Updated 9/10/2009

AeroVironment Inc.’s share price plunged by more than a third Tuesday, a day after the developer of unmanned aircraft systems said its third-quarter net income fell 24 percent on higher expenses. The company also warned of lower revenue growth due to the slowing economy.

After Monday’s market close, the Monrovia company reported net income of $4.5 million (21 cents per share), compared with $6 million (28 cents) a year ago. Revenues rose 7.6 percent to $52.2 million. Both figures were lower than the consensus of analysts surveyed by Thomson First Cal, who expected earnings of 28 cents per share on revenue of $65.3 million.

AeroVironment’s funded backlog was $139 million as of Jan. 31. Even so, the company now expects 2009 revenue growth of between 11 percent and 16 percent, down from its previous forecast of 20 percent to 25 percent. That works out to between $239 million to $250 million in revenue, less than the more than $266 million analysts had expected.

“Even with our backlog, our view of the balance of the year requires that we lower our revenue outlook for fiscal 2009,” said Chief Executive Tim Conver in a statement. “This is driven largely by current economic conditions as well as the timing of the receipt and shipment of customer orders.”

AeroVironment shares closed down $10.28, or 33 percent, to $20.30 Tuesday on the Nasdaq.