Wiring Diagram for the Piper PA-30 Twin Comanche

cowl and is picked up by a large air duct at the right rear baffle. The air is directed through a filter and on to the servo regulator. An alternate air source for the induction system contains a spring loaded door at the throat of the servo regulator. This door op- erates automatically if primary source is obstructed or manually by the push-pull control on the right side of the power control quadrant. The primary system should always be used for take-off. 7 700505 TWIN COMANCHE STRUCTURES SECTION II Structures are of sheet aluminum construction and are de- signed to ultimate load factors well in excess of normal require- ments. All components are completely zinc chromate primed and exterior surfaces are coated with acrylic lacquer. The main spars of the wings are joined with high strength butt fittings in the center of the fuselage, making in effect a continuous main spar. The spars are attached to the fuselage at the side of the fuselage and in the center of the structure; wings are also attached at the rear spar and at an auxiliary front spar. The wing airfoil section is a laminar flow type, NACA- 642A215, with maximum thickness about 40% aft of the leading edge. This permits the main spar, located at the point of max- mum thickness, to pass through the cabin under the rear seat, providing unobstructed cabin floor space ahead of the seat. LANDING GEAR The nose gear is steerable with the rudder pedals through a 4 degree arc. During retraction of the gear, the steering mecha- nism is disconnected automatically to reduce rudder pedal loads in flight. The nose gear is equipped with a hydraulic shimmy dampener. Retraction of the landing gear is accomplished through the use of an electric motor and gear train, actuating push-pull cables to each of the main gear and a tube to the nose gear. The landing gear motor is beneath the center floor panel and the selector switch on the instrument panel to the left of the power control quadrant. To guard against inadvertent movement of the landing gear selector on the ground, the handle must also be pulled aft before moving it upward. The gear selector has the shape of a wheel to .00505. SECTION II TWIN COMANCHE' MAS GEAR DOWN SPEED 150 MPH {{ ༦t a u• } distinguish it from the electric flap control which has an air- foil shape. As an added safety feature, the warning horn is connected to the gear selector switch. The horn will then op- erate if the selector is moved to the UP position with the master switch on and the weight of the airplane on the landing gear. To prevent gear retraction on the ground, an anti-retraction switch is in- stalled on the left main gear. This prevents the completion of the electric circuit to the landing gear motor until the gear strut is within 3/4 inch of full extension. GEAR DOWN 101480 Gear Selector Switch The gear indicating lights are located conveniently by the gear selector switch. The green indicating light below the selec- tor switch shows that all gear are down and locked. The amber light above the gear selector switch is the gear up indication: it will flash if the power of one engine is reduced below 12 inches of manifold pressure while the gear is up and locked. The gear up warning horn will sound when power is reduced (below approx- imately 12 inches of manifold pressure) on both engines and the gear is not down and locked. GEAR INDICATION LIGHTS ARE DIMMED WHILE THE INSTRUMENT LIGHTS ARE ON. The brakes are actuated by toe brake pedals mounted on the left set of the rudder pedals. Hydraulic brake cylinders above the brake pedals are accessible in the cockpit for ser- vicing. Parking brake valves are incorporated in each cylinder and have two cables attached from the parking brake "T" handle. To prevent inadvertent application of the parking brake in flight, a safety lock is incorporated in the valves, thus eliminating the possibility of pulling out the "T" handle until pressure is applied by use of the toe brakes. Toe brakes for the right side are available as optional equipment. 9 700505 TWIN COMANCHE SECTION II A tow bar is provided with each aircraft. When not in use it is stowed in the baggage compartment. When towing with power equipment, caution should be used not to turn the nose gear beyond its 40 degree arc as this may cause damage to the nose gear and steering mechanism. CONTROL SYSTEM Dual flight controls are provided as standard equipment. Cables connect the movable control surfaces with the rudder _edals and control columns. Directional and longitudi- nal trim is provided by an adjustable trim mechanism for the rudder and stabilator. The manual rudder trim control is located to the right of the throttle quadrant. Max-Lift electrically op- erated flaps are used on the Twin Comanche. The flaps are operated by an electric motor; they can be lowered Rudder Trim and Flap Controls 00505 10 SECTION II TWIN COMANCHE' and stopped in any desired position. The airfoil shaped flap con- trol is to the right of the power control quadrant. Located on the instrument panel is a flap position indicator marked to show the position of the flap relative to the wing. A range for take-off operation is also shown. Located in the inboard end of the right flap is a lock which holds the flap in the UP position so that it can be used as a step for entry or exit. A second lock is incorporated to prevent the flap from going full down in case a step load is applied and the up lock is not fully engaged. FUEL SYSTEM The fuel is carried in four integral fuel cells located in the leading edge sections of the wings. Capacity of the two main fuel cells is 30 gallons each, of which 27 gallons is usable. The auxiliary fuel system consists of two 15 gallon cells (all usable) installed in the wings just outboard of the main fuel cells. Wing tip tanks are available as optional equipment. Auxil- iary fuel and tip tank fuel is to be used in level flight only. The cells should be kept full of fuel during storage of the airplane to prevent accumulation of moisture and deterioration of the cells. For storage of more than ten days without fuel, the cells should be coated with light engine oil to prevent excessive drying. During normal operation use the engine driven fuel pump to draw fuel from the cell directly adjacent to that engine. How- ever, fuel can be drawn from any cell to both engines through use of the engine driven fuel pump or the electric auxiliary fuel pump. For emergency single engine operation a crossfeed is pro- vided to increase the range. When using fuel from tanks on the same side as the operating engine, the position of the fuel se- lector will remain the same as for normal operation with the 11 700505 /00505 FUEL SYSTEM 12 SERVO REGULATOR DUAL FUEL FLOW GAUGE SERVO REGULATOR TO HEATER THROTTLE MIXTURE SHUT OFF VALVE AUXILIARY FUEL PUMPS ENGINE FUEL PUMP FUEL PUMP SWITCH FUEL PUMP SWITCH MIXTURE THROTTLE ୪ ENGINE FUEL PUMP] TO LEFT ENGINE _ NORMAL FUEL FLOW > CROSSFEED FUEL FLOW FUEL SELECTORS STRAINER DRAIN KNOB TO RIGHT ENGINE CROSSFEED CROSSFEED MAIN MAIN ?. FUEL QUANTITY INDICATORS 3 TWIN COMANCHE SECTION II SECTION II TWIN COMANCHE auxiliary fuel pump off unless the engine driven pump is inoper- ative. NOTE Do not put both fuel selectors in the crossfeed position at the same time. When using fuel from cells on the opposite side of the oper- ating engine, move the fuel selector for the inoperative engine to the main or auxiliary position; then move the fuel selector for the operating engine to the crossfeed position. For single engine landing, fuel must be pumped from the main cell on the same side as the operating engine. The fuel strainers for the system are located beneath the floor panel in the center section of the fuselage. Daily draining of the strainers may be accomplished in the cockpit by opening the hinged access door located in the floor panel just aft of the fuel selector handles and pulling up on the knob located in the center of the selector valve. The general procedure for draining the fuel system is to open the strainer quick drain for several seconds with the fuel cell selector on the main cell, then to change the selector to the auxiliary cell and repeat the process. Allow enough fuel flow to clear the lines as well as the strainer. Positive fuel flow shut-off can be observed through the clear plastic tube that carries the fuel overboard. Located inside the fuel valves is a by-pass valve which will open at 1/2 psi differ- ential pressure if the strainer screen becomes blocked. Fuel quantity is indicated by two electric gauges located at the top of the instrument cluster. The instruments are connected to a transmitter unit located in each fuel cell. The gauges will indicate the amount of fuel available in the cells that are selected. 13 700505 ( TWIN COMANCHE ELECTRICAL SYSTEM SECTION II Electrical power for the Twin Comanche is supplied by a 12 volt, direct current system. Incorporated in the system is a 12 volt 50 ampere generator and 35 ampere hour battery, which furnish electrical power during operation. The battery is located behind the baggage compartment bulkhead in a sealed stainless steel battery box. Refer to the Maintenance Section for servicing of the battery. Dual generators are available as optional equip- ment. Electrical switches for the various systems are located _ on the lower left instrument panel. The circuit breakers, located under the floorboard aft of the nose wheel well, automatically Break the electrical circuit if an overload should occur. To set the circuit breakers simply push in the reset button. It may be necessary to allow approximately two minutes before resetting the breakers. Corrective action should be taken in event of continual circuit breaker popping. It is possible to manually trip the breaker by pulling out on the reset button. MACUUM SYSTEM Suction for the vacuum operated gyro instruments is supplied by two engine driven (dry type) vacuum pumps, interconnected to form a single system. Either vacuum pump has sufficient capacity to operate the gyro instruments. If suction is lost from one or the other side a check valve automatically closes and suction is supplied by the remaining system. A vacuum gauge is installed in the instrument panel to pro- vide a constant indication of vacuum source. Incorporated in the instrument are two red indicators (right and left systems). During normal operation the indicators are not visible, but if vacuum is lost, for example on the right side, then the right indicator will J0505 14