case for proceeding with program, which estimates say could cost taxpayers nearly $45 billion over its lifetime.

The cost per aircraft is expected to be US$67 million by the time Canada makes the bulk of aircraft purchases, he said.

O'Bryan also predicted that despite conflicting cost estimates between Canada's auditor general and the parliamentary budget officer, the multi-role fighter will be affordable to maintain and sustain.

"I read in places that the cost is increasing, dramatically increasing," O'Bryan said. "The truth of the matter is the F-35 cost is dramatically decreasing. From the first year of production to the fifth year of production we have reduced the cost by over 50 per cent. Every single year, we have reduced the cost of the aircraft."

Critics of the program have complained that software development is far behind schedule. Unlike most aircraft today, the F-35 is highly automated and runs on 9.4 million lines of software code.

But in a presentation Friday, O'Bryan said 85 per cent of that total is already at the in-flight test stage.

"We're doing well on flight tests ... and we're basically on plan," he said Friday on a conference call.

There have been questions about whether Canada needs a stealth fighter, which can defeat a sophisticated enemy's air defences on the first day of a war.

Billie Flynn, a former Canadian air force pilot and now working as a Lockheed Martin test pilot, said stealth is not just for Day 1, and the high-tech onboard sensors make the aircraft more a "battle space commander" supporting other military units.

The upbeat assessment is in contrast to a recent U.S. Defense Department report, which pointed out concerns with the oxygen gauge in the fuel tank and warned an explosion was possible in the event of a lightning strike.

That prompted officials to restrict the F-35 from flying within 40 kilometres of a thunderstorm.

The Pentagon's 2012 Operational Test and Evaluation report also noted that until November of last year, the test team had been unable to execute 30 per cent of baseline operational tests.

There were "operational limitations" and "deficiencies in the air-to-air refuelling systems."

There had been a suggestion in a Canadian government report late last year that Canadian F-35s would not have an air-to-air fuelling system that matched the air force's current tanker fleet.

But O'Bryan said Lockheed Martin has set aside design space to install a separate system for Canada.

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  • An F-35 in final assembly. (Photo: Lockheed Martin)

  • An F-35 ready to take off on a test flight. (Photo: Lockheed Martin)

  • The assembly line has nearly a dozen aircraft at any one time. (Photo: Lockheed Martin)

  • Flight simulators allow pilots to ease into flying the F-35. (Photo: Lockheed Martin)

  • Carts like this are necessary to get around the enormous factory floor. (Photo: Lockheed Martin)

  • More flight testing takes place in the hangars. (Photo: Lockheed Martin)

  • Lockheed-Martin vice-president Steve O'Bryan talks about the testing process. (Photo: Lockheed Martin)

  • Two F-35s flying in tandem during a test flight. (Photo: Lockheed Martin)

  • Chief operations officer Chris Kubasik at a press conference in Washington. (Photo: Nicolas Laffont)