Term
| How many throws are there in the crankshaft of a 6 cyl. engine? |
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Definition
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Term
| What kind of connecting rod arrangment is used in a radial engine |
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Definition
| Master rod connects to a single throw of the crankshaft with a piston. All of the other pistons are connected to the master rod with link rods. |
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Term
| What material are most piston rings made of? |
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Definition
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Term
| What is the reason for using hydralic valve lifters in acft engine? |
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Definition
| lifters eliminate all clearance out of the valve operating mechanicsm. reduces wear of the valve components. |
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Term
| at what speed does the camshaft turn, relative to crankshaft? |
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Definition
| Turns at one/half of the crankshaft speed. |
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Term
| on what stroke is the piston of a receiprocating engine when the intake valve beings to open? |
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Definition
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Term
| on what stroke is the piston of a recip egine when the exhiast valve begins to open? |
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Definition
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Term
| what is meant by cam-ground piston? |
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Definition
| piston not perfectly round. allows for temperature variations. |
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Term
| what is meany by a full-floating wrist pin? |
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Definition
| wrist pin not clamped in either piston or connecting rod. prevent from scoring cylunder walls by soft metal plugs on the ends. |
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Term
| what is purpose of valve overlap in recip egine? |
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Definition
| assist in scavenging and exhuast/intake process. |
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Term
| what type of piston rings are installed on the pistons of an recip engine? |
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Definition
| compressions rings, oil control rings, and oil wiper rings. |
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Term
| why are some exhaust valves partially filled with metallic sodium? |
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Definition
| material melts at operating temp and transfer heat from valve head to the cylinder head. |
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Term
| what causes detonation in aircraft engine? |
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Definition
| excessive heat/pressure in cylinder causes mixture to reach critical condition. mixture then explodes rather then burns. |
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Term
| what is a compression check important for determinding the conidition of an recip engine. |
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Definition
| determines the seals between the piston rings and the clyinder walls, and seats between intake/exhaust valves. |
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Term
| what are the two basic sections of a turbine engine? |
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Definition
| hot section and cold section |
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Term
| what are the two basic types of compressioes that are used in turbines? |
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Definition
| axial flow and centrifugal |
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Term
| what is the purpose of the stators in an axial flow compressor? |
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Definition
| converts some velocity into pressure energy and changes direction to guide into rotors. |
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Term
| what are three types of combustors used on aircraft turbine engines? |
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Definition
| can-type, annunlar, can-annular |
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Term
| what is the main purpose of the turbine nozzle in an aircraft turbine engine? |
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Definition
| directs hot gases as they leave the combustors so they turn the turbine wheel most efficently |
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Term
| what is meant by a turbofan engine? |
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Definition
| an axial flow turbine engine in which the first stage of compressor blades are lengthened, so they can send air around the outside of the hot portion of the engine. |
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Term
| why is it important that a turbojet engine be allowed to cool before shut down? |
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Definition
| allow enough time for the blades to compressor before the shround aroudn the engine contracts around the tubrine wheel. |
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Term
| where is water injected unto a turbine engine for cooling purposes |
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Definition
| into the compressor inlet and into the engine diffuser case |
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Term
| what is function of the interconnect tubes between the cans of a turbine engine that uses can-type combustors? |
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Definition
| allows the flame to travel from the cans that have ignitors to all of the other cans during engine start. |
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Term
| what are two types of thrust reverses that are used on turbojet engines? |
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Definition
| mechanic blockage type and aerodynamic blockage types |
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Term
| in what publication can a mechanic find the operating limitations for an aircraft engine? |
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Definition
| type certificate date sheet for the engine. |
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Term
| what are two types of compression checks that can be performed on an recip engine? |
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Definition
| a differential compression check and a direct compression check. |
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Term
| what items are checked in a hot section inspection of a turbine? |
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Definition
| combustion section is checked for cracks or distortion. the turbine wheel and the exhuast for cracks, warping, overheating. |
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Term
| in what units is the tachometer for a recip engine calibrated? |
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Definition
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Term
| what two materials are the thermocouples made that are used in a turbine engine exhaust system? |
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Definition
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Term
| what kind of mechanism is normally used to measure oil pressure in a recip engine? |
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Definition
| a bourbon tube mechanism. |
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Term
| does the tachometer of a heared reciprocating engine indicate the speed of the crankshaft or of the propeller shaft? |
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Definition
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Term
| does a break in a continouse loop fire detection system keep the system from detecing a fire? |
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Definition
| No, will show a fault at testing but still show a fire. |
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Term
| does the pressure type contrinue element detect overheat condition as well as a fire? |
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Definition
| yes, a high temp in a small section, or a lower temp over the entire sensor will release enough gas to close the swith and warn of a fire. |
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Term
| how can a mechanic determine the state of charge of the HRD bottles of fire extinguisher agent? |
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Definition
| a pressure gauge on the bottle shows the pressure of the contents of the bottle. |
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Term
| Which type of fire detection system operates on the rate of temperature rise? |
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Definition
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Term
| why are the wires in certain electrical installation twisted together? |
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Definition
| magnetic field caused by the current is minimized. |
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Term
| what is minimum separation that is allowed between a wire bundle and a fluid line that carries combustible or oxygen? |
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Definition
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|
Term
| significance of the color of the solder less connectors used on electrial wires? |
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Definition
| color indicates the size of the wire the connector will fit. |
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Term
| what is used as the rectifier to produce direct current in a DC generator? |
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Definition
| brushes and a commutator. |
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Term
| how does a vibrator type voltage regulator control the output voltage of a DC generator? |
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Definition
| contacts vibrate open and closed depending on over limit voltage, putting the resistor in and out of the filed of circuit to control the amount of voltage the generator produces. |
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Term
| what is meant by paralleling the generaots of a twin engine aircraft? |
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Definition
| adjusting voltage of the gnerators so they will share the electrical load equally. |
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Term
| what is used to maintain a constant frequency of the AC that is produced by an AC alternator drive by an aircraft turbine? |
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Definition
| a hydraulic constant speed drive until between the engine and the alternator. IDG |
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Term
| when removing a battery from an aircarft, which connection should be removed first? |
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Definition
| the ground connection must be disconnected first and connected last. |
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Term
| what is a starter-generator that is used with many smaller gas turbine engines? |
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Definition
| serves as a starter for the engine. then once started it will shift and work as a compound wound generator. |
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Term
| what is meant by the viscoity of engine lubricating oil? |
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Definition
| resistance of the oil to flow |
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Term
| what is meant by a west sump system? |
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Definition
| lubrication sustem in which the oil is carried inside of engine itself. |
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Term
| what is meant by dry sump system? |
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Definition
| oil is carried in a tank that is not part of the engine |
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Term
| how is oil temp controlled in an aircraft recip engine? |
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Definition
| hot oil is directed through core of the oil cooler but cold is directed around the outside of the core so it will not be further cooled. |
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Term
| what is the purpose of pil dilution in a recip engine? |
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Definition
| when very cold weather is anticipated, gasoline is mixed in to the oil before shut down. makes oil viscocity lower for easier starting. gasoline is then evaporated during run. |
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Term
| what is the puirpose of slude plugs in the cranksshaft of a recip engine? |
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Definition
| trap sludge that is in the oil and hold it until the engine is disassemble for overhaul |
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Term
| what kid of oil is used in most turbojet engines? |
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Definition
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Term
| where are the last chance oil filters located in a turbojet engine? |
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Definition
| inside the engine, just ahead of the nozzles that spray oil onto the bearings. |
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Term
| what is the function of the oil control rings on the piston of an aircraft recip engine. |
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Definition
| maintain proper quanity of oil between piston and cylinder wall. |
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Term
| what is meant by a spectometric oil analysys? |
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Definition
| sample of oil is taken and sent to a lab. A single sample is meaningless. series of samples taken at regular intervals to measure the change in the amounts of these metals. |
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Term
| what is the main advantage of a magneto ignition system over a bettery ignition system for an aircraft recip engine? |
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Definition
| magneto has own source of electrical energy and its not dependant upon the battery. |
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Term
| what is function of the capaciotr in a magneto? |
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Definition
| the capacitor minimizes arcing at the breaker points |
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Term
| what is the significance of the numbers of the distributor of an aircraft magneto? |
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Definition
| sparking order of the magneto, not the firing order |
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Term
| what happens in a magneto ignition system when the ignition siwth is placed in the off position? |
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Definition
| primary circuit is connected to ground |
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Term
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Definition
| spark plugs jump around , lack of isolation/compression |
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Term
| what is meant by the reach of a spark plug? |
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Definition
| length of the threads on the spark plug that screw into the cylinder head. |
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Term
| what is the difference between a hot spark plug and cold spark? |
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Definition
| a hot spark plug, has a long path for the heat to travel. a cold spark plug, the heat has a shorter distacne to travel. |
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Term
| What is checked when a magneto is internally timed? |
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Definition
| adjusting breaker points so they will open at the instant the instant the magnet is in its e-gap position. and distributor rotor is in the position to direct high voltage to cylinder #1. |
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Term
| what is the purpose of a venier coupling used on some aircraft magneto drives? |
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Definition
| located between engine and magneto drive. allows the magneto to engine timing to be varied in increments of less then one degree. |
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Term
| why is it important that the spark plugs be kept in numbered holes in a tray when they are removed from an engine? |
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Definition
| spark plugs tell a good deal about the internal conidition of the cylinders from which they are taken. helps determine overheating/detonation |
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Term
| what is meant by the e-gap in magneto timing? |
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Definition
| position of rotating magent when the primary current flowing in the magneto coil is the greatest. breaker points open during the e-gap and flows to secondary. |
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Term
| what is the function of an impluse coupling? |
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Definition
| spring driven coupling. When the engine is being started, coupling hold the winding unitl pistion passes and release the magney and spins it fast to produce a hot and late spark. |
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Term
| what are the two types of ignition systems used in turbine engines? |
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Definition
| high voltage and low boltage systems. |
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Term
| what malfunction in the ignition system would cause an aircraft recip engine to continue to run after the ignition switch is placed in the off position. |
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Definition
| open in the circuit. not grounding magneto. |
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Term
| what is meant by a duplex nozzle in a turbine engine, fuel metering system? |
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Definition
| two fuel discharge passages. main passage is primary, additional fuel is sent through secondary passage. |
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Term
| what is the function of a float carburator? |
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Definition
| to measure airflow through the engine indction system and dispense approriate amount of gasoline into airflow. also provide vaporized fuel at time of ignition |
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Term
| does the fuel-air mixture provided by a fload carbutrator becomer richer or leaner when carbutrator heat is applied. |
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Definition
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Term
| what are two pruposes of the manifold valve (or flow divider) in the fuel injection system of a horizaontally opoposed acft. |
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Definition
| constant discharge fuel pressue for idling, provides positive shutoff for the fuel when shutting down. |
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Term
| what are two basic types of fuel controls for airracft turbine negines? |
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Definition
| hydropnematic and electro-hydromechanica. |
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Term
| what two things are adjusted when adjusting the idling of a recip engine? |
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Definition
| the throttle stop ot get idle RPM, and idle mixtrue control to get smoothest operation |
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Term
| what is the significane of the letters that are stamped on the flats of a fuel injection nozle. |
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Definition
| letters designate the relative isze of the orifice in the injector nozzle. the lower the letter the smaller the orifice. |
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Term
| in what position is the mixure control placed for starting an engine that is equipped with a pressure carburator. |
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Definition
| in the idle cut off. engine is started with fuel from the primer system. |
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Term
| why is an aircraft recip engine killed by placing the mixture control in the cutoff position, rather than by using the magnesto switch. |
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Definition
| shutting off the fuel to the cylder allows only air to the clynders and preventing left over fuel in the system. |
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Term
| where is the fuel from a continous-flow fuel injection system discahrged, under which valve? |
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Definition
| discharged at the injector nozzles screwed into the cylinder head near the intake valves. |
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|
Term
| what engine parameters are senesed by the fuel control unit of a turbine engine? |
|
Definition
| engine RPM, inlet air pressue, compressors dischange pressure, combustion pressure, inlet are temp. |
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|
Term
| when does the acceleration system operate on a aircraft carburator? |
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Definition
| when the throttle is suddenly opened. |
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|
Term
| what kind of boost pump is used in most aircraft fuel systems? |
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Definition
| electrically operated centrifugal pumps |
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|
Term
| where does an engine drive fuel pump direct the excess fuel from its pressure relief valve? |
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Definition
| back to the inlet side of the pump. |
|
|
Term
| why do some turbine engine fuel systems incorporate a fuel heater? |
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Definition
| the fuel heater keeps the fuel warm enough that any water the precipirates out of the fuel will not freeze on filters. |
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|
Term
| where does carbutrator ice normally form in a carburator? |
|
Definition
| in the throat of the carburator, on and around the throttle valve. |
|
|
Term
| what is used to drive most of the xternal superchargers used on modern reciprocating engines? |
|
Definition
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|
Term
| what controls the speed of a turbochragres compressor |
|
Definition
| controlled by the position of the waster gate. |
|
|
Term
| what kind of inlet duct is often used on a turbine powered helicopters? |
|
Definition
| a bell mouthed inlet duct |
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|
Term
| what is usually installed in a large recip. engine between the turbosupercharger and the carburator? |
|
Definition
| an intercooler. this is an air-to-air heat exchanger. |
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|
Term
| how does an engine air inlet vortex destroyer help prevent foreign object damage to the engine? |
|
Definition
| high velocity stream of compressor bleed air, blown out in front of the engine to break up vortices, that form in front during high power. |
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|
Term
| What is meant by pressure cooling of an aircraft engine? |
|
Definition
| air cooling in which air is forced to flow though baffles and cylnder fins by a pressure difference on the engine. |
|
|
Term
| what is used in a helicopter to incrase the amount of cooling air that flows over the engine cylinder? |
|
Definition
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|
Term
| what should be the position of the cowl flaps on a reciporating engine when it is run on the ground? |
|
Definition
| they should be wide open when operating the engine on the ground. |
|
|
Term
| what is the function of blast tubes that are installed in a pressure cooling system of a recip engine? |
|
Definition
| these blast tubes direct cooling air to the magnetos and the generator. |
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|
Term
| of what material are most recip engine exhuast components made? |
|
Definition
| corrosion-resistant steel. |
|
|
Term
| how is the speed of a tubocharged controlled? |
|
Definition
| by the position of the waste gate in the exhaust pipe. |
|
|
Term
| what would be the effect on engine performance of an internal failure of a muffler? |
|
Definition
| incase the exhuast back pressure and cause a loss of engine power |
|
|
Term
| how does a noise supressor rduce the amount of noise produced by a turbojet engine? |
|
Definition
| breaks up low frequencey vibrations and converts them to high frequency. high frequency are dissipated by the air more easily. |
|
|
Term
| Should an adjustable-putch propellor be in high pitch or in low pitch for takeoff? |
|
Definition
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|
Term
| what is done to cause a hydromatic propeller to feather? |
|
Definition
| high pressure oil is directed into the propeller though the governor. |
|
|
Term
| what is done to cuase a McCauley propller to feather? |
|
Definition
| oil is allowed to drain out of the propeller |
|
|
Term
| do the counterweights on a propeller tend to move the blased toward the high pitch or toward lower pitch. |
|
Definition
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|
Term
| when making a magneto check on a enginer quipeed with a constant speed proppler, should the propleer be in the low pitch of high pitch? |
|
Definition
|
|
Term
| what is adjusted inside the governor for a constant speed propeller to change the speed at which the proppler is operating |
|
Definition
| compression of the speeder rings. |
|
|
Term
| is the flat surface of the properller blade the face of the back of the blade |
|
Definition
|
|
Term
| what keeps a McCauley feathering propeller from feathering when the engine is shutdown on the ground? |
|
Definition
| spring loaded latch prevents movement during ground operation. unlatched in the air to allow movemebt. |
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