Figure 88 - FRONT VIEW OF POWER PLANT
8. POWER PLANT.
(1) GENERAL. - This airplane is equipped with two 14-cylinder Wright Model R-2600-23 engines, each weighing 1950 pounds. Each engine produces 1600 brake horsepower at sea level take-off at 2400 rpm. The engines are of the radial, air-cooled, double-row cylinder type. One engine is mounted on the front of each engine nacelle by a welded tube engine mount which attaches at two points on the nacelle fire wall and at two points on the front shear web. (See figure 89.) The ring section of the mount carries the engine which is attached at seven points. Each engine is housed by an antidrag ring formed of sheet aluminum alloy. Immediately behind the antidrag ring are the cowl flaps which open to permit engine cooling. An engine accessories cowling covers the space between the cowl flaps and the fire wall.
(2) COMPLETE ENGINE SECTION. - The complete engine section of the nacelle is composed of the engine and the engine mount and everything attached to them except the propeller and anti-drag ring. The nacelle is designed so thatthe complete engine section forward of the fire wall, including fuel and oil lines, may be handled as a quickly detachable unit.
(3) ACCESSORIES. - Engine accessories are treated under the paragraphs of this section dealing with the system- of which they are part. For example, magnetos and generator are covered in paragraph 17, Electrical System. The starter is treated in paragraph 11, Starting System. The carburetor and fuel pump are covered in paragraph 13, Fuel System. The oil pump is treated in paragraph 12, Oil System; the vacuum pump in paragraph 14, Instruments; and the hydraulic pump in paragraph 16, Hydraulic System.
(1) GROUND RUN-IN OF ENGINES.
(a) GENERAL. - After general replacement of internal wearing parts (bearings, bushings, pistons, rings, and similar parts), test-run engines to ensure proper functioning. Block-test engines if equipment is available. Otherwise, when running-in and testing of engines are necessary, operate the engines when installed in the airplane, using the regular airplane instruments for determining proper operation. To obtain maximum cooling, remove the cowling and keep the propeller in low pitch.
9. ENGINE AND PROPELLER CONTROLS.
a. DESCRIPTION (See Figures 108, 110, 111, and 112.)
(1) GENERAL. - Engine and propeller controls are grouped on the left side of the pilot's cockpit. Cables attached to control handle pulleys provide the means of adjusting the engine and propeller controls. From the control handle pulleys, the cables run aft to the mainspar in the fuselage, outboard to the left-hand side of their respective nacelles, and down to the differential pulley beam aft of the fire wall. Cables provide the operation of the controls forward of the fire wall. All control cables are of 3/32 inch 7 by 7 preformed flexible steel wire. For identification, colored bands of paint will be found on all cables.
Figure 108 - INSTALLED ENGINE CONTROLS
(2) ENGINE COWL AND OIL COOLER FLAP CONTROLS. (See figure 109.) - The engine cowl flaps are actuated by hydraulic pressure and are controlled by valves located on the panel at the right side of the pilot's seat. Upper cowl flaps for each engine are controlled in unison by a single valve handle. Lower cowl flaps for each engine are controlled by individual valve handles. The oil cooler flaps are connected by cables to the lower cowl flap mechanism and operate simultaneously with the lower cowl flaps. To open the cowl flaps, move the respective control to OPEN position; when the flaps are open as desired, return the control to NEUTRAL position. To avoid buffeting, the upper cowl flaps should be closed at all times in flight and opened only while the engines are running on the ground.
Figure 113 - PROPELLERS FEATHERED AND UNFEATHERED
(1) GENERAL. (See figure 113.)-Each engine is equipped with a Hamilton Standard, hydromatic, full-feathering propeller. The nominal diameter of each propeller is 11 feet 4 inches. Each propeller consists of a 23E50 hub and three 6353A-21 blades. A propeller anti-icer system is provided.
(2) FEATHERING SYSTEM. -Fluid for operating the propeller feathering system in each nacelle is provided by the engine oil container in each inner wing panel. A sump at the bottom of the oil container provides a one-gallon oil supply which is available to the propeller feathering system only. From this sump the oil is directed to an electrically operated pump which forces the oil under pressure to a cable controlled propeller governor mounted on the front section of the engine. The pressure of the oil between the pump and the governor may range up to 500 pounds per square inch for feathering and to 600 pounds per square inch for unfeathering the propeller. A switch is provided for each propeller. After pushing the respective switch for the propeller to be feathered, the switch will automatically release when the propeller blades reach their full feathered position. To unfeather the propeller, push in the switch and hold until the engine windmills at 600 to 800 rpm. Then release the switch.
Figure 114 - PROPELLER CONTROL FORCES