Production of Lockheed Martin Corp's F-35 joint strike fighter, the costliest arms purchase in history, should be slowed because of the potential number of cracks and hot spots turning up in fatigue testing and analysis, the Pentagon F-35 program director said.

The analyzed hot spots that have arisen in the last 12 months or so in the program have surprised us at the amount of change and at the cost, U.S. Navy Vice Admiral David Venlet said in an interview with Web-based publication AOL Defense.

The Pentagon program office confirmed the vice admiral's quotes on Friday.

Most of them are little ones. But when you bundle them all up and package them, and look at where they are in the airplane and how hard they are to get at after you buy the jet, the cost burden of that is what sucks the wind out of your lungs, Venlet added.

I believe it's wise to sort of temper production for a while here, until we get some of these heavy years of learning under our belt and get that managed right, he said.

Lockheed did not immediately respond to a request for comment.

The Pentagon currently plans to buy more than 2,400 F-35 aircraft in three models, at a cost of more than $382 billion.

Lockheed, the Pentagon's No. 1 contractor by sales, has projected the F-35 would account for just over 20 percent of its revenue when it hits full production.

The plane is currently in early production.

(This story corrects the name spelling to Venlet throughout. Also corrects the last paragraph to make the word revenue, not profit.)

(Reporting by Jim Wolf; Editing by Vicki Allen)