Federal aviation officials say a small plane that crashed in a corn field in northwest Iowa, killing all three Wisconsin men on board, was low on fuel.The National Transportation Safety Board says the single - engine piper had two 25 - gallon fuel tanks.After the crash, investigators drained 1 cup of fuel from the tank under the left wing and 2 and a half cups from the tank under the right wing.The plane crashed on June 23 in O'Brien County.The three men on board were flying from to South Dakota on a hunting trip.