Aircraft General Knowledge (Basic Airplane Powerplant) PDF

**[AIRCRAFT GENERAL KNOWLEDGE]** (Basic Airplane Powerplant) **ENGINES** **[Categories:]** 1. 2. **[Types of reciprocating engines:]** 1\. Opposed -- cylinders are arranged directly opposed each other on the crankshaft 2\. Radial -- arranged in circular manner 3\. V type -- v-engine setti...

**[AIRCRAFT GENERAL KNOWLEDGE]** (Basic Airplane Powerplant) **ENGINES** **[Categories:]** 1. 2. **[Types of reciprocating engines:]** 1\. Opposed -- cylinders are arranged directly opposed each other on the crankshaft 2\. Radial -- arranged in circular manner 3\. V type -- v-engine setting 4\. In-line type -- cylinders are lined up in one row **[Parts of a reciprocating (piston) engine:]** 1. 2. 3. 4. 5. **[Engine power cycle or 4-stroke operating cycle:]** \- Continuous energy-creating process 1\. Intake 2\. Compression 3\. Power 4\. Exhaust **[I. INDUCTION SYSTEM]** \- Brings outside air into the engine, mix it with fuel in the proper proportion, and delivers it to the cylinders. **[Engine controls for the induction system:]** 1. 2. **[2 types of induction system:]** 1. **[Indications of carburetor icing:]** 1. 2. \*When carb heat is applied, there will be a drop in rpm, then rpm will increase slowly as ice melts. Then as you turn off the carb heat, rpm will increase some more. 2. **[Intake port]** -- outside air enters the induction system through this port; contains an air filter which inhibits the entry of dust or other foreign objects; found in front of the engine compartment \*Sea-level performance can be obtained at high altitudes using *superchargers/turbochargers*. **[II. IGNITION SYSTEM]** \- Provides the spark that ignites the fuel/air mixture in the cylinder. **[Parts of an ignition system:]** 1\. **Magnetos** - Self-contained engine-driven unit that supplies electrical current to the spark plugs. - - - - 2\. **Spark plugs** -- provides the spark for the fuel/air mixture 3\. **Interconnecting wires** -- connect the ignition switch, magnetos and spark plugs 4\. **Ignition switch** -- controls the operation of the magnetos ***Dual ignition system* --** more efficient combustion for improved engine power and performance; safety factor **[2 kinds of abnormal combustion:]** \(1) **Detonation** -- uncontrolled explosive ignition of the fuel/air mixture within the combustion chamber; causes excessive temperature and pressure which can lead to failure of piston, cylinder, or valves; can cause overheating, roughness or loss power [Causes:] a\. Using low grade fuel b\. Fuel/air mixture too lean c\. Overheated mixture temperature d\. High cylinder head temperature e\. Opening throttle abruptly when engine is at low speed \(2) **Pre-ignition** -- uncontrolled firing of the fuel/air charge before the spark ignition; can be caused by detonation; caused by residual *hotspots* in the cylinder (*carbon deposits*) \*To decrease engine temperature: reduce power; increase airspeed; enrich the mixture. **[III. FUEL SYSTEM]** \- The function of the fuel system is to store fuel and deliver it to the carburetor (or fuel injection system) in adequate quantities at the proper pressure. **[2 types:]** \(i) **Gravity-fed system** -- fuel flows by gravity from the tanks to the engine \(ii) **Fuel pump system** -- usually found in low-wing airplanes where fuel tanks maybe located below the engine; have a fuel pressure gauge a. b. **Primer** - manually operated pump; pumps fuel directly into the intake system prior to start; useful in cold weather when fuel in the carburetor is difficult to vaporize. **Fuel tanks** -- most commonly located in the wings; contains a *vent* which allows air pressure to remain the same as that outside the tank; contains an *overflow drain* which prevents rupture due to fuel expansion **Fuel quantity gauges** -- shows the amount of fuel in the tanks **Fuel selector valve** -- allows you to select fuel from various tanks (OFF, BOTH, LEFT, RIGHT) **\*[Vapor lock]** -- air enters the system **[Refueling]** -- major hazard is possible combustion by a spark which causes the fuel to ignite; most probable cause is the static electricity that discharges between refueling equipment and the airplane (should use ground wire) \*Use only higher grade fuel if fuel being used is not available. \*Fuel must be checked for water and other contaminants. \*Fuel planning and good management are vital tasks. \*Fill tanks after last flight of the day to prevent moisture from condensing by eliminating air. **[Fuel grade] [Color]** 80 Red (mogas) 100LL Blue (avgas) 100 Green (unleaded) Turbine fuel or Jet A-1 Colorless **[IV. LUBRICATION SYTEM]** [**Engine oil** ] -- ***lubricates*** engine's moving parts; ***cools*** the engine by reducing friction; provides a ***seal*** between cylinder walls and pistons, thus improving engine efficiency; during circulation, ***carries away contaminants*** which are removed as the oil passes through the filter. (Oil **lubricates**, **cools**, **seals** and **clears**.) **[Types of system (for reciprocating engines):]** \(1) **Dry sump system** -- oil is contained in a separate tank and circulated through the engine by pumps \(2) **Wet sump system** -- oil is carried in a sump which is an integral part of the engine. \***Dipstick** -- used to measure oil \***Oil pressure gauge** -- measures the oil supplied to the engine in P.S.I. \***Oil temperature gauge** -- measures the temperature of oil **[V. COOLING SYSTEM]** \- Designed to keep the engine temperatures within those limits designed by the manufacturer. Outside air enters the engine compartment through an inlet behind the propeller hub. Baffles direct it to the hottest parts of the engine, primarily the cylinders. **[Cowl flaps]** -- regulates temperature within the engine compartment; fixed or adjustable; the deciding factor for the pilot in where to position the cowl flaps is the *cylinder head temperature* (CHT) **[VI. ELECTRICAL SYSTEM]** \- A typical modern light airplane has a *direct current* (DC) electrical system. The electric current is produced by an **alternator** when the engine is running, or from a **battery** or external power source when the engine is not running. **[Alternator]** -- main source of electrical power; recharges the battery **[Battery]** -- provides emergency electrical power and electrical power for engine start **[Bus bar]** -- main conductor and the distribution center in the electrical system **[Ammeter/Load meter]** -- measures the electrical current (amps) flowing into or out of the battery **[Master switch]** -- controls all of the airplane's electrical system (but it does not control the ignition system which gets electrical power directly from the engine-driven magneto) **[Fuses/Circuit breakers]** -- protects electrical equipment from current overload **[VII. EXHAUST SYSTEM]** \- The burnt gases leave the engine cylinders and are carried out to the atmosphere via the exhaust system. (It is important that there is no leakage of exhaust gas into the cabin because it contains *carbon monoxide*.) \- Provides heat for the cabin and carburetor. **[VIII. PROPELLERS]** \- Rotating airfoil that produces thrust. **[2 types:]** \(1) **Fixed-pitch propeller** -- blades have fixed angle a\. [Climb propeller] -- low blade angles (high performance on takeoff and climb) b\. [Cruise propeller] -- high blade angles (high-speed cruise, high altitude flight; more "bite") \(2) **Constant-speed propeller** -- blade angle can be controlled [2 controls:] a\. Throttle control - for *manifold pressure* (manifold pressure gauge) b\. Propeller control -- for *RPM* (tachometer) **\*Propeller governor** -- senses air pressure and automatically changes the blade angle **Low pitch** -- small blade angle; slow flight **High pitch** -- large blade angle; fast flight **[Geometric pitch]** -- how far the propeller would *theoretically* advance in one revolution **[Effective pitch]** -- how far the propeller *actually* advances through the air in one revolution **Propeller efficiency** -- ratio of *thrust horsepower* (propeller) to *brake horsepower* (engine) \***Typical propeller efficiency** -- between 50% and 85% lift-to-weight, depending on slippage