Abstract: There is disclosed tree trimmer apparatus for installation on a helicopter or the like including a boom hanging vertically downward from the helicopter carrying a plurality of circular saws arranged with their blades nearly adjacent over a length of at least twenty feet on the boom, which is attached to the helicopter in a manner to be constrained against rotation about a vertical axis and to have rotational movement about a horizontal axis at right angles to the normal direction of motion of said helicopter; the blades are preferably powered by a hydraulic motor with groups of five 24-inch blades being driven through belts by one hydraulic motor provided with hydraulic fluid under pressure from a pump in the helicopter. A foot at the bottom of the boom extends to the rear and permits the apparatus to be landed with the bottom of the boom on a landing surface by maneuvering the helicopter backward to lay the boom and saw blades on the ground in front of the helicopter.