Systems Description for Cessna 152

MODEL 152 SECTION 7 AIRPLANE & SYSTEMS DESCRIPTIONS horizontal stabilizer also contains the elevator trim tab actuator. Con- struction of the elevator consists of a main spar and bellcrank, left and right wrap-around skin panels, and a formed trailing edge skin on the left half of the elevator; the entire trailing edge of the right half is hinged and forms the elevator trim tab. The leading edge of both left and right elevator tips incorporate extensions which contain balance weights. FLIGHT CONTROLS The airplane's flight control system (see figure 7-1) consists of conventional aileron, rudder, and elevator control surfaces. The control surfaces are manually operated through mechanical linkage using a control wheel for the ailerons and elevator, and rudder/brake pedals for the rudder. Extensions are available for the rudder/brake pedals. They consist of a rudder pedal face, two spacers and two spring clips. To install an exten- sion, place the clip on the bottom of the extension under the bottom of the rudder pedal and snap the top clip over the top of the rudder pedal. Check that the extension is firmly in place. To remove the extensions, reverse the above procedures. TRIM SYSTEM A manually-operated elevator trim tab is provided. Elevator trimming is accomplished through the elevator trim tab by utilizing the vertically mounted trim control wheel. Forward rotation of the trim wheel will trim nose-down; conversely, aft rotation will trim nose-up. instruments positioned below the pilot's control wheel. The electrical switches, panel and radio light rheostat knob, ignition and master switches, primer, and parking brake control are located around these instruments. The engine controls, wing flap switch, and cabin air and heat control knobs are to the right of the pilot, along the upper edge of the subpanel. Directly below these controls are the elevator trim control wheel, trim position indicator, microphone, and circuit breakers. A map compartment is on the extreme right side of the subpanel. For details concerning the instruments, switches, circuit breakers, and controls on this panel, refer in this section to the description of the systems to which these items are related. GROUND CONTROL Effective ground control while taxiing is accomplished through nose wheel steering by using the rudder pedals; left rudder pedal to steer left and right rudder pedal to steer right. When a rudder pedal is depressed, a spring-loaded steering bungee (which is connected to the nose gear and to the rudder bars) will turn the nose wheel through an arc of approximately 8.5° each side of center. By applying either left or right brake, the degree of turn may be increased up to 30° each side of center. INSTRUMENT PANEL The instrument panel (see figure 7-2) is designed to place the primary flight instruments directly in front of the pilot. The gyro-operated flight instruments are arranged one above the other, slightly to the left of the control column. To the left of these instruments are the airspeed indicator, turn coordinator, and suction gage. The clock, altimeter, rate-of-climb indicator, and navigation instruments are above and/or to the right of the control column. Avionics equipment is stacked approximately on the centerline of the panel, with space for additional equipment on the lower right side of the instrument panel. The right side of the panel also contains the tachometer, ammeter, over-voltage light, and additional instruments such as a flight hour recorder. A subpanel, under the primary instrument panel, contains the fuel quantity indicators, cigar lighter, and engine 7-8 Figure 7-3. Wing Flap System 7-9 SECTION 7 AIRPLANE & SYSTEMS DESCRIPTIONS CESSNA MODEL 152 CESSNA MODEL 152 SECTION 7 AIRPLANE & SYSTEMS DESCRIPTIONS Moving the airplane by hand is most easily accomplished by attaching a tow bar to the nose gear strut. If a tow bar is not available, or pushing is required, use the wing struts as push points. Do not use the vertical or horizontal surfaces to move the airplane. If the airplane is to be towed by vehicle, never turn the nose wheel more than 30° either side of center or structural damage to the nose gear could result. The minimum turning radius of the airplane, using differential braking and nose wheel steering during taxi, is approximately 24 feet 8 inches. To obtain a minimum radius turn during ground handling, the airplane may be rotated around either main landing gear by pressing down on the tailcone just forward of the vertical stabilizer to raise the nose wheel off the ground. WING FLAP SYSTEM The wing flaps are of the single-slot type (see figure 7-3), and are extended or retracted by positioning the wing flap switch lever on the instrument panel to the desired flap deflection position. The switch lever is moved up or down in a slot in the instrument panel that provides mechanical stops at the 10° and 20° positions. For flap settings greater than 10°, move the switch lever to the right to clear the stop and position it as desired. A scale and pointer on the left side of the switch lever indicates flap travel in degrees. The wing flap system circuit is protected by a 15- ampere circuit breaker, labeled FLAP, on the right side of the instrument panel. LANDING GEAR SYSTEM The landing gear is of the tricycle type with a steerable nose wheel and two main wheels. The landing gear may be equipped with wheel fairings. Shock absorption is provided by the tubular spring-steel main landing gear struts and the air/oil nose gear shock strut. Each main gear wheel is equipped with a hydraulically actuated disc-type brake on the inboard side of each wheel. When wheel fairings are installed an aerodynamic fairing covers each brake. BAGGAGE COMPARTMENT The baggage compartment consists of the area from the back of the pilot and passenger's seats to the aft cabin bulkhead. Access to the baggage compartment is gained from within the airplane cabin. A baggage net with six tie-down straps is provided for securing baggage and is attached by tying the straps to tie-down rings provided in the airplane. When loading the airplane, children should not be placed or permitted in the baggage compartment, unless a child's seat is installed, and any material that might be hazardous to the airplane or occupants should not be placed anywhere in the airplane. For baggage area dimensions, refer to Section 6. SEATS The seating arrangement consists of two separate adjustable seats for the pilot and passenger and, if installed, a child's seat in the rear cabin area. The pilot's and passenger's seats are available in two designs: four- way and six-way adjustable. Four-way seats may be moved forward or aft, and the seat back angle changed. To position either seat, lift the lever under the inboard corner of the seat, slide the seat into position, release the lever, and check that the seat is locked in place. To adjust the seat back, pull forward on the knob under the center of the seat and apply pressure to the back. To return the seat back to the upright position, pull forward on the exposed portion of the seat back frame. Both seat backs will also fold full forward. The six-way seats may be moved forward or aft, adjusted for height, and the seat back angle changed. Position either seat by lifting the tubular handle under the inboard front corner of the seat bottom and slide the seat to the desired position. Release the lever and check that the seat is locked in place. The seats may be raised or lowered two inches, in one inch steps, and should be adjusted prior to flight. To raise or lower either seat, pull forward on a "T" handle under the seat near the inboard corner, force the seat down against spring tension or allow spring tension to raise it to the desired position, release the "T" handle, and then allow the seat to move until it locks in place. Seat back angle is adjustable by rotating a lever on the rear inboard corner of each seat. To adjust either seat back, rotate the lever aft and apply pressure against the back until it stops moving; then release the lever. The seat back may be returned to the upright position by pulling forward on the exposed portion of the lower seat back frame. Check that the release lever has returned to its vertical position. Both seat backs will fold full forward. A child's seat is available for installation in the rear of the cabin. The seat back is secured to the cabin sidewalls, and the seat bottom is attached to brackets on the floor. This seat is non-adjustable. 7-10 7-11 SECTION 7 AIRPLANE & SYSTEMS DESCRIPTIONS CESSNA MODEL 152 CESSNA MODEL 152 NARROW RELEASE STRAP (Pull up when lengthening harness) FREE END OF HARNESS (Pull down to tighten) SHOULDER HARNESS CONNECTING LINK (Snap onto retaining stud on STANDARD SHOULDER seat belt link to attach harness) SEAT BELT BUCKLE HALF (Non adjustable) SEAT BELT LINK HALF AND SHOULDER HARNESS RETAINING STUD FREE END OF SEAT BELT (Pull to tighten) HARNESS SEAT BELT BUCKLE (Non adjustable) SEAT BELT/SHOULDER HARNESS ADJUSTABLE LINK (Position link just below shoulder level; pull link and harness down- ward to connect to seat belt buckle) (PILOT'S SEAT SHOWN) SEAT BELT/SHOULDER HARNESS WITH INERTIA REEL Figure 7-4. Seat Belts and Shoulder Harnesses SECTION 7 AIRPLANE & SYSTEMS DESCRIPTIONS SEAT BELTS AND SHOULDER HARNESSES All seat positions are equipped with seat belts (see figure 7-4). The pilot's and passenger's seats are also equipped with separate shoulder harnesses. Integrated seat belt/shoulder harnesses with inertia reels can be furnished for the pilot's and passenger's seat positions if desired. SEAT BELTS The seat belts used with the pilot's seat, passenger's seat, and the child's seat (if installed) are attached to fittings on the floorboard. The buckle half of the seat belt is inboard of each seat and has a fixed length; the link half of the belt is outboard and is the adjustable part of the belt. To use the seat belts for the pilot's and passenger's seats, position the seat as desired, and then lengthen the link half of the belt as needed by grasping the sides of the link and pulling against the belt. Insert and lock the belt link into the buckle. Tighten the belt to a snug fit by pulling the free end of the belt. The seat belt for the child's seat (if installed) is used in the same manner as the belts for the pilot's and passenger's seats. To release the seat belts, grasp the top of the buckle opposite the link and pull upward. SHOULDER HARNESSES Each shoulder harness is attached to a rear doorpost above the window line and is stowed behind a stowage sheath above the cabin door. To stow the harness, fold it and place it behind the sheath. No harness is available for the child's seat. The shoulder harnesses are used by fastening and adjusting the seat belt first. Then, lengthen the harness as required by pulling on the connecting link on the end of the harness and the narrow release strap. Snap the connecting link firmly onto the retaining stud on the seat belt link half. Then adjust to length. Removing the harness is accomplished by pulling upward on the narrow release strap and removing the harness connecting link from the stud on the seat belt link. In an emergency, the shoulder harness may be removed by releasing the seat belt first and allowing the harness, still attached to the link half of the seat belt, to drop to the side of the seat. Adjustment of the shoulder harness is important. A properly adjusted harness will permit the occupant to lean forward enough to sit completely erect, but prevent excessive forward movement and contact with objects during sudden deceleration. Also, the pilot will want the freedom to reach all controls easily. 7-12 7-13 SECTION 7 AIRPLANE & SYSTEMS DESCRIPTIONS CESSNA MODEL 152 CESSNA MODEL 152 SECTION 7 AIRPLANE & SYSTEMS DESCRIPTIONS INTEGRATED SEAT BELT/SHOULDER HARNESSES WITH INERTIA REELS Integrated seat belt/shoulder harnesses with inertia reels are availa- ble for the pilot and front seat passenger. The seat belt/shoulder harnesses extend from inertia reels located in the upper cabin sidewall just aft of each cabin door to attach points outboard of the front seats. A separate seat belt half and buckle is located inboard of the seats. Inertia reels allow complete freedom of body movement. However, in the event of a sudden deceleration, they will lock automatically to protect the occupants. To use the seat belt/shoulder harness, position the adjustable metal link on the harness at about shoulder level, pull the link and harness downward, and insert the link in the seat belt buckle. Adjust belt tension across the lap by pulling upward on the shoulder harness. Removal is accomplished by releasing the seat belt buckle, which will allow the inertia reel to pull the harness outboard of the seat. ENTRANCE DOORS AND CABIN WINDOWS Entry to, and exit from the airplane is accomplished through either of two entry doors, one on each side of the cabin (refer to Section 6 for cabin and cabin door dimensions). The doors incorporate a recessed exterior and interior door handle, a key-operated door lock (left door only), a door stop mechanism, and an openable window. To open the doors from outside the airplane, utilize the recessed door handle near the aft edge of each door. Grasp the forward edge of the handle and pull out. To close or open the doors from inside the airplane, use the recessed door handle and arm rest. Both cabin doors should be checked for security prior to flight, and should not be opened intentionally during flight. NOTE Accidental opening of a cabin door in flight due to improp- er closing does not constitute a need to land the airplane. The best procedure is to set up the airplane in a trimmed condition at approximately 65 knots, momentarily shove the door outward slightly, and forcefully close the door. Exit from the airplane is accomplished by grasping the forward edge of the door handle and pulling. To lock the airplane, lock the right cabin door from the inside by lifting up on the lever near the aft edge of the door, close the left cabin door, and using the ignition key, lock the door. Both cabin doors are equipped with openable windows. The windows are held in the closed position by a detent equipped latch on the lower edge of the window frame. To open either window, rotate the latch upward. The windows are equipped with a spring-loaded retaining arm which will help rotate the window outward, and hold it there. If required, the windows may be opened at any speed up to 143 knots. All other cabin windows are of the fixed type and cannot be opened. Two additional fixed windows may be installed in the cabin top. CONTROL LOCKS A control lock is provided to lock the ailerons and elevator control surfaces in a neutral position and prevent damage to these systems by wind buffeting while the airplane is parked. The lock consists of a shaped steel rod with a red metal flag attached to it. The flag is labeled CONTROL LOCK, REMOVE BEFORE STARTING ENGINE. To install the control lock, align the hole in the top of the pilot's control wheel shaft with the hole in the top of the shaft collar on the instrument panel and insert the rod into the aligned holes. Proper installation of the lock will place the red flag over the ignition switch. In areas where high or gusty winds occur, a control surface lock should be installed over the vertical stabilizer and rudder. The control lock and any other type of locking device should be removed prior to starting the engine. ENGINE The airplane is powered by a horizontally-opposed, four-cylinder, overhead-valve, air-cooled, carbureted engine with a wet sump oil system. The engine is a Lycoming Model O-235-L2C and is rated at 110 horsepower at 2550 RPM. Major engine accessories (mounted on the front of the engine) include a starter, a belt-driven alternator, and an oil cooler. Dual magnetos are mounted on an accessory drive pad on the rear of the engine. Provi- sions are also made for a vacuum pump and full flow oil filter. ENGINE CONTROLS Engine power is controlled by a throttle located on the lower center portion of the instrument panel. The throttle operates in a conventional manner; in the full forward position, the throttle is open, and in the full aft position, it is closed. A friction lock, which is a round knurled disk, is located at the base of the throttle and is operated by rotating the lock clockwise to increase friction or counterclockwise to decrease it. 7-14 7-15 SECTION 7 AIRPLANE & SYSTEMS DESCRIPTIONS CESSNA MODEL 152 CESSNA MODEL 152 SECTION 7 AIRPLANE & SYSTEMS DESCRIPTIONS The mixture control, mounted above the right corner of the control pedestal, is a red knob with raised points around the circumference and is equipped with a lock button in the end of the knob. The rich position is full forward, and full aft is the idle cut-off position. For small adjustments, the control may be moved forward by rotating the knob clockwise, and aft by rotating the knob counterclockwise. For rapid or large adjustments, the knob may be moved forward or aft by depressing the lock button in the end of the control, and then positioning the control as desired. ENGINE INSTRUMENTS Engine operation is monitored by the following instruments: oil pressure gage, oil temperature gage, and a tachometer. The oil pressure gage, located on the subpanel, is operated by oil pressure. A direct pressure oil line from the engine delivers oil at engine operating pressure to the oil pressure gage. Gage markings indicate that minimum idling pressure is 25 PSI (red line), the normal operating range is 60 to 90 PSI (green arc), and maximum pressure is 100 PSI (red line). Oil temperature is indicated by a gage located on the subpanel. The gage is operated by an electrical-resistance type temperature sensor which receives power from the airplane electrical system. Oil temperature limitations are the normal operating range (green arc) which is 38°C (100°F) to 118°C (245°F), and the maximum (red line) which is 118°C (245°F). The engine-driven mechanical tachometer is located near the upper center portion of the instrument panel. The instrument is calibrated in increments of 100 RPM and indicates both engine and propeller speed. An hour meter below the center of the tachometer dial records elapsed engine time in hours and tenths. Instrument markings include a normal operating range (green arc) of 1900 to 2550 RPM, and a maximum (red line) of 2550 RPM. NEW ENGINE BREAK-IN AND OPERATION The engine underwent a run-in at the factory and is ready for the full range of use. It is, however, suggested that cruising be accomplished at 65% to 75% power until a total of 50 hours has accumulated or oil consumption has stabilized. This will ensure proper seating of the rings. The airplane is delivered from the factory with corrosion preventive oil in the engine. If, during the first 25 hours, oil must be added, use only aviation grade straight mineral oil conforming to Specification No. MIL- L-6082. ENGINE OIL SYSTEM Oil for engine lubrication is supplied from a sump on the bottom of the engine. The capacity of the engine sump is six quarts (one additional quart is required if a full flow oil filter is installed). Oil is drawn from the sump through an oil suction strainer screen into the engine-driven oil pump. From the pump, oil is routed to a bypass valve. If the oil is cold, the bypass valve allows the oil to bypass the oil cooler and go directly from the pump to the oil pressure screen (full flow oil filter, if installed). If the oil is hot, the bypass valve routes the oil out of the accessory housing and into a flexible hose leading to the oil cooler on the front side of the left forward engine baffle. Pressure oil from the cooler returns to the accessory housing where it passes through the pressure strainer screen (full flow oil filter, if installed). The filter oil then enters a pressure relief valve which regulates engine oil pressure by allowing excessive oil to return to the sump, while the balance of the pressure oil is circulated to various engine parts for lubrication. Residual oil is returned to the sump by gravity flow. An oil filler cap/oil dipstick is located at the rear of the engine on the right side. The filler cap/dipstick is accessible through an access door in the engine cowling. The engine should not be operated on less than four quarts of oil. To minimize loss of oil through the breather, fill to five quarts for normal flights of less than three hours. For extended flight, fill to six quarts (dipstick indication only). For engine oil grade and specifications, refer to Section 8 of this handbook. An oil quick-drain valve is available to replace the drain plug in the oil sump drain port, and provides quicker, cleaner draining of the engine oil. To drain the oil with this valve installed, slip a hose over the end of the valve and push upward on the end of the valve until it snaps into the open position. Spring clips will hold the valve open. After draining, use a suitable tool to snap the valve into the extended (closed) position and remove the drain hose. IGNITION-STARTER SYSTEM Engine ignition is provided by two engine-driven magnetos, and two spark plugs in each cylinder. The right magneto fires the lower right and the upper left spark plugs, and the left magneto fires the lower left and upper right spark plugs. Normal operation is conducted with both magne- tos due to the more complete burning of the fuel-air mixture with dual ignition. Ignition and starter operation is controlled by a rotary type switch located on the left subpanel. The switch is labeled clockwise, OFF, R, L, BOTH, and START. The engine should be operated on both magnetos (BOTH position) except for magneto checks. The R and L positions are for 7-16 7-17 SECTION 7 AIRPLANE & SYSTEMS DESCRIPTIONS CESSNA MODEL 152 checking purposes and emergency use only. When the switch is rotated to the spring-loaded START position, (with the master switch in the ON position), the starter contactor is energized and the starter will crank the engine. When the switch is released, it will automatically return to the BOTH position. AIR INDUCTION SYSTEM The engine air induction system receives ram air through an intake in the lower portion of the engine cowling. The intake is covered by an air filter which removes dust and other foreign matter from the induction air. Airflow passing through the filter enters an airbox. After passing through the airbox, induction air enters the inlet in the carburetor which is under the engine, and is then ducted to the engine cylinders through intake manifold tubes. In the event carburetor ice is encountered or the intake filter becomes blocked, alternate heated air can be obtained from the muffler shroud through a duct to a valve, in the airbox, operated by the carburetor heat control on the instrument panel. Heated air from the muffler shroud is obtained from an unfiltered outside source. Use of full carburetor heat at full throttle will result in a loss of approximately 150 to 200 RPM. EXHAUST SYSTEM Exhaust gas from each cylinder passes through riser assemblies to a muffler and tailpipe on the right side of the engine. The muffler is constructed with a shroud around the outside which forms a heating chamber for carburetor heat and cabin heater air. CARBURETOR AND PRIMING SYSTEM The engine is equipped with an up-draft, float-type, fixed jet carburetor mounted on the bottom of the engine. The carburetor has an idle cut-off mechanism and a manual mixture control. Fuel is delivered to the carburetor by gravity flow from the fuel system. In the carburetor, fuel is atomized, proportionally mixed with intake air, and delivered to the cylinders through intake manifold tubes. The proportion of atomized fuel to air is controlled, within limits, by the mixture control on the instrument panel. For starting, the engine is equipped with a manual priming system. The primer is actually a small pump which draws fuel from the fuel strainer when the plunger is pulled out, and injects it into the cylinder intake ports when the plunger is pushed back in. The plunger knob, on the instrument panel, is equipped with a lock and, after being pushed full in, must be rotated either left or right until the knob cannot be pulled out. CESSNA MODEL 152 COOLING SYSTEM SECTION 7 AIRPLANE & SYSTEMS DESCRIPTIONS Ram air for engine cooling enters through two intake openings in the front of the engine cowling. The cooling air is directed around the cylinders and other areas of the engine by baffling, and is then exhausted through an opening at the bottom aft edge of the cowling. No manual cooling system control is provided. A winterization kit is available for the airplane. The kit consists of two cover plates to partially cover the cowl nose cap opening, two placards to be installed on the cover plates, insulation for the engine crankcase breather line, and a placard to be installed on the map compartment door. This equipment should be installed for operations in temperatures con- sistently below -7°C (20°F). Once installed, the crankcase breather insula- tion is approved for permanent use regardless of temperature. PROPELLER The airplane is equipped with a two-bladed, fixed-pitch, one-piece forged aluminum alloy propeller which is anodized to retard corrosion. The propeller is 69 inches in diameter. FUEL SYSTEM The airplane may be equipped with either a standard fuel system or long range system (see figure 7-6). Both systems consist of two vented fuel FUEL QUANTITY DATA (U. S. GALLONS) TANKS TOTAL USABLE FUEL ALL FLIGHT CONDITIONS TOTAL UNUSABLE FUEL TOTAL FUEL VOLUME 24.5 1.5 26.0 (13 Gal. Each) LONG RANGE (19.5 Gal. Each) 37.5 STANDARD 1.5 39.0 7-18 Figure 7-5. Fuel Quantity Data 7-19 SECTION 7 AIRPLANE & SYSTEMS DESCRIPTIONS VENT FILLER CAP LEFT FUEL TANK TO CYLINDER INTAKE PORTS FUEL FUEL SHUTOFF VALVE 24.5 GALS ON © ENGINE PRIMER CODE FUEL SUPPLY VENT MECHANICAL LINKAGE OFF FUEL STRAINER CARBURETOR TO ENGINE CYLINDERS CESSNA MODEL 152 VENTED FILLER CAP RIGHT FUEL TANK THROTTLE MIXTURE CONTROL KNOB Due to crossfeeding between fuel tanks, the tanks should be re- topped after each refueling to assure maximum capacity. Figure 7-6. Fuel System (Standard and Long Range) CESSNA MODEL 152 SECTION 7 AIRPLANE & SYSTEMS DESCRIPTIONS tanks (one in each wing), a fuel shutoff valve, fuel strainer, manual primer, and carburetor. Refer to figure 7-5 for fuel quantity data for both systems. Fuel flows by gravity from the two wing tanks to a fuel shutoff valve. With the valve in the ON position, fuel flows through a strainer to the carburetor. From the carburetor, mixed fuel and air flows to the cylinders through intake manifold tubes. The manual primer draws its fuel from the fuel strainer and injects it into the cylinder intake ports. Fuel system venting is essential to system operation. Blockage of the venting system will result in a decreasing fuel flow and eventual engine stoppage. Venting is accomplished by an interconnecting line from the right fuel tank to the left tank. The left tank is vented overboard through a vent line which is equipped with a check valve, and protrudes from the bottom surface of the left wing near the wing strut attach point. The right fuel tank filler cap is also vented. Fuel quantity is measured by two float-type fuel quantity transmitters (one in each tank) and indicated by two electrically-operated fuel quantity indicators on the lower left portion of the instrument panel. An empty tank is indicated by a red line and the letter E. When an indicator shows an empty tank, approximately .75 gallon remains in either a standard or long range tank as unusable fuel. The indicators cannot be relied upon for accurate readings during skids, slips, or unusual attitudes. The amount of unusable fuel is relatively small due to the dual outlets at each tank. The maximum unusable fuel quantity, as determined from the most critical flight condition, is about 1.5 gallons total. This quantity was not exceeded by any other reasonable flight condition, including pro- longed 30 second full-rudder sideslips in the landing configuration. Takeoffs have not been demonstrated with less than 2 gallons total fuel (1 gallon per tank). The fuel system is equipped with drain valves to provide a means for the examination of fuel in the system for contamination and grade. The system should be examined before the first flight of every day and after each refueling, by using the sampler cup provided to drain fuel from the wing tank sumps, and by utilizing the fuel strainer drain under an access panel on the right side of the engine cowling. The fuel tanks should be filled after each flight to prevent condensation. When the airplane is equipped with long range tanks, it may be serviced to a reduced fuel capacity to permit heavier cabin loadings. This is accomplished by filling each tank to the bottom of the indicator on the fuel filler neck. When filled to this level, the tank contains 13 gallons (12.25 usable in all flight conditions). 7-20 7-21 SECTION 7 AIRPLANE & SYSTEMS DESCRIPTIONS BRAKE SYSTEM CESSNA MODEL 152 CESSNA SECTION 7 MODEL 152 AIRPLANE & SYSTEMS DESCRIPTIONS The airplane has a single-disc, hydraulically-actuated brake on each main landing gear wheel. Each brake is connected, by a hydraulic line, to a master cylinder attached to each of the pilot's rudder pedals. The brakes are operated by applying pressure to the top of either the left (pilot's) or right (copilot's) set of rudder pedals, which are interconnected. When the airplane is parked, both main wheel brakes may be set by utilizing the parking brake which is operated by a knob on the lower left side of the instrument panel. For maximum brake life, keep the brake system properly maintained, and minimize brake usage during taxi operations and landings. Some of the symptoms of impending brake failure are: gradual decrease in braking action after brake application, noisy or dragging brakes, soft or spongy pedals, and excessive travel and weak braking action. If any of these symptoms appear, the brake system is in need of immediate attention. If, during taxi or landing roll, braking action de- creases, let up on the pedals and then re-apply the brakes with heavy pressure. If the brakes become spongy or pedal travel increases, pumping the pedals should build braking pressure. If one brake becomes weak or fails, use the other brake sparingly while using opposite rudder, as required, to offset the good brake. REGULATOR OVER- VOLTAGE SENSOR G CLOCK OIL PRESSURE SWITCH MASTER SWITCH OVER-VOLTAGE WARNING LIGHT TO FUEL QUANTITY INDICATORS ALTERNATOR FUEL IND ALTERNATOR FIELD CIRCUIT BREAKER TO FLASHING BEACON TO PITOT HEAT BCN PITOT STROBE LTS. ALT AMMETER STARTER 11 B ט כ 0 LDG LTS. FLAP TO STROBE LIGHTS TO CIGAR LIGHTER (WITH FUSE AND CIRCUIT BREAKER) TO LANDING AND TAXI LIGHTS TO IGNITION SWITCH TO WING FLAP SYSTEM TO INSTRUMENT, RADIO, AND COMPASS LIGHTS TO OIL TEMPERATURE GAGE INST LTS. TO TURN COORDINATOR FLIGHT HOUR RECORDER STARTER CONTACTOR ELECTRICAL SYSTEM Electrical energy (see figure 7-7) is supplied by a 28-volt, direct- current system powered by an engine-driven, 60-amp alternator and a 24- volt, 14-amp hour battery (or 17-amp hour battery, if installed) located on the right forward side of the firewall. Power is supplied through a single bus bar; a master switch controls this power to all circuits, except the engine ignition system, clock, or flight hour recorder (if installed). The flight hour recorder receives power through activation of an oil pressure switch whenever the engine is operating, and the clock is supplied with current at all times. All avionics equipment should be turned off prior to starting the engine or using an external power source to prevent harmful transient voltages from damaging the transistors in this equipment. MASTER SWITCH The master switch is a split-rocker type switch labeled MASTER, and is ON in the up position and OFF in the down position. The right half of the switch, labeled BAT, controls all electrical power to the airplane. The left half, labeled ALT, controls the alternator. BATTERY 7-22 CODE BATTERY CONTACTOR GROUND SERVICE PLUG RECEPTACLE IGNITION SWITCH BAR NAV DOME TO AUDIO MUTING RELAY TO CONTROL WHEEL MAP LIGHT TO NAVIGATION LIGHTS TO DOME LIGHT ΤΟ WING FLAP TO RADIO CIRCUIT BREAKER RADIO 1 TO RADIO RADIO 2 RADIO 3 TO RADIO OR TRANSPONDER AND ENCODING ALTIMETER TO RADIO RADIO 4 R 0 CIRCUIT BREAKER (AUTO-RESET) CIRCUIT BREAKER (PUSH-TO-RESET) FUSE DIODE RESISTOR CAPACITOR (NOISE FILTER] MAGNETOS Figure 7-7. Electrical System 7-23 SECTION 7 AIRPLANE & SYSTEMS DESCRIPTIONS CESSNA MODEL 152 CESSNA MODEL 152 SECTION 7 AIRPLANE & SYSTEMS DESCRIPTIONS Normally, both sides of the master switch should be used simultane- ously; however, the BAT side of the switch could be turned ON separately to check equipment while on the ground. The ALT side of the switch, when placed in the OFF position, removes the alternator from the electrical system. With this switch in the OFF position, the entire electrical load is placed on the battery. Continued operation with the alternator switch in the OFF position will reduce battery power low enough to open the battery contactor, remove power from the alternator field, and prevent alternator restart. AMMETER The ammeter indicates the flow of current, in amperes, from the alternator to the battery or from the battery to the airplane electrical system. When the engine is operating and the master switch is turned on, the ammeter indicates the charging rate applied to the battery. In the event the alternator is not functioning or the electrical load exceeds the output of the alternator, the ammeter indicates the battery discharge rate. OVER-VOLTAGE SENSOR AND WARNING LIGHT The airplane is equipped with an automatic over-voltage protection system consisting of an over-voltage sensor behind the instrument panel and a red warning light, labeled HIGH VOLTAGE, under the ammeter. In the event an over-voltage condition occurs, the over-voltage sensor automatically removes alternator field current and shuts down the alter- nator. The red warning light will then turn on, indicating to the pilot that the alternator is not operating and the battery is supplying all electrical power. The over-voltage sensor may be reset by turning the master switch off and back on again. If the warning light does not illuminate, normal alternator charging has resumed; however, if the light does illuminate again, a malfunction has occurred, and the flight should be terminated as soon as practical. The warning light may be tested by momentarily turning off the ALT portion of the master switch and leaving the BAT portion turned on. CIRCUIT BREAKERS AND FUSES Most of the electrical circuits in the airplane are protected by "push-to- reset" circuit breakers mounted under the engine controls on the instru- ment panel. The cigar lighter is equipped with a manually-reset type circuit breaker located on the back of the lighter and a fuse behind the instrument panel. The control wheel map light (if installed) is protected by the NAV/DOME circuit breaker, and a fuse behind the instrument panel. Electrical circuits which are not protected by circuit breakers are the battery contactor closing (external power) circuit, clock circuit, and flight hour recorder circuit. These circuits are protected by fuses mounted adjacent to the battery. GROUND SERVICE PLUG RECEPTACLE A ground service plug receptacle may be installed to permit the use of an external power source for cold weather starting and during lengthy maintenance work on the electrical and electronic equipment. The recepta- cle is located behind a door on the left side of the fuselage near the aft edge of the cowling. Just before connecting an external power source (generator type or battery cart), the master switch should be turned ON. This is especially important since it will enable the battery to absorb transient voltages which otherwise might damage the transistors in the electronic equip- ment. The battery and external power circuits have been designed to com- pletely eliminate the need to "jumper" across the battery contactor to close it for charging a completely "dead" battery. A special fused circuit in the external power system supplies the needed "jumper" across the contacts so that with a "dead" battery and an external power source applied, turning the master switch ON will close the battery contactor. LIGHTING SYSTEMS EXTERIOR LIGHTING Conventional navigation lights are located on the wing tips and top of the rudder, a single landing light is installed in the cowl nose cap, and a flashing beacon is mounted on top of the vertical fin. Additional lighting is available and includes dual landing/taxi lights in the cowl nose cap and a strobe light on each wing tip. All exterior lights are controlled by rocker type switches on the lower left side of the instrument panel. The switches are ON in the up position and OFF in the down position. The flashing beacon should not be used when flying through clouds or overcast; the flashing light reflected from water droplets or particles in the atmosphere, particularly at night, can produce vertigo and loss of orienta- tion. The high intensity strobe lights will enhance anti-collision protection. 7-24 7-25 SECTION 7 AIRPLANE & SYSTEMS DESCRIPTIONS CESSNA MODEL 152 However, the lights should be turned off when taxiing in the vicinity of other airplanes, or during night flight through clouds, fog or haze. INTERIOR LIGHTING Instrument and control panel lighting is provided by flood lighting and integral lighting. Two concentric rheostat control knobs on the lower left side of the instrument panel, labeled PANEL LT, and RADIO LT, control the intensity of both flood and integral lighting. Instrument and control panel flood lighting consists of a single red flood light in the forward part of the overhead console. To use the flood lighting, rotate the PANEL LT rheostat control knob clockwise to the desired intensity. The radio equipment and magnetic compass have integral lighting. The light intensity of all integral lighting is controlled by the RADIO LT rheostat control knob. A cabin dome light is located in the aft part of the overhead console, and is operated by a switch on the lower portion of the instrument panel. To turn the light on, place the switch in the ON position. A control wheel map light is available and is mounted on the bottom of the pilot's control wheel. The light illuminates the lower portion of the cabin just forward of the pilot and is helpful when checking maps and other flight data during night operations. To operate the light, first turn on the NAV LIGHTS switch; then adjust the map light's intensity with the knurled disk type rheostat control located at the bottom of the control wheel. The most probable cause of a light failure is a burned out bulb; however, in the event any of the lighting systems fail to illuminate when turned on, check the appropriate circuit breaker. If the circuit breaker has opened (white button popped out), and there is no obvious indication of a short circuit (smoke or odor), turn off the light switch of the affected lights, reset the breaker, and turn the switch on again. If the breaker opens again, do not reset it. CESSNA MODEL 152 SECTION 7 AIRPLANE & SYSTEMS DESCRIPTIONS EXHAUST MUFFLER SHROUD HEATER VALVE DEFROSTER OUTLET ADJUSTABLE VENTILATOR VENTILATING AIR DOOR CABIN HEAT CONTROL CABIN AIR CONTROL ADJUSTABLE VENTILATOR CODE RAM AIR FLOW VENTILATING AIR HEATED AIR BLENDED AIR CABIN HEATING, VENTILATING AND DEFROSTING SYSTEM The temperature and volume of airflow into the cabin can be regulated to any degree desired by manipulation of the push-pull CABIN HT and MECHANICAL CONNECTION Figure 7-8. Cabin Heating, Ventilating, and Defrosting System 7-26 7-27 SECTION 7 AIRPLANE & SYSTEMS DESCRIPTIONS CABIN AIR control knobs (see figure 7-8). CESSNA MODEL 152 CESSNA MODEL 152 Heated fresh air and outside air are blended in a cabin manifold just aft of the firewall by adjustment of the heat and air controls; this air is then vented into the cabin from outlets in the cabin manifold near the pilot's and passenger's feet. Windshield defrost air is also supplied by a duct leading from the manifold. Full ventilation air may be obtained by utilization of the adjustable ventilators near the upper left and right corners of the windshield, and by pulling the CABIN AIR control knob out. The CABIN HT control knob must be pushed full in. PITOT-STATIC SYSTEM AND INSTRUMENTS The pitot-static system supplies ram air pressure to the airspeed indicator and static pressure to the airspeed indicator, rate-of-climb indicator and altimeter. The system is composed of either an unheated or heated pitot tube mounted on the lower surface of the left wing, an external static port on the lower left side of the forward fuselage, and the associated plumbing necessary to connect the instruments to the sources. The heated pitot system consists of a heating element in the pitot tube, a rocker-type switch labeled PITOT HT on the lower left side of the instrument panel, a 15-amp circuit breaker under the engine controls on the instrument panel, and associated wiring. When the pitot heat switch is turned on, the element in the pitot tube is heated electrically to maintain proper operation in possible icing conditions. Pitot heat should be used only as required. AIRSPEED INDICATOR The airspeed indicator is calibrated in knots and miles per hour. Limitation and range markings include the white arc (35 to 85 knots), green arc (40 to 111 knots), yellow arc (111 to 149 knots), and a red line (149 knots). If a true airspeed indicator is installed, it is equipped with a rotatable ring which works in conjunction with the airspeed indicator dial in a manner similar to the operation of a flight computer. To operate the indicator, first rotate the ring until pressure altitude is aligned with outside air temperature in degrees Fahrenheit. Pressure altitude should not be confused with indicated altitude. To obtain pressure altitude, momentarily set the barometric scale on the altimeter to 29.92 and read pressure altitude on the altimeter. Be sure to return the altimeter baromet- SECTION 7 AIRPLANE & SYSTEMS DESCRIPTIONS ric scale to the original barometric setting after pressure altitude has been obtained. Having set the ring to correct for altitude and temperature, read the true airspeed shown on the rotatable ring by the indicator pointer. For best accuracy, the indicated airspeed should be corrected to calibrated airspeed by referring to the Airspeed Calibration chart in Section 5. Knowing the calibrated airspeed, read true airspeed on the ring opposite the calibrated airspeed. RATE-OF-CLIMB INDICATOR The rate-of-climb indicator depicts airplane rate of climb or descent in feet per minute. The pointer is actuated by atmospheric pressure changes resulting from changes of altitude as supplied by the static source. ALTIMETER Airplane altitude is depicted by a barometric type altimeter. A knob near the lower left portion of the indicator provides adjustment of the instrument's barometric scale to the current altimeter setting. VACUUM SYSTEM AND INSTRUMENTS An engine-driven vacuum system (see figure 7-9) is available and provides the suction necessary to operate the attitude indicator and directional indicator. The system consists of a vacuum pump mounted on the engine, a vacuum relief valve and vacuum system air filter on the aft side of the firewall below the instrument panel, and instruments (including a suction gage) on the left side of the instrument panel, ATTITUDE INDICATOR An attitude indicator is available and gives a visual indication of flight attitude. Bank attitude is presented by a pointer at the top of the indicator relative to the bank scale which has index marks at 10°, 20°, 30°, 60°, and 90° either side of the center mark. Pitch and roll attitudes are presented by a miniature airplane in relation to the horizon bar. A knob at the bottom of the instrument is provided for in-flight adjustment of the miniature airplane to the horizon bar for a more accurate flight attitude indication. DIRECTIONAL INDICATOR A directional indicator is available and displays airplane heading on a compass card in relation to a fixed simulated airplane image and index. The directional indicator will precess slightly over a period of time. Therefore, the compass card should be set in accordance with the magnetic 7-28 7-29