Wesco Aircraft Holdings Inc. announced that John Jumper has resigned from the Valencia company’s board of directors as of March 25. In leaving the board, Jumper cited competing demands on his time due to his position as chief executive and president of SAIC Inc., a scientific, engineering, and technology applications company based in McLean, Va. Wesco is seeking a successor to fill the vacancy and will operate with eight directors until a replacement is found. Jumper’s guidance and counsel have been of great value to Wesco, said Chief Executive and Chairman Randy Snyder. Shares in Wesco closed up 12 cents, or nearly 1 percent, to $14.62 on the New York Stock Exchange.