WARWICK — Two state legislators are blasting the Rhode Island Airport Corporation for not providing detailed financial plans about its proposed T.F. Green expansion project, a proposal they say may be too ambitious given the state’s economic climate.

In a letter last week to the chairman of the corporation board, Warwick Representatives Joseph M. McNamara and Eileen S. Naughton criticized the agency for not keeping the Federal Aviation Administration and the Rhode Island public better informed about their spending plans for the proposed longer runway.

Their frustrations come on the heels of an FAA letter last month to the Airport Corporation saying it will contribute only $150 million to the runway extension project at Green, despite estimates that project costs could total more than $500 million. That letter also raised questions of whether the runway plans have grown too costly and possibly overreaching, given the transportation needs of passengers at T.F. Green.

The FAA’s contribution would leave the Airport Corporation, an independent state agency, responsible for a bill of $350 million or more if it wants to implement expansion plans. The agency says it may eventually float bonds to pay its share.

McNamara yesterday called both the funding plan and the price tag “shocking” given the statewide budget shortfall.

“My question and major, major concern is the [projected $450 million] debt that we already have and for a public agency — because that’s what they are, they are under the division of economic development — to project a plan in which there is almost $400 million in deficit funding … without a specific financial plan is unrealistic and disappointing,” he said in an interview.

The Airport Corporation shot back yesterday with a now familiar retort: it’s too early in the process to draw up detailed financial elements The agency hasn’t yet settled on a runway expansion plan, meaning it hasn’t yet determined the length and direction of the proposed extension or the associated project costs.

Airport officials noted that since the FAA letter was written, the two agencies have met and are working closely to determine what kind of financial workup the FAA wants to see.

“We expect to get a financial plan in the next couple days,” said FAA regional spokesman Jim Peters.

But Brian C. Schattle, the Airport Corporation’s chief financial officer, indicated that no formal document yet exists.

“Whether or not a financial plan gets put together or how it will be finalized we will be working on that,” Schattle said. Airport Corporation officials are scheduled to meet with the FAA next week, he said.

Regardless of the status of communication between the two agencies, McNamara calls the airport corporation’s lack of financial planning unacceptable given the state’s estimated $450 million deficit.

While the City of Warwick’s fierce opposition to T.F. Green expansion thus far has been unable to derail the corporation’s plans, dissent on Smith Hill could pose a problem for the project.

In an interview last month, Airport Corporation CEO Mark Brewer (who will step down as CEO today to run the Manchester-Boston Regional Airport, in New Hampshire) said the corporation will plan on looking at other funding sources including floating bonds or increasing passenger facility charges once it selects a preferred expansion alternative, next year.

If it does choose to float bonds, it will need approval from the General Assembly, which must sign off on bonding for any state agency, including the Airport Corporation.

That fact is not lost on McNamara, who says he plans to tell his House colleagues the same thing he told the Airport Corporation: “That these projects are based on false assumptions and ignore current trends in the industry and for those reasons I personally as one individual and one representative from the area would testify against it … and I would encourage my colleagues to do the same.”

If the corporation does choose to borrow for the project, Schattle noted yesterday, revenue bonds, rather than general-obligation bonds, would be issued, meaning the agency would be solely responsible for paying them off.

Naughton did not return a call for comment yesterday. And corporation spokeswoman Patti Goldstein said the board chairwoman, Dr. Kathleen C. Hittner, was not available.

cneedham@projo.com