Pilot's Operating Handbook for Mooney M20B Mark 21

mounted on the lower left section of the front cowling, keeps the oil from getting too warm. Stratoflex hoses, triple-lined for extra safety, feed the oil from the oil reservoir to the cooler, then back to the reservoir. ENGINE FUEL SYSTEM Fuel for the engine is fed to the float-type carburetor by an engine- driven, diaphram-type fuel pump mounted on the accessory section of the engine. The Lycoming 0-360 A-1-A engine is designed for 91-98 octane aviation grade fuel; however 100-130 octane aviation grade fuel -3- 譬 is preferable, if available, because of its lower lead content. WARNING! Under no circumstances should aviation fuel of a lower grade than 91-09 octane be used in this engine. Aviation fuels may be distinguished by their color. Remember that 80 octane is RED; 91 octane is BLUE; 100 octane is GREEN. ENGINE ACCESSORIES The Lycoming 0-360 A-1-A engine is equipped with the following accessories: Generator Starter Magnetos Fuel Pump Carburetor Spark Plug Oil Radiator Battery Vacuum Pump Delco-Remy 50 ampere output Delco-Remy 12 volt type Bendix S-200 (left magneto equipped with retard breaker points) AC Diaphram-type Marvel MA4-5 float-type AC SR-88D Harrison Model APO7AU0603 Rebat R-33, 33 amperes Airborne Mechanism's Dry-Type, Model 113 THE MARK 21 PROPELLER The Mark 21 utilizes a McCauley Constant Speed propeller. The blades have a high-aspect ratio and a diameter of 74 inches. They are constructed of aluminum alloy and are annodized, as well as painted, for protection. Operation of this propeller is completely automatic. Once the desired propeller speed is established by the pilot, the blades automatically change their pitch to maintain a constant engine speed. The hub of the propeller contains a completely sealed, pitch actuating unit. All materials of this unit have been specifically chosen for their resistance to wear and are fully protected against weathering. Grease and oil seals are made of synthetic rubber of high durability. All aluminum alloy parts are annodized. All steel parts are suitably plated. The blade actuating pins are chrome-plated, not only for protection, but -4- to provide low friction and wear-resistant surfaces for better operation. Other steel members are cadmium-plated. PROPELLER OPERATION The McCauley propeller utilized engine oil pressure to change from low to high pitch. The oil comes from the engine lubrication system; how- ever, since the propeller's oil pressure requirements are greater than the engine's, the oil pressure is boosted by a geared pump in the Woodward governor before it is delivered to the propeller. A strong spring, aided by the blade's centrifugal force, changes the pitch of the propeller from high to low pitch. This force is always present in the propeller and is counter-balanced by the oil pressure. THE PROPELLER GOVERNOR The Woodward propeller governor, which is mounted on the accessory section of the engine, controls the speed of the propeller and the engine by decreasing the oil pressure when the RPM is too low. This allows the spring and the centrifugal force to change the propeller pitch so that it takes a smaller "bite" and thus speeds up. The governor increases the oil pressure to the propeller when the RPM is too high. The extra oil pressure overcomes the force of the spring and the centrifugal force and changes the propeller pitch so that it takes a larger "bite" and thus slows down. PRE-FLIGHT INSPECTION Before each flight the propeller blades should be checked for any nicks, cracks, or signs of other damage. NOTE: It is not unusual for the propeller to have a certain amount of end-play. This is a result of manufacturing tolerances in the parts. Small differences at the blade root are magnified many times at the tip. This end-play has no adverse effect on the performance or operation of the propeller. As soon as the propeller begins to rotate, the centrifugal force of the blades seats them positively and rigidly against the bearing. -5- C HUNTING OR SURGING Sometimes it may be noted that the tachometer needle wavers in straight and level flight. If it is excessive, it may be further checked to determine if the problem lies in the propeller governor system or in the tachometer by doing the following: 1. 2. Increase the propeller control to the "high RPM" position. The RPM should go to 2700. Reduce the manifold pressure control until the RPM is below 2700. At this time, the propeller will be in fixed pitch. If the tachometer needle continues to waver, the problem lies in the tachometer and cable system, itself. If the tachometer needle stabi- lizes, then the problem lies in the governor and propeller system. eliminate this condition, have your mechanic purge, or clean the propeller system. То If surging of the propeller occurs during takeoff or climb out, it may be caused by air in the system of foreign matter in the governor passages. If, after the system has been purged, surging persists, the condition may be cured by adjusting the carburetor. THE MARK 21 FUSELAGE THE CABIN SECTION The forward section of the fuselage is composed of a truss-type welded steel frame covered with aluminum skin. A stainless steel fire wall separates the cabin from the engine compartment. Generous use of sound-deadening lead tape and fiber glass soundproofing makes the cabin "whisper quiet. Three sixteenth inch tinted glass on the side windows, and one-fourth inch tinted glass on the front windshield add greater comfort and safety. Fiber glass window frames are painted to harmonize with the decor of the luxurious interior fabrics. Cabin seats are constructed of welded steel frames, and the two front seats recline for greater comfort on long trips. All seats incorporate "no-sag" springs overlaid with poly-foam rubber cushions and covered with expensive and tastefully chosen fabrics for maximum comfort and beauty. The interior styling is by Fred M. Gore, noted industrial designer. -6- The cabin door is stamped from heat-treated aluminum and has a three-way, positive-locking latch, and is tightly sealed so that there are no air leaks. A heavy piano-type hinge is used to secure the door to the fuselage. The three-way latch mechanism has a safety latch, a lock pin, and a latch hook to hold the door positively and securely in place. A heavy, chrome-plated steel door handle actuates the latching mechanism. LUGGAGE COMPARTMENT or out. The extra-large luggage compartment is easily accessible from inside The door is made both air and water tight by a full length piano hinge, rounded corners and rubber mounding. Location of the compart- ment makes the loading and unloading of baggage easy and convenient. THE FUSELAGE TAIL CONE SECTION Aluminum The fuselage tail cone section is of monocoque construction. skin, dipped in zinc-chromate primer for corrosion protection, is riveted to heat-treated aluminum bulkheads to form the tail cone section. Extruded aluminum stringers. add longitudinal strength to the tail cone. An access opening is located on the left side of the tail cone section of the fuselage for easier access to the tail. This greatly facilitates the installation of radio power packs and inspection of the tail cone. A spring-steel tail skid and tie down ring are attached to the lower section of the tail cone rear bulkhead. This is to protect the tail from damage in the event of an extreme nose-high landing and to provide a tie-down ring for parking. Tail empennage attaching hinges are locked to the fuselage tail cone through a reinforced multiple-bulkhead system, which distributes all tail empennage loads into the tail cone structure. These hinges are constructed of heavy, machined metal and are attached to the tail cone by Huck bolts, Hi-Shear rivets, and Hi-Lock fasteners--all proved by extensive use with the military and the airlines to be superior locking devices. THE TAIL TRIM ACTUATING MECHANISM The tail trim actuating mechanism is built into the multiple-bulkhead system, also. A screw-jack, operated by a torque tube running from the pilot's trim wheel to the tail cone rear bulkhead, trims the aircraft by moging the entire tail empennage. A short-coupled, piano-type hinge (the lower tail attaching hinge) absorbs the effects of any unsymmetrical tail loads caused by air gusts, and allows the trim screw-jack to operate completely free of any side loads. The tail-attaching hinges and bolts -7- are reamed to close tolerances and to give the tail empennage free movement without excess end play. All structural members of the tail cone and trim actuating system are specially "Turco-treated" against corrosion. THE MARK 21 WING THE LAMINAR-FLOW WING The Mark 21 uses a laminar-flow wing. This wing reduces drag, improves aerodynamic efficiency over standard airfoils, and yet retains very docile slow-flight and stall characteristics. Through the use of the laminar-flow wing, the Mark 21 has achieved almost unbe- lievable performance for its horsepower. THE MARK 21 WING CONSTRUCTION The Mark 21 wing is all metal and is constructed in one piece, incorpo- rating a single main spar of rugged "Z"-type construction. Every bulkhead in the wing forms a torsion box which distributes the wing loads evenly over the entire wing. The wing skin is attached to the wing utilizing a new "wrap-around" technique that eliminates any skin laps in a span-wise direction, thus contributing to a smoother wing surface. The skin is pre-stretched and is flush-riveted from the leading edge rearward on the wing surface to a point where rivet-head drag is at a minimum. The main spar is constructed in one piece. All spar caps are extruded from 7075 T-6 aluminum alloy and are assembled in such a manner as to form a "Z" cross-section. High-strength fasteners, such as Huck bolts, Hi-shear rivets, and AD rivets insure maximum structural integrety. The wing is built on six assembly jigs and then each assembly is trans- ferred to one wing-final-assembly jig for completion. These jigs are optically leveled and aligned to insure a high degree of uniformity. This results in a truer airfoil, better appearance, and closer tolerance fit of all parts. The wing is attached to the fuselage by thirty-four attaching bolts. Aileron and flap hinges are machined from extrusions. All structural members of the wing are "Turco-treated" against corrosion, and the main spar receives further corrosion protection in the form of a coating of zinc-chromate primer. -8- THE MARK 21 TAIL EMPENNAGE The tail empennage is constructed in the same manner as the wing. Optically aligned jigs insure uniformity and close tolerance fit of all parts. The same "wrap-around" skin construction and use of flush riveting eliminates high-drag skin laps. The rear spars on both the horizontal and vertical stabilizer are made from extrusions, as are all control hinge fittings. A metal gap strip attached to the aft side of the stabilizers effectively stops drag- producing air flow between the empennage and the control surfaces. THE MARK 21's NEW TYPE PAINT All exterior metal parts of the Mark 21 are painted with a new type acrylic-base enamel. This enamel is non-porous and leaves a plastic- like covering over the metal parts. The advantages are: 1. A higher gloss finish. 2. A finish that is easier to maintain, since it requires no waxing. 3. 4. 5. A finish that has greater resistance to oxidation and thus will stand up longer under adverse-weather conditions. A finish that retains its resiliency almost indefinitely, and resists chipping or rain-chaffing. Greater re-sale value of the airplane. THE MARK 21 LANDING GEAR The Mark 21 landing gear is unique in that it is manually retracted by the pilot. Gear-assist springs in the wings, aided by bungee-type springs in the fuselage, make the manual operation of the gear quite simple. New overcenter-lock springs positively force the down-locking mechanism into place when the gear is lowered. -9- ( GEAR CONSTRUCTION Neo- The landing gear is constructed of heavy, chrome-molybdenum tubular steel, heat-treated for greater strength and resistance to wear. prene rubber discs of great resiliency absorb the shock of normal taxiing and landing. The Cleveland wheels are made of magnesium castings and the six-ply tires are made by Goodyear. The main gear has a nine-foot tread, which makes taxiing a simple operation; and because of the wide gear-tread and the aircraft's low center of gravity, taxiing or landing in strong cross-winds presents no problem, even to the novice pilot. The attaching points of the main gear are in metal bushings embedded in a gear-mounting box and attached to the spars. The nose wheel is mounted to the cabin's tutular-steel frame instead of to the engine mount. Tire pressures are as follows: Nose wheel tire Main wheel tires 24 to 30 pounds 24 to 30 pounds THE MARK 21 MISCELLANEOUS INSTALLATIONS THE INSTRUMENT PANEL The instrument panel has been scientifically designed to provide functional location of all flight, radio, and engine instrument groupings. All flight instruments are grouped on a shock-mounted panel directly in front of the pilot. They are located in such a manner as to provide maximum efficiency for the instrument cross-check, a most important item for good IFR flying. The radio panel is located in the center of the instrument panel and has sufficient room for two modern radios. A sub-radio panel is located on the far right side of the panel, should a third radio be desired. All of the engine instruments are grouped on the co-pilot's panel. A brief glance tells the whole story on engine operation, since all the engine instruments are in one location. The electrical panel is divided into two parts: A. The electrical toggle switches, which are lower left side of the pilot's panel. They are (from left to right): -10- 1. The main fuel gauge selector. 2. The electric fuel pump. 3. 4. Space for an optional equipment switch. The pitot heat (if ordered). 5. The rotating beacon (if ordered). 6. The navigation lights. 7. The landing light. B. The breaker switches, or fuses, which are located on the lower right side of the co- pilot's panel, and are covered by a special breaker switch cover. These switches are of the push to re-set type. The push-pull controls are located on the lower right side of the pilot's panel. These operate (from left to right): 1. The parking brakes. 2. The cabin heat. 3. The cold air. 4. The carburetor heat. The carburetor heat control is located just to the left of the throttle for convenience and safety. It has a serrated shaft to reduce "creeping" of the control when partially on. THE MARK 2 1 CONTROLS The ailerons, elevator, and rudder on the Mark 21 are of all-metal construction. They are jig-built, using hinges of machined extrusions. The elevator and rudder incorporate an unusual method of construction. The leading-edge spar of these controls consists of a specially designed extrusion that allows flush attachment of the skin. The control system for the Mark 21 requires very little maintenance and provides superior control-feel because torque tubes, rather than the conventional cable system, are used to actuate the controls. The fact that this control system provides unsurpassed control pressure and response through the elimination of slack in the system, and the fact that it provides a more durable and lower maintenance system, are reasons why the Mark 21 has attained such popularity in such a short period of time. HEIM bearings are used throughout the control system. These bearings are permanently lubricated and require no maintenance. -11- (