BOSTON (AP) — Two powerful congressmen asked the Federal Aviation Administration on Tuesday to answer whether it ruled that a Massachusetts offshore wind project wasn't a danger to airplanes because of political pressure.

In a letter to the FAA's Acting Administrator, U.S. Reps. Darrell Issa and John Mica referred to internal FAA documents, obtained by an opponent of the Cape Wind project, in which FAA employees repeatedly refer to the high-profile politics of the first-in-the-nation project.

One manager wrote in May 2010, "It would be very difficult politically to refuse approval of this project."

Issa and Mica wrote in their letter to Michael Huerta that it would be "most troubling" if politics trumped safety concerns when the FAA ruled on Cape Wind.

The congressmen asked the FAA to provide various documents by July 31, including any communication about Cape Wind over the last 3½ years between the agency, Cape Wind, federal officials and the White House.

It also flatly asked the agency to answer if it was influenced by political considerations, including the U.S. Interior Secretary's 2010 approval of the project and the Obama Administration's desire to promote green energy projects.

"A politically based determination of the Cape Wind project by FAA is an unacceptable use of federal authority," the congressmen wrote. Issa, a California Republican, chairs the Oversight and Government Reform Committee. Mica, a Florida Republican, is chair of Transportation and Infrastructure.

In a statement, the FAA said it "makes obstruction evaluations based on safety considerations and the available solutions to mitigate potential risks."

Cape Wind spokesman Mark Rodgers noted the project has won approvals after review by both Republican and Democrat administrations, and that the FAA has also cleared the project on three separate occasions in the last decade.

The most recent FAA clearance came in May 2010, but that was overturned by an appeals court which said the FAA didn't adequately consider the 130-turbine project's effects on pilots that fly by sight only.

Rodgers said he was hopeful the FAA would again approve the project and added that false charges that politics were boosting Cape Wind are an old tactic of its chief opponent, the Alliance to Protect Nantucket Sound, which obtained the FAA documents through a public records request.

"The only politics being applied to this important clean energy project has been and continues to be on the part of project opponents," he said.

Audra Parker, head the alliance, said proof that the opposite is true keeps mounting. "The fact these particular chairmen are asking questions is more evidence of the pattern of political favoritism for Cape Wind," she said.

Cape Wind, proposed in 2001, hopes to begin construction in 2013 and produce electricity by 2015.

Air traffic concerns about the project center around radar reflections off its spinning 440-foot turbines. The "clutter" makes it difficult for air traffic controllers to spot planes that aren't equipped with transponders, which signal their location.

The internal FAA documents also revealed doubts from one worker whether air traffic controllers could truly keep some planes from hitting a turbine, and debate about which solution would best filter out the radar clutter.

None of the documents indicate workers were explicitly instructed to arrive at certain conclusions. One FAA manager emphasized that because their work would be so heavily scrutinized, their response to the radar concerns must be "iron-clad."

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