OTTAWA - The fed's promise to present re-worked F-35 fighter jet cost estimates to Parliament may not be fulfilled until mid-winter now.

The Treasury Board re-tendered a contract offer this week for an auditing firm to go over updated "acquisition and sustainment project assumptions" for the plane.

Under the new tender, the contract would last until Jan. 31, 2013, but a spokeswoman for Public Works Minister Rona Ambrose won't say if that means the government won't meet its already delayed goal of tabling new cost estimates in the fall.

"They're doing everything they can to get it done right and in a timely manner," said Amber Irwin on Friday.

Irwin says the contract was re-tendered to allow accounting firms to sub-contract work, which wasn't allowed in the original call for proposals issues in June.

The push for more solid F-35 cost numbers comes in response to Auditor General Michael Ferguson's report in April that concluded bureaucrats and the government had underestimated costs.

Since April, the Conservatives have appointed a former auditor general, Denis Desautels, to the new secretariat who has taken over the program to replace Canada's old CF-18 fighters.

Meantime, the F-35 has hit a new testing milestone.

A pilot flying a short takeoff and vertical landing version of the plane - slightly different than the model Canada would buy - successfully dropped an inert bomb on Wednesday over the Atlantic Ocean.

American military officials call that "a significant entry into a new phase of testing for the F-35 program."

- with files from Reuters