UPDATE 6-Pentagon tries again on aerial tanker contest

* Pentagon aims for June 2010 contract award

* Follows two botched efforts to buy tankers

* Seeks to make requirements clear, unbiased

* Some lawmakers say WTO trade dispute should be a factor (Recasts first paragraph; adds quotes from Pentagon, Air Force officials)

By Jim Wolf and Andrea Shalal-Esa

WASHINGTON, Sept 24 (Reuters) - The Pentagon spelled out on Thursday how it would judge a politically sensitive, $35-billion competition for new refueling planes after two failed attempts to award a contract.

Boeing Co (BA.N), the Pentagon's No. 2 supplier by sales, is vying for the deal against a team made up of Northrop Grumman (NOC.N) and Europe's EADS (EAD.PA), parent of Airbus.

The contract would be for an initial 179 tankers, the first of three batches to be bought over coming decades at a projected cost of $100 billion or more.

The Pentagon said it would release draft bidding rules on Friday and give the companies 60 days to comment on them before final specifications are released.

It plans to award a contract by June for the first new planes to be delivered in 2015 and operational in 2017.

This is the Pentagon's third attempt in eight years to start replacing its KC-135 tankers, which average more than 50 years old.

A year ago, it scrapped a contract awarded to Northrop and EADS after the Government Accountability Office, the audit arm of Congress, upheld a protest by Boeing. GAO found the Air Force had not followed its own rules in evaluating the bids.

"This time we will be crystal clear about what we want and what the bidders need to do to win," Deputy Defense Secretary William Lynn said in a series of briefings, first to lawmakers, then to reporters.

"We have crafted this approach to favor no one except the warfighter and taxpayer," he said. The competition would involve price, long-term ownership costs and aircraft performance. [ID:nN24469923]

TRADE FIGHT EXCLUDED

The Pentagon exempted from the evaluation a Boeing-Airbus fight at the World Trade Organization over what each claimed was the others' illegal aircraft subsidies.