OTTAWA - The air force has raised questions about whether enough has been budgeted to train pilots for the F-35 stealth fighters.

About $1.3 billion was set aside for training, simulators and other infrastructure under the Harper government's proposed $9-billion capital purchase of the radar-evading jets.

But documents obtained under the Access to Information Act show air force planners have been concerned about the dollar projection.

That's because it was calculated for the standard Defence Department estimate of 20 years' of flying, rather than the lifetime of the aircraft, which is estimated at 36 years.

The parliamentary budget officer has criticized the government and defence bureaucrats for using the two-decade yardstick to measure F-35 costs when the equipment would remain in service much longer.

The documents suggest taxpayers might have to shell out more training dollars after the 20-year window ends, and they indicate the investment plan comes up "approximately $2 billion short" of the requirement.

"No training option currently affordable," said a July 5, 2010, presentation to the chief of air staff.

"CF/Air Force Investment plan must be rebalanced in order to permit operations and sustainment of 65 (joint strike fighters)."

One of seven scenarios considered assumes all pilot training is conducted at bases in the U.S., with a basic cost of $1.7 billion. Another possibility discussed involved using leased F-35s for training over and above the 65 the air force plans to purchase.

In the end, the military decided to train the initial cadre of pilots at a U.S. Air Force base in Florida, then move training back to Canada within six years, depending on available funding. But the documents noted "there is no (Government of Canada) direction/mandate to maintain a domestic, sovereign pilot conversion and operational training capability."

The Conservatives, including Prime Minister Stephen Harper, have insisted no more than $9 billion will be spent on the acquisition. The issue arose again in the aftermath of the auditor general's scathing April 3 report on the program, which suggested the government low-balled the estimated cost. The Tories responded by freezing project funding.

"The government has clearly communicated the budget that we have to replace Canada's aging CF-18s, and we will stay within that budget," Foreign Affairs Minister John Baird said in the House of Commons.

The government is currently recasting the stealth-fighter numbers in answer to some of Auditor General Michael Ferguson's criticisms, which set off a Parliamentary firestorm. Fallout has included hearings by the House of Commons public accounts committee, which meets Tuesday.

Oversight of the program has been handed to a new F-35 secretariat at Public Works, which could be in line for a name change even before its shingle hung up.

Government sources said there is concern the name leaves the impression the fix is in for the multi-role fighter, even though the government continued to insist in the Commons on Monday that no contract has been signed.

NDP procurement critic Matthew Kellway said the training documents are another example of where the full life-cycle cost has not been fully disclosed.

"What we've had from DND is inaccurate and incomplete costing of these planes," said Kellway. "This is certainly a concern and speaks to the way this entire project has been managed. Pilots and ground crew need training" over the lifetime of the program.

In the Commons, Liberal MP Ralph Goodale demanded that Tuesday's meeting of the public accounts committee be open to the public as MPs draw up a witness list for hearings.

The internal documents, meanwhile, say the air force will need to set aside as many as 17 of its pricey F-35s for training whenever a program is established in Canada.

The air force had originally asked for 80 aircraft in order to meet its operational and training requirements and has repeatedly said 65 is the minimum number it can live with under the circumstances.