Figure 2-28. Airframe

TM-1-1520-240-BD Army CH-47D Heilcopter (NSN 1520-01-088-3869) (EIC:RCD) Manual
Page Navigation
58

TM 1-1520-240-BD 2-3. AIRFRAME. The airframe structure consists of two parts the primary structure and the secondary structure. Both are made mostly of high-strength aluminum alloy. (See Figure 2-28). a. Primary Structure. The primary structure is the skeleton framework that gives the helicopter its shape. Stringers and longerons extend fore and aft. They are supported by frames and bulkheads that extend across the width of the fuselage. Formers and beams are used where needed to support loads such as power-plants, transmissions, and landing gear. b. Secondary Structure. (Figure 2-29). The secondary structure is made up of aluminum panels that are riveted to the primary structure. The panels are stressed to help provide strength and stiffness to the helicopter. Other panels protect and provide aerodynamic fairings over components. The airframe is built in four sections cockpit, cabin fuselage, aft fuselage, and pylon. The cockpit is spliced to the cabin fuselage at station 160. The aft fuselage is spliced to the cabin fuselage at station 440. The pylon is attached to the aft fuselage at water line 72. The cockpit and fuselage sections cannot be separated. The pylon can be removed if needed to transport the helicopter. c. Cockpit. (Figure 2-30). The cockpit section contains controls and the fully adjustable pilot's and copilot's seats. The forward transmission is mounted at the top of the section; covered by a fiberglass fairing. A hinged work platform is built into each side of the fairing. Three self-tuning dynamic absorbers are installed in the cockpit section. One is in the nose and two are below the cockpit floor, under the seats. The absorbers automatically adjust themselves to lower vibration in the helicopter throughout its normal operating range. The section contains three doors. A jettisonable door is next to each seat. The main entrance door is at the aft right side of the section. There are three windshields in the cockpit pilot's, copilot's, and center. Each consists of three layers. The middle layer of all windshields is plastic. Inboard and outboard layers are either glass or plastic. The pilot's and copilot's windshield can be heated electrically for anti-icing or defogging. The center windshield can be heated for defogging only. Each windshield has a temperature sensing element to provide automatic temperature control. Figure 2-28. Airframe 2-33

Privacy Statement
Press Release
Contact