(AD) Aviation Machinist Mate Week 2 Practice questions and Answers Latest

(AD) Aviation Machinist Mate Week 2 Practice questions and Answers Latest Electricity - The physical phenomena arising from the existence and interaction of an electrical charge Voltage / Electromotive Force (EMF) - The amount of force being applied to a circuit to produce an electron flow Amperage / Current Flow - The quantity of electricity flowing through the circuit Resistance - The opposition to the flow of electrons offered by a device or material Ohms - The measurement of resistance to current flow Watt - The measurement of electrical work done Forms of Electricity - Static and Dynamic Static Electricity - (1) Electricity at rest (2) Begins with a build up of either a positive or negative electron charge. If two negative charges or two positive charges are brought close together, the objects that hold that charge repel each other. If a positive charge is brought within close proximity of a negative charge, the two objects attract each other (3) Static electricity is produced by friction and is not easily measured nor is it controllable or usable Dynamic Electricity - A practical form of current flow that is used in everyday life. This form of electricity is easily produced, measured, and controlled Methods of Producing Dynamic Electricity - Mechanical, Chemical, Thermal, and Pressure Mechanical - Produced by rotating a magnetic field through another magnetic field Ex: A Grass Cutter Chemical - Produced by surrounding two or metallic plates with a chemical electrolyte Ex: A Battery Thermal - Produced by joining two dissimilar metals and applying heat Ex: Thermocouple Pressure - Produced by applying pressure to quartz, which will produce an electron flow Ex: A Watch Types of Electricity - AC and DC Direct Current (DC) - Current that is a steady flow in one direction only. It is produced mechanically by a DC generator, or chemically by a battery Ex: A Flashlight Alternating Current (AC) - Current flow that reverses direction at specific intervals, defined as Hertz / Cycles. It is produced mechanically by an AC generator Ex: A TV Screen Electrical Test Equipment - Multimeter Multimeter Test Leads - Red lead = Positive and Black lead = Negative Multimeter Digital Display Features - Power Up, Overload Indication (OL), and Low Battery Indicator Power Up - All segments appear while the instrument performs a self-test. At the end of the test, meter will chirp once indicating that it is ready for use Overload Indication (OL) - Indicates input is too large to display Low Battery Indicator - Appears when approximately 100 hours of life remain. If left on, the meter will go to standby mode after one hour to save the battery Systems / Components of the Engine Electrical System - Engine Speed Indicating System, Engine Temperature Indicating System, Fuel Flow Indicating System, Oil Pressure Indicating System and Engine Fire Detection System Engine Speed Indicating System's Components - Tachometer (RPM) Indicator and Tachometer Generator Tachometer (RPM) Indicator - Indicates engine compressor rotor RPM in percent. It is located in the flight station / cockpit Tachometer generator - (1) Mounted and splined to the accessory gearbox (2) Creates an electrical reference signal that represents the rotational speed of the engine compressor (3) The reference signal is transmitted to the tachometer (RPM) indicator and is read as percent of compressor RPM Engine Temperature Indicating System's Components - Thermocouple Assembly and Engine Temperature Indicator Thermocouple Assembly - Constructed of two dissimilar metals, Alumel and Chromel, which, when heated, will create a small voltage that is directly proportional to the engine exhaust temperature Ex: Using heat excites the energy from the metals and creates that small voltage that sends it to the Indicator Engine Temperature Indicator - Displays temperature in degrees Celsius or Fahrenheit Fuel Flow Indicating System's Components - Fuel Flow Transmitter, and Fuel Flow Indicator Fuel Flow Transmitter - (1) Mounted on the engine (2) The transmitter provides an electrical signal that is directly proportional to the mass rate of fuel flow and transmits the signal to the flight station / cockpit Fuel Flow Indicator - Displays the signal as fuel flow in pounds-per-hour (PPH) Oil Pressure Indicating System's Components - Oil Pressure Transmitter and Oil Pressure Indicator Oil Pressure Transmitter - (1) Mounted on the engine (2) Sends a proportional electrical signal to the flight station / cockpit Oil Pressure Indicator - Displays oil pressure in pounds-per-square-inch (PSI) Engine Fire Detection System's Components - Fire Detection Element and Fire Warning Light Fire Detection Element - Senses an overheat condition or fire and transmits a signal to the flight station / cockpit Fire Warning Light - (1) Receives its signal from the fire detection element to illuminate the flight station / cockpit (2) When the temperature in the engine cavity reaches an overheat condition, the sensors will provide a signal, allowing a small current to flow, which is transmitted to illuminate the fire warning light Engine Starting System's Purpose - Provides initial rotation to accelerate the engine to the point where ignition can be accomplished and sustained Engine Ignition System's Type - High Energy Capacitor Discharge: Spark must be constant under varying conditions Engine Ignition System Components - Input Leads, Transformer (Exciter), Ignitor Leads, and Ignitor Plugs Input Leads - Delivers input power from the aircraft electrical system, or from an external power source, to the transformer