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In what position should the crankshaft be when a magneto is being timed to the engine?
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What is the purpose of a cold cylinder check?
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Engines
| Question | Answer |
|---|---|
| In what position should the crankshaft be when a magneto is being timed to the engine? | The piston in cylinder no. 1 should be in the correct position for ignition to occur. This is normally about 30° before top center on the compression stroke. |
| What is the purpose of a cold cylinder check? | A cold cylinder check determines which cylinder is not firing. Run the engine for a few minutes at the speed, and on the magneto, at which it runs roughest. Shut it down and feel the exhaust stack near the cylinder head. The cylinder with the stack that i |
| What is checked on engine runup to determine the operational condition of the engine? | Idling RPM and manifold pressure, engine acceleration, maximum static RPM andmanifold pressure, magneto drop, ignition switch safety check, propeller pitch change, propeller feathering, oil pressure, fuel pressure, and fuel flow. |
| How can you determine the firing order of an 18-cylinder radial engine? | Begin with cylinder 1, add 11 and subtract 7, whichever will keep the numbers between 1 and 18. 1-12-5-16-9-2-13-6-17-10-3-14-7-18-11-4-15-8. |
| What are two main causes of a cylinder having low compression? | Piston rings not seating or broken, and valves not seating or burned. |
| What is a hydraulic lock in an aircraft engine? | Oil has drained past the piston rings and filled the combustion chamber of cylindersthat are below the center line of the engine, If the crankshaft is turned over with this oil in the cylinder it will lock, and there is a probability that the piston, cy |
| How is a hydraulic lock removed from an aircraft engine? | Remove a spark plug from the locked cylinder and drain all of the oil out. Clean the spark plug and replace it. |
| What is a low-tension ignition system? | It is an ignition system using a magneto with a brush-type distributor and a coil that has no secondary wiring. Low voltage is directed from the magneto to a transformer mounted on the cylinder head. Here the low voltage is boosted to a high voltage and i |
| What is a floating cam ring on a large radial engine? | It is a cam ring that rides on a shelf-type bearing with a large amount of clearance between the bearhg and the ring. When adjusting the valves on an engine with a floating cam ring, the pressure of the valve springs on the opposite side of the engine mus |
| Why is valve clearance adjusted on radial engines, but not on most horizontally opposed engines? | Most horizontally opposed engines have hydraulic valve lifters that keep all of the clearance out of the valve train. Radial engines have solid lifters. |
| Why are both the hot and cold valve clearances given for most radial engines? | The hot clearance is given for valve timing purposes. The timing is adjusted with the valves in cylinder number one, set with the hot clearance. When the timing is set, all of the valves are adjusted to their cold clearance. |
| What must be inspected to determine the airworthiness of an engine installation? | The propeller, lubrication system, ignition system, fuel metering system, cooling system, and the exhaust system. |
| What checks should be made to determine the proper operation of a reciprocating engine installation? | Idle RPM and mixture, static RPM, propeller pitch change operation, magneto check, ignition switch safety check, and carburetor heat check. |
| Where can you find the correct grade of fuel and amount of engine lubricating oil for an aircraft engine? | In the Type Certificate Data Sheets for the aircraft. |
| What are the basic steps in troubleshooting an engine installation? | a. Know how the system should operate.b. Obseive how the system is operating.c. Divide the system to find the trouble.d. Look for the obvious problems first. |
| Where do you find the procedures to follow when correcting a defective condition in an aircraft engine? | In the engine maintenance manual. |
| Where do you find instructions for removing an engine from an aircraft? | In the aircraft maintenance manuaL |
| What must normally be done to.a nose-wheel airplane before removing an engine? | The tall of the airplane must be supported. |
| What should be done to the cylinders to protect them from rust and corrosion when preparing the engine for long-time storage? | Spray a preservative oil inside the cylinders and replace the spark plugs with desiccant plugs. |
| What should be used to cover the ends of fuel and oil lines that have been disconnected from the engine? | The correct plugs or caps. Never cover the end of a line with tape. |
| What is meant by a QEC engine assembly? | An engine that has been prepared for a quick engine change. The engine is on its mount and all of the accessories are installed. A minimum of time is required to change engines. All that is needed is for the controls, wiring, and fluid lines to be connect |
| What is meant by rigging the engine controls so they have some “cushion”? | The control on the engine component must contact its stop before the control handle in the cockpit reaches its stop. This causes the control handle to spring back a slight amount when it is moved to the extent of its travel. |
| What are two ways of pre-oiling an engine? | a. Before the spark plugs are installed and after the oil tank or sump is filled, turn the engine over with the starter until oil runs out of the fitting to which the oil pressure gage connects.b. Use a pre-oiler tank. Air pressure forces oil through al |
| What is meant by a hot-section inspection? | An inspection of the hot section of a turbine engine. The hot section includes the combustors, the turbine, and the exhaust system. |
| What is meant by on-condition maintenance of a turbine engine? | The monitoring of the engine performance at regular intervals and determining when maintenance is required based on certain operating parameters specified by the engine manufacturer. |
| What checks of a turbine engine are necessary to verify preflight condition? | • Inspection of the cowling and all air inlet areas and attachment of the engine to the airframe.• Inspection of the inlet guide vanes and the first stage of the compressor or fan blades.• Check for unusual noise when the compressor is rotated.• Ins |
| What is meant by trimming a turbine engine? | Adjusting the fuel control so the engine develops the correct idle and trim speed RPM. |
| What type of equipment should be used to determine that a turbine engine is performing up to the standards specified by the engine manufacturer? | A JetCal Analyzer/Trimmer has all of the instrumentation and cables to determine the EGT EPR, and the other parameters specified by the engine manufacturer. |
| Where can you find the model of magneto that is approved for an engine specified by the examiner? | In the Type Certificate Data Sheet for the engine. |
| What is a Supplemental Type Certificate? | An approval issued by the FAA for a modification to a type-certificated airframe, engine or component. |
| What paperwork is necessary for the installation of a magneto that was not approved for an engine when it was certificated, but is approved for the engine when installed according to an STC? | A form FAA 337 must be completed stating that the installation was done in accordance with the specific STC. |
| What are three types of flow-indicating systems used for turbine engines? | Vane-type flow meters, synchronous mass-type flow meters, and electronic motorless mass flow meters. |
| What do mass flow systems measure? | The mass of the flow. This is affected by the density of the fuel which is in turn affected by the fuel temperature. |
| In what units is an electronic motorless mass flow meter system calibrated? | Pounds per hour of fuel flow. |
| What is indicated in a turbine engine if the fuel flow for all conditions is high? | If there are other instrument abnormalities, there are possibly damaged turbine components. |
| Who is authorized to repair a fuel flow indicating system? | The components can be repaired only by an FAA approved repair station certificated for the particular instruments. |
| Where can you find the electrical power requirements for a fuel flow indicating system? | In the aircraft maintenance manual. |
| Where in the fuel system is the fuel flow transmitter located? | Bet ween the fuel control and the fuel nozzles. |
| What kind of indicating system is used to measure oil temperature in a small, single-engine, general aviation airplane? | A sealed system in which a bulb, partially filled with a highly volatile liquid, is installed inside the oil strainer. The bulb is connected to a pressure gage by a copper tube. The pressure of the gas above the liquid is proportional to the temperature o |
| What type of instrument system is used for measuring cylinder-head temperature and exhaust gas temperature? | A thermocouple system. |
| What kind of electrical instrument system is used for measuring oil temperature? | A ratiometer-type system. |
| What should a thermocouple cylinder-head temperature indicator read when the engine is cold? | The same as the outside air temperature gage. |
| What is critical in the installation of the thermocouple leads for a cylinder-head temperature indicator, the length of the leads or their resistance? | The resistance is critical, it must have the resistance specified on the indicator. This is usually 2 or 8 ohms. |
| What should a ratiometer temperature indicator read when the electrical power is off? | The pointer should be off scale on the low side. |
| What kind of tachometer is used on most small single-engine airplanes? | A magnetic drag tachometer that is similar to an automobile speedometer. |
| What would likely cause the pointer of a magnetic drag tachometer to oscillate? | Either a dry cable connecting the indicator to the engine, or a kink in the cable housing. |
| Is it permissible for a mechanic with an airframe and powerplant rating to replace the tachometer cable for a magnetic drag tachometer? | Yes, this does not constitute a repair to an instrument. |
| What kind of tachometer is used on most large multi-engine airplanes? | A three-phase AC electric tachometer. |
| What is measured to indicate the engine RPM with a three-phase AC electric tachometer? | The frequency of the AC the tachometer generator produces. |
| What kind of indicator mechanism is used to measure oil pressure? | A Bourdon tube. |
| What kind of indicator mechanism is used to measure manifoldpressure? | A differential bellows. |
| What should a manifold pressure gage read when the engine is not operating? | The existing barometric pressure as indicated on the altimeter barometric scale when the altimeter pointers are set to the surveyed field elevation. |
| What type of fitting is used to connect an oil pressure gage to the engine? | A fitting with a restrictor that smoothes out the pulsations and prevents a break in the indicator line, ca using a serious loss of engine oil. |
| What is used to fill the line between a fuel pressure gage and the fuel metering system? | A light oil such as kerosine. |
| What could cause a fuel pressure gage to fluctuate? | The loss of the light oil in the line between the gage and the engine. |
| Is a certificated mechanic with an airframe and powerplant rating allowed to zero the pointers on a fuel pressure gage? | No, a mechanic is not allowed to make any repairs or alterations to an aircraft instrument. |
| How does a ratiometer-type oil temperature gage measure the temperature of the oil? | A ratiometer measures the resistance of the temperature bulb. The indicator is call-bra ted in degrees Fahrenheit or Celsius rather than in ohms. |
| What is the range of pressure needed for a fuel pressure gage used with a float carburetor? | Normally from 1 .to 25 psL |
| What are four types of engine fire detection systems? | The rmoswitch system, thermocouple system, thermistor-type continuous-loop system, pneumatic-type continuous-loop system. |
| Which type of fire detection system operates on the principle of the rate of temperature rise? | The thermocouple system. |
| Why must the reference junction in a thermocouple fire detection system be thermally insulated? | This is a rate-of-temperature-rise system. The reference junction must be insulated so its temperature will not rise as quickly as that of the measuring junctions if a fire should occur. |
| How do you check a thermocouple fire detection system for operation? | Press the test switch. This heats the test thermocouple enough for it to close the sensitive relay, which in turn closes the slave relay and activates the fire warning light and bell. |
| What would likely cause a false fire alarm in a thermistor-type continuous-loop system? | A kinked or pinched continuous-loop element. |
| If there is a break in a single-wire continuous-loop fire detector element, and the system tests bad, will it indicate the presence of a fire? | Yes, even though it tests bad, it will still indicate the presence of a fire. |
| How is a pneumatic-type continuous-loop fire detection system checked for operation? | When the test switch is closed, low-voltage AC flows through the tube that encloses the sensitive element. This current heats the element enough for it to release sufficient gas to activate the alarm switch. |
| What maintenance is allowed on a continuous-loop fire detection system? | Inspect and replace as needed the continuous-loop element, the controller, and the fire, warning bell and/or light. |
| What happens in a jet transport airplane when the fire-pull T-handle for anengine is pulled? | The engine fuel shutoff valve is closed.The generator field relay is tripped.The compressor bleed air valve is closed.The anti-ice valve is closed.The hydraulic supply shutoff valve is closed.The hydraullc pump low-pressure warning lights are tu |
| What is used as a fire extinguishing agent in some older aircraft? | Carbon dioxide (C02). |
| What fire extinguishing agent is used in the high-rate discharge bottles installed in a jet transport aircraft? | Halon 1211 or .1301. |
| How is a high-rate discharge bottle of fire extinguishing agent discharged? | A powder charge is ignited and it blows a cutter through a frangible disk that seals the bottle. |
| What precaution must be taken when checking the electrical circuit for igniting the powder charge in the valve of a high-rate discharge bottle? | The current used to check the integrity of the electric circuit must not be high enough to ignite the powder charge. |
| What is indicated if the red discharge indicator for a fire extinguishing system is blown out? | The system has been discharged by an overheat condition. |
| What is indicated if the yellow discharge indicator for a fire extinguishing system is blown out? | The system has been discharged by actuating the bottle discharge switch. |
| What color and marking is used to idsntify the fluid lines that carry the fire extinguishing agent in an aircraft? | Brown tape with a series of diamonds on it. |
| When should the brushes in a starter motor be replaced? | When they have worn to one half of their original length. |
| How is the direction of rotation of a DC electric motor reversed? | Reverse the polarity of the armature or the field, but not both. |
| What is used as the rectifier to produce direct current in a DC generator? | Brushes and a commutator. |
| What is used as the rectifier to produce direct current in a DC alternator? | Six solid-state diodes. |
| Is a starter motor series-wound or shunt-wound? | Series wound for maximum stalled-rotor torque. |
| What are two ways wires can be attached to the pins in a cannon plug? | a. By soldering the wires into pots on the pins and sockets.I,. By crimping tapered pins onto the wires and inserting the pins into tapered holes in the pins and sockets. |
| Why is stranded wire used rather than solid wire, in most powerplant electrical systems? | Solid wire is likely to break when it is subjected to vibration. |
| What two things must be considered in selection of wire size when making an electrical installation in an aircraft? | The current-carrying capability of the wire, and the voltage drop caused by current flowing through the wire. |
| What must be done to a DC generator, after it has been overhauled, before it can produce electricity? | The field must be flashed to restore residual magnetism to the field frame so it can begin to produce current. |
| Why is it not necessary to flash the field of a DC alternator after it has been overhauled? | An alternator field is excited by battery current and residual voltage is not used to start the alternator producing current. |
| What is used to protect a wire bundle from chafing where it passes through a hole in a bulkhead or frame? | A grommet around the edges of the hole. |
| How are electrical wires protected where they pass through an area of high temperature? | Wires passing through these areas are insulated with high-temperature insulation, and the wires are enclosed in some type of protective conduit. |
| What is the minimum separation allowed between a wire bundle and a fluid line that carries combustible fluid or oxygen? | Six inches. |
| Which aircraft electrical circuit does not normally contain a fuse or circuit breaker? | The starter motor circuit. |
| What is a starter-generator? | A single, engine-mounted component that serves as a starter for starting the turbineengine. When the engine is running, the circuitry automatically shifts so it acts as acompound-wound generator. |
| When should aircraft wiring be installed in a conduit? | When the wiring passes through an area in the aircraft where open wiring could likely be damaged, such as through a wheel welL |
| What is meant by a trip-free circuit breaker? | A circuit breaker that opens a circuit any time an excessive amount of current flows, regardless of the position of the circuit breaker’s operating handle. |
| Which way should the toggle of a switch that controls the propeller pitch move to place the propeller in low pitch (high RPM)? | Forward. |
| Why are protective covers placed over some switches in an aircraft electrical circuit? | To prevent the switch from being inadvertently actuated. |
| What is straight mineral oil? | It is the lubricating oil as obtained by fractional distillation of crude oil. It does not have any additives. |
| What is ashless dispersant (AD) oil? | A mineral lubricating oil containing additives that disperse the contaminants throughout the oil so they will not clump and clog oil passages. There are no ash-forming additives in AD oil. |
| What is synthetic oil? | A lubricating oil that is made by chemically changing the nature of an oil base to give it the heeded characteristics. Synthetic oil is the primary oil for turbine engines. |
| Is automotive oil suitable for use in aircraft engines? | No, automotive and aviation oils are formulated for entirely different operating conditions. |
| What is meant by a multiviscosity oil? | It is a lubricating oil with a viscosity index improver that increases the viscosity of the oil when it is hot and decreases the viscosity when it is cold. |
| What are six functions of the oil in an aircraft engine? | a. Reduces friction.b. Seals and cushions.c. Removes heat.d. Cleans inside the engine.e. Protects against corrosion.f. Performs hydraulic action. |
| Where can you find the grade of engine oil specified for a particular aircraftl | In the Aircraft Flight Manual or the Pilot’s Operating Handbook for the aircraft. |
| What components in a reciprocating-engine lubrication system must be inspected on a 100-hour or annual inspection? | The oil sump or tank, the oil stra her screen, the oil filter, the oil cooler and the temperature control valve, the oil pressure and temperature gages and any transmitters associated with them, and the entire engine for hdication of oil leaks. |
| What two instruments show the condition of a reciprocating-engine lubrication system? | Oil pressure and oil temperature gages. |
| What must be done to an oil filter when it is removed from the engine? | It should be cut open and the pleated element examhed to determine the type and amount of contamhant carried by the oil. |
| What is a spectrometric oil analysis program? | A program in which a sample of oil is taken from the enghe at regular intervals and sent to a laboratory, where it is burned in an electric arc. The resulthg light is analyzed for the wavelengths of the elements that are present in the oil sample. Traces |
| What is the purpose of an air-oil separator, or deaerator, in a turbine engine oil tank? | In normal operation, the oil picks up a quantity of air and it is swirled as it enters the deaerator. The swirling action releases the air from the oil, and the air is used to pressurize the oil tank. |
| What type of oil quantity indicator is used in most aircraft engines? | A dipstick that measures the quantity of oil in the tank or sump. |
| When should the engine oil quantity be checked on a turbine engine? | As soon as practical after the engine is shut down. |
| Where is the oil temperature measured on a reciprocating engine? | Usually at the oil pressure screen before the oil goes into the engine passages. |
| How is oil pressure regulated in an aircraft engine? | A pressure-relief valve senses the desired pressure and sends all of the oil that caused excessive pressure back into the engine sump. |
| Why do engine manufacturers recommend that engine lubricating oil be changed at specific intervals? | The oil picks up contaminants and carries them through the engine where they can cause wear. The oil also becomes acidic and causes corrosion in the engine. |
| What is the purpose of the restricted orifice in the line between the oil pressure gage and the engine? | The restricted fitting helps dampen any pulsations in the oil pressure caused by the pump. |
| What is a hot-tank lubrication system for a turbojet engine? | A lubrication system in which the oil cooler is in the pressure subsystem and the scavenged oil is not cooled before it is returned to the tank. |
| What is a cold-tank lubrication system for a turbojet engine? | A lubrication system in which the oil cooler is in the scavenge subsystem, and the scavenged oil is cooled before it is returned to the tank. |
| What is the main advantage of a magneto ignition system over a battery ignition system for an aircraft reciprocating engine? | A magneto has its own source of electrical energy, and is not dependent upon the battery. |
| What is the function of the capacitor in a magneto? | The capacitor minimizes arcing at the breaker points, and it speeds up the collapse of the primary current as the breaker points open. |
| What happens in a magneto ignition system when the ignition switch is placed in the Off position? | The primary circuit is connected to ground. |
| What is checked when a magneto is internally timed? | Internally timing a magneto consists of adjusting the breaker points so they will open at the instant the rotating magnet is in its E-gap position, and the distributor rotor is in position to direct the high voltage to cylinder number one. |
| In what position should the ignition switch be placed when using a timing light on the magnetos? | In the Both position. |
| What type of ignition system is used on most turbine engines? | High-intensity, intermittent-duty, capacitor discharge ignition systems. |
| What is the E-gap in magneto timing? | The E-gap angle is the position of the rotating magnet when the primary current flowing in the magneto coil is the greatest. The breaker points open when the rotating magnet is in its E-gap position. |
| What is the function of an impulse coupling? | An impulse coupling is a spring-driven coupling between the magneto and the engine. When the engine is being started, the impulse coupling holds the rotating magnet until the piston passes over its top center position and starts down. The impulse coupling |
| How many igniters are used with most turbine engines? | Two. |
| What are two types of ignition systems used in turbine engines? | High-voltage systems and low-voltage systems. |
| With which type of turbine-engine ignition system is a glow plug igniter used? | A low-voltage system. |
| How is the strength of the magnet in a magneto checked? | The magneto is put on a test stand and rotated at a specified speed. The breaker points are held open and the primary current is measured. The strength of the magnet determines the amount of primary current |
| In what position is the magnet in a magneto, when the greatest change in flux density in the coil core takes place? | It is a few degrees beyond its neutral position. When it is in this position, the breaker points open and the primary current is interrupted. The flux change in the coil core is the greatest. |
| In what position is the magnet in a magneto when the breaker points begin to open? | In its E-gap position, just a few degrees beyond its neutral position. |
| What malfunction in the ignition system would cause an aircraft reciprocating engine to continue to run after the ignition switch is placed in the Off position? | The ignition switch is not grounding the magneto primary circuit. |
| What kind of equipment is used to test an ignition harness for a reciprocating engine? | A high-voltage electrical leakage detector. |
| What is an All-Weather spark plug? | A shielded spark plug that has a recess in the shielding in which a resilient grommet on the ignition lead forms a watertight seal. |
| What is meant by the reach of a spark plug? | The length of the threads on the spark plug that screw into the cylinder head. |
| What is the difference between a hot spark plug and a cold spark plug? | A hot spark plug has a long path for the heat to travel between the nose core insulator and the spark plug shell. In a cold sparkplug, the heat has a shorter distance to travel, and the spark plug operates cooler than a hot spark plug. |
| What is the advantage of fine-wire spark plugs over massive electrode spark plugs? | Fine-wire spark plugs have a firmg end that is more open than that of a massive electrode sparkplug. The open firing end allows the gases that contain lead to be purged from the spark plug so they will not form solid lead contaminates. |
| Why is it important that the spark plugs be kept in numbered holes in a tray when they are removed from an engine? | Spark plugs tell a good deal about the internal condition of the cylinders from which they were taken. By knowing the cylinder from which each spark plug came, the mechanic can take the proper action when a spark plug indicates such conditions as detonati |
| Why is it important that a torque wrench always be used when installing spark- plugs in an aircraft engine? | If the spark plugs are not put in tight enough, there is the possibility of a poor seal; if they are put in too tight, there is danger of cracking the insulation. |
| What kind of gage should be used to measure the electrode gap in aircraft sparkplugs? | A round wire gage. |
| What kind of electric starting system is used on many of the smaller turbine engines? | A starter-generator. |
| What happens when the start switch for a turbine engine with a starter- generator is placed in the START position? | a. Current flows into the starter relay which closes and actuates the ignition exciter.b. Current flows through the series motor coils of the starter generator and rotates the engine until it starts. |
| What happens when the start switch for a turbine engine with a starter- generator is placed in the RUN position? | a. The starter relay opens, shutting off current to the ignition exciter and the motor windings in the starter-generator.b. The generator field relay is closed connecting the voltage regulator to the starter- generator.c. The output of the generator f |
| What is indicated if the starter relay chatters rather than locks in, when the start switch is placed in the START position? | The battery voltage is too low to supply enough current to hold the relay engaged. |
| Why are air-turbine starters superior to electric starters for large turbine engines? | They are light weight for the torque they produce. |
| Where does an air-turbine starter get its air for starting the engines on a jet transport airplane? | From an APU, GPU, or from a running engine. |
| What is the purpose of the shear section in an air-turbine drive shaft? | If the ratchet mechanism fails to release and the engine drives the starter to a speed higher than its design speed, the shear section will break and disconnect the starter from the engine. |
| What prevents too high an air pressure from overspeeding an air-turbine starter? | The air shutoff and regulating valve. |
| Where does an air-turbine starter get it lubricating oil? | It has a self-contained lubrication system with the oil held in the starter housing. |
| What device in an air-turbine starter warns a technician if there are any metal chips or particlesin the oil? | Magnetic chip detectors warn of any metal contamination in the oil. |
| What parameters are normally sensed by a turbine-engine fuel control? | a. Power lever angle.b. Compressor inlet total temperature.c. Compressor RPM.d. Burner pressure. |
| What is meant by trimming a turbine engine? | Adjusting the fuel control for the proper specific gravity of the fuel and for the proper idle and full throttle RPM. |
| What are two types of electronic fuel controls for turbine engines? | Supervisory Electronic Engine Control and Full-Authority Digital Electronic ControL |
| What is a FADEC? | A Full-Authority Digital Electronic Control (FADEC) is a high-precision digital electronic fuel control that functions during all engine operations. It includes the Electronic Engine Control (EEC) and functions with the Flight Management Computer (FMC) to |
| Does a turbine engine controlled by a FADEC require manual trimming? | No, this is done by the FADEC. |
| When should a turbine engine be retrimmed? | Any time there is a decrease in engine thrust, and after any maintenance that the manufacturer specifies as requiring retrimming. |
| Are the instruments installed in an aircraft suitable for use when trimming a turbine engine? | No, a special analyzer/trimmer such as a JetCal should be used. |
| What specifications are used to trim a turbine engine? | The data plate specifications for the specific engine. This data was obtained when the engine was calibrated in the manufacturer’s test cell. |
| Where should ambient temperature be measured when trimming a turbine engine? | In a shaded area as near the engine inlet as is practical. |
| What is meant by a compensated fuel pump? | It is a fuel pump that senses the ambient air pressure and maintains the fuel pressure a specific amount above this air pressure. |
| What would likely cause a reciprocating engine equipped with a float carburetor to hesitate momentarily when the throttle is rapidly advanced from idle to full power? | A malfunctioning accelerator pump. |
| Why do aircraft fuel metering systems for reciprocating engines have mixture controls? | The air density decreases as the aircraft ascends, causing the mixture to become richer. The mixture control allows the fuel to be decreased to maintain a fuel-air mixture ratio that produces the desired power. |
| What are the two types of fuel injection systems used on modern reciprocating aircraft engines? | Teledyne Continental (TCM) system and Precision Airmotive (Bendix) system. |
| What is used in the TCM fuel injection system to control the amount of fuel sent to the nozzles? | The engine speed determines the injector pump output pressure. The relief valve determines the fuel for low-speed operation, and the adjustable orifice determines the fuel for high-speed operation. |
| What is used in the Precision Airmotive system to control the amount of fuel sent to the nozzles? | The mass of the air entering the engine acts on an air diaphragm that controls a servo ball valve in the line between the regulator and the flow divider. |
| Where are the fuel strainers normally located in an aircraft fuel system? | Finger strainers are located in the tank outlet, the main strainer, located at the lowest point in the fuel system, and strainers in the carburetor or fuel injection system. |
| What are two types of fuel heaters used in a jet transport aircraft? | Air-to-fuel and oil-to-fuel heat exchangers. |
| What kind of fuel boost pumps are normally installed inside the fuel tanks? | Centrifugal pumps. |
| What two things are adjusted when setting the idling conditions on a float carburetor? | a. Idling RPM by adjusting the throttle stop.b. Idling mixture by adjusting idle needle valve. |
| What are three functions of the boost pump in the tank of a jet transportaircraft? | a. To pressurize the fuel in the line between the tank and the engine-driven pump.b. To transfer fuel from one tank to another to balance the fuel load.c. To pump fuel from the tank into the dump chute when fuel is being dumped. |
| Why does ice form in the throat of a float carburetor? | When liquid fuel evaporates it absorbs enough heat from the air to cause moisture to condense out and freeze. |
| Does the application of carburetor heat cause the fuel-air mixture to become richéror leaner? | The less dense, heated air draws the same amount of fuel from the carburetor as cold air, therefore the mixture becomes richer. |
| What happens to engine RPM when carburetor heat is applied? | The RPM drops. |
| Why should the use of carburetor heat be limited when operating an engine with the aircraft on the ground? | The air that flows into the engine when carburetor heat is applied is not filtered. |
| Why is a fuel-injected reciprocating engine not as prone to icing as an engine equipped with a float carburetor? | In a fuel-injected engine, the liquid fuel evaporates in the intake valve chamber of the hot cylinder head. |
| How is ice prevented from forming on the nose cowl, nose dome and inlet guide vanes of a turbine engine? | Hot compressor bleed air flows through passages in these components to keep them too warm for ice to form. |
| What does a fuel-injected engine have that prevents the loss of induction air, if the air inlet filter should become covered with ice? | An alternate air valve allows warm air from inside the engine cowling to flow into the fuel metering system. |
| What would be the effect on engine operation of an air leak in the intake pipe for one cylinder? | That cylinder would run lean and detonation could occur. |
| Why is it very important that the induction air filters be kept clean and replaced as often as the manufacturer recommends? | Clogged air filters can restrict the air entering the engine. |
| What is meant by pressure cooling of an air-cooled engine? | Ram air on one side of the engine is forced by a series of baffles to flow through the fins on the cylinders to a low-pressure area on the other side of the engine. |
| What must be inspected on the cooling system of an air-cooled engine? | Allot the baffles and air seals must be in place and in good condition. |
| Why should an air-cooled engine not be run up to high power without the cowling installed? | The engine depends on the cowling to force air through the cylinder fins to remove the excess heat. |
| Why do some air-cooled engine installations have cowl flaps? | Cowl flaps produce a low pressure on one side of the engine to pull air through the cooling fins on the cylinders. |
| Where can you find what is the maximum amount of cylinder fin area that can be removed in order to clean out a damaged area? | In the engine overhaul manual. |
| What document describes the proper use of cowl flaps on an air-cooled engine? | The Pilot’s Operating Handbook. |
| How does a leak appear in an engine exhaust system? | It normally looks like a gray or black feather-shaped streak coming from a crack or from a location where components are not in perfect alignment. |
| How can you check an exhaust system for leaks? | Pressurize the exhaust system with the discharge from a vacuum cleaner and wipe a soap solution over all joints and suspect areas. A leak will cause bubbles to form. |
| How do the components in the exhaust system of a turbocharged engine allow for expansion and contraction due to heat, and at the same time prevent leakage? | Bellows and ball joints prevent leakage while allowing contraction and expansion. |
| What type of damage is most common in the exhaust system of a reciprocating engine? | Cracks caused by expansion and contraction. |
| Should a turbocharged engine be started with the waste gate open or closed? | Open, so as much exhaust as possible will bypass the turbine. |
| Why are thrust reversers not normally used when the airplane is moving below approximately 60 knots? | There is a danger of recirculathg the exhaust gases, and of the engine ingesting foreign objects stirred up by the high-velocity gases. |
| What is a mechanical-blockage thrust reverser? | A thrust reverser that sildes a pair of scoop-shaped doors aft and opens them so they block the rearward flow of gases and deflect the gases forward. |
| How does a cascade-type thrust reverser operate? | A portion of the fan cowl moves rearward, and a series of blocker doors deflect the fan discharge air through fan cascades that direct the discharge air forward. At the same time, blocker doors shut off the flow of gases from the core engine and deflect i |
| What is meant by a slave engine with regard to propeller synchronization? | This is the engine in a multi-en gine airplane whose RPMs follow those set on the master engine. |
| What does the pilot do to change the RPM of an engine equipped with a constant-speed propeller when it is operating within the constant-speed range? | The pilot moves the propeller pitch control. This changes the compression on the speeder spring inside the governor which moves the pilot valve. The pilot valve directs oil into or out of the propeller to change the pitch of the blades. The change in pitc |
| How is ice prevented from forming on propeller blades? | A chemical anti-icing system is used. A mixture of isopropyl alcohol and ethylene glycol is pumped into a slinger ring on the back of the propeller hub. From there centrifugal force slings it out along the blades. Ice cannot form on the resulting slick su |
| How is ice removed from propeller blades? | An electrothermal deicing system is used. Electrical heating elements are embedded in rubber boots that are bonded to the leading edges of the blades. Low-voltage DC flows from the propeller deicer control through brushes and sllp rings to the heating ele |
| How can you determine that the electrically heated deicér boots on the propeller blades are working as they should? | Observe the loadmeter or ammeter to see if the proper current is flowing, and follow the sequence of boot heating by feeling with your hands to see which one is heating. The boots should all have a similar heat rise in the same length of time. |
| How are propellers on a twin-engine airplane synchronized? | The propeller governor of the master engine is set to the desired RPM. A signal from the master engine governor is sent to the control box which sends a signal to a stepping motor. This motor adjusts the propeller governor and fuel control of the slave en |
| Where do you find a list of the lubricants that are approved for use in a constant-speed propeller? | In the maintenance manual for the propeller. |
| Who, or what facility, is authorized to perform major repairs to a propeller? | An FAA-approved propeller repair station that is authorized for the specific propeller. |
| What checks and maintenance is a mechanic with a powerplant rating allowedto make on a propeller? | • Check the track of the propeller blades.• Remove, small nicks and scratches from the blades.Check the dynamic balance of a propeller.• Lubricate the propeller. |
| What adjustment can a mechanic with a powerplant rating make to a propeller governor? | Adjust the maximum RPM stop. |
| Why do some aircraft engines have a critical range of operation? | The engine and propeller combination have a resonant frequency problem in which excessive vibration can occur in a certain range of RPM. The tachometer for an aircraft with this limitation is marked with a red arc. When it is necessaiy to pass through thi |
| What is the difference between a controllable propeller and a constant-speed propeller? | Basically, it is the control system. A controllable-pitch propeller uses a manually operated oil valve to control the pitch, and a constant-speed propeller uses a governor to control the valve. |
| Does centrifugal twisting moment on a propeller blade tend to move the blades toward high pitch or toward low pitch? | Toward low pitch. |
| Do the counterweights on a propeller tend to move the blades toward high pitch or toward low pitch? | Toward high pitch. |
| What is adjusted inside the governor for a constant-speed propeller to change the speed at which the propeller is operating? | The compression of the speeder spring. |
| What is the function of the accumulator used with some McCauley feathering propellers? | The accumulator stores oil under pressure when the engine is operating normally. This oil is used to help the propeller blades move toward low pitch when the propeller is being unfeathered. |
| What is meant by the beta range of operation of a turboprop propeller? | This is the mode of ground operation, and it includes starting, taxiing, and ground reverse operation. |
| What is meant by the alpha range of operation of a turboprop propeller? | This is the in-flight mode of operation from takeoff to landing. |
| What is done to cause a McCauley propeller to feather? | Oil is allowed to drain out of the propeller. |
| What keeps a McCauley feathering propeller from feathering when the engine is shutdown on the ground? | A spring-loaded latch mechanism prevents the blades moving into the feather position when the engine is shut down on the ground. In the air, aerodynamic forces keep the propeller rotating fast enough that centrifugal force holds the blades unlatched so th |
| Should an adjustable-pitch propeller be in high pitch or in low pitch for takeoff? | In low pitch. |
| What is done to cause a Hydromatic propeller to feather? | High-pressure engine oil is directed into the propeller through the governor. |
| When making a magneto check on an engine equipped with a constant-speed propeller, should the propeller control be in the low-pitch or the high-pitch position? | It should be in the low-pitch, high RPM position. |
| What can be done to prevent the front cone from bottoming when installing a propeller on a splined shaft? | Install a spacer behind the rear cone to move the propeller forward on the shaft. |
| What is the function of the snap ring inside the hub of a propeller that is mounted on a tapered or splined shaft? | The snap ring allows the propeller to be pulled off of the shaft when the retaining nut is backed off. |
| Why is a propeller indexed to the engine crankshaft? | The relationship between the propeller and the engine crankshaft is chosen to produce the minimum vibration. |
| What instrument is used to measure the blade angle of a propeller? | A universal propeller protractor. |
| Where is the propeller protractor placed to measure the propeller blade angle? | At a distance from the center of the propeller hub. This distance is specified in the propeller maintenance manual in terms of propeller blade stations. |
| What is the extent of the repairs a mechanic with a powerplant rating can make to a propeller? | Only minor repairs or minor alterations. |
| Where can examples of acceptable repairs to aluminum alloy propeller blades be found? | In AC 43.13- lB. Chapter 8, Section 4. |
| Is it permissible to cold straighten a damaged aluminum alloy propeller blade to facilitate shipping it to a repair station? | No, this could cause hidden damage that may render the blade nonrepairable. |
| What would be the classification of maintenance for shortening a propeller. blade? | Major repair. |
| May transverse cracks in a metal propeller blade be repaired? | No, a transverse crack of any size is reason for rejecting the blade. |
| What damage to an aluminum alloy propeller blade can be repaired by a mechanic holding a powerplant rating? | Small roughness, nicks, and scratches in the leading edge of the blades. |
| How are small nicks removed from the leading edge of a propeller blade? | File them out with a fine file or stone, leaving a smooth contour. |
| Who is allowed to reduce the diameter of a type certificated propeller? | An FAA-certificated propeller repair station with approval for the particular propeller. |
| How can you determine that a surface scratch in an aluminum alloy propeller blade is not actually a crack? | Clean the damage out to a saucer-shaped depression and spray the area with a dyepenetrant liquid. Allow it time to seep into a crack if one is present, then wipe all of the liquid off the surface. Spray the area with a developer. If the damage is actually |
| Where are most APU5 located in modern jet transport aircraft? | In the tall cone of the fuselage. |
| What is the function of an APU? | An APU provides electric power and compressed air when the math engines are not operating. |
| What are two sources of compressed air from an APU? | From bleed air from the APU turbine compressor, or from a load compressor driven by a free turbine in the engine. |
| Where in maintenance information based on the ATA-100 system would you find instructions for inspecting and servicing the engine of an airborne APU? | In section 4920. |
| How is most of the troubleshooting done for a modern APU? | By the fault codes generated by the FADEC. |
| What ensures that an APU will not be shut down while it is too hot? | The APU fuel control incorporates an automatic time-delay feature that closes thebleed air valve to remove most of the load and reduce the APU temperature before it is shut down. |
| What prevents the APU exceeding its safe operating limits when the bleed air valve is wide open? | The FADEC monitors the load and regulates the fuel going to the APU to prevent it from exceeding its safe limits. |
| What document would you use to find the safety procedures to follow when replacing an igniter plug in an APU engine? | The maintenance manual for the APU. |
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Scanloni