TYPE OF CONSTRUCTION

TM 1-1520-265-23 a. Stations. Stations (STA) are distances from a point in front of the helicopter nose. The first station is zero (0.00). b. Waterlines. Waterlines (WL) are distances from a point below the helicopter. c. Buttlines. Buttlines (BL) are distances from the center of the helicopter. They start at the center and show the distance to each side of the helicopter. Buttlines will be either to the left or right side. These dimensions help you find any point on the helicopter. Each point shown on the following pages is a part of the helicopter you can see. 1.2. TYPE OF CONSTRUCTION. NOTE The following paragraphs describe the type of construction and materials used in the manufacture of the major H-60 helicopter series components. 1.2.1. Rotor System. Four main rotor blades are installed on the main rotor head. The main rotor blade has a pressurized titanium spar, Nomex honeycomb core, fiberglass skin, nickel and titanium abrasion strips, a removable swept-back tip fairing, and a resistive heating mat used when the blade de-ice system is activated. A titanium cuff and expandable pins attach the blade to the rotor head. The main rotor head transmits the movements of the flight controls to the four main rotor blades. The main rotor head turns in a counter clockwise direction. The head is supported by the main rotor shaft extension that is splined to the main transmission main shaft, which drives the head. The canted tail rotor head is driven by the tail gearbox which is driven by a drive shaft from the main transmission. The tail rotor blades are attached to the tail rotor head. Tail rotor blades are built around two graphite composite spars running from tip-to-tip and crossing each other at the center to form the four blades. The blade spars are covered with crossply fiberglass to form the airfoil shape. Polyurethane and nickel abrasion strips are bonded to the leading edge of the blades. 1.2.2. Drive System. The transmission system carries engine torque to the main rotor and the tail rotor. It consists of a main transmission with oil cooler, intermediate gearbox, and drive shafts. The main transmission drives the main rotor, tail rotor, main transmission oil cooler fan, No. 1 and No. 2 hydraulic pump modules, and No. 1 and No. 2 generators. The intermediate gearbox, driven by tail rotor drive shafts, is mounted at the base of the pylon. The intermediate gearbox carries main transmission torque to the tail gearbox. The tail gearbox, mounted at the top of the pylon, holds the tail rotor head to which the tail rotor blades are attached. 1.2.3. Airframe and Landing Gear System. The helicopter airframe is divided into six sections: cockpit (nose section), cabin, transition section, tail cone, tail rotor pylon, and main rotor pylon. The primary structure is aluminum alloy. Some titanium and steel are used for firewalls and various fittings. Nonstructural members are primarily made of reinforced plastic. The fuselage is semi-monocoque construction with horizontal anti-plough beams extending through the tub from the cockpit to the transition section. 1-11