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RESTRICTED T.O. No. 02-35GC-1 one magneto should not exceed 100 rpm. The difference in timing of the two magnetos results in a difference in loss in rpm, or manifold pressure, when operating on either magneto alone. This check should be made in as short a time as possible, and should not exceed fifteen seconds. (2) At the start of the day's flying it is necessary to check the "Off" position of the ignition switch to assure the proper connection of the ground wires. This check should be made at the end of the engine "warm-up" period with the propeller in full low pitch and the engine turning over approximately 700 rpm. The switch should be turned to the "Off" position momentarily to note whether or not the engine stops firing, and immediately returned to the "Both On" position. Two or three seconds is ample time for the switch to remain in the "Off" position. d. Manifold Pressure Gage Drain. - When warming up the engine, the shut-off cock for the manifold pressure gage drain will be opened for a few seconds to clear the line of liquids and vapors. This will be done at idling speeds only. e. Clutch Mechanism for Two-Speed Superchargers. - To prevent accumulation of centrifuge sludge and dirt in the two-speed supercharger clutch mechanism, and to check for satisfactory operation, the clutches will be shifted immediately following each engine warm-up. To accomplish the shifting operation, set the propeller governor in full low pitch (high rpm) position, set the engine speed at 1500 rpm, move the supercharger control lever to the "High" position and lock. Open the throttle to obtain not over 30 inches mercury manifold pressure. When the engine speed has stabilized, observe the manifold pressure and immediately shift the supercharger control to the "Low" position without moving the throttle. A sudden decrease in manifold pressure is an indication that the two-speed supercharger drive is operating properly. 5. Take-Off. a. R-1820-65, -73 and -97 Engines. (1) Do not start take-off with the cylinder head temperatures above 205 degrees C (401 degrees F). (2) Adjust oil cooler shutters to "Full Open." (3) The turbo-supercharger will normally not be used for take-off. However, if it is necessary to use the turbo to obtain the desired take-off manifold pressure, the following instructions will be complied with after warm-up and prior to take-off: (a) Open throttle on one engine to full throttle. Adjust the waste-gate regulator to obtain take-off manifold pressure, adjust propeller control to obtain take-off rpm, lock the waste-gate regulator control and propeller control, and return the throttle to idling position. Repeat this procedure for each engine. CAUTION: Warm-up and ground test running of these engines will be held to an absolute minimum. (b) A minor variation of ± one (1) inch mercury manifold pressure is permissible. In multi-engine airplanes, if one supercharger is used, all should be used. (4) For take-off leave all other controls set as in warm-up, release wheel brakes and open all throttles simultaneously to full throttle. (5) Limit full power to one minute unless in an emergency, when full power for a maximum of five minutes is permissible. b. R-1820-71 and -87 Engines. (1) Do not start take-off with the cylinder head temperatures above 205 degrees C (401 degrees F). (2) Adjust oil cooler shutters to "Full Open." (3) Always take-off R-1820-87 engine in low supercharger ratio. (4) Limit full power to one minute unless in an emergency, when full power for a maximum of five minutes is permissible. 6. Flight. a. The rpm, cylinder temperatures, oil temperature and oil pressure give the most satisfactory indication of the engine's performance. If any of these appears irregular, the engine should be throttled, and if the cause cannot be eliminated, a landing should be made to investigate and remove the trouble. b. To avoid excessively lean mixtures and possible damage, always set mixture control in "Auto-Rich" before shifting fuel supply tanks, and never permit a fuel supply tank to run dry before shifting to an alternate tank. c. R-1820-65, -73, and -97 Engines. (1) After take-off, the automatic supercharger regulator should be adjusted to hold the pressure specified for the climb. Normally, to reduce power for climb, the turbo-supercharger control should first be moved toward the "Off" position. When the control is in the "Off" position and a further reduction of power is desired, move the throttle toward the "Closed" position to give the proper manifold pressure. CAUTION: Excessive supercharging will cause serious damage to the engine. - 5 - RESTRICTED