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A&P Powerplant Oral Questions, ASA-OEG-AMT2 |
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In what position should the crankshaft be when a magneto is being timed to the engine? - ✔✔The piston and cylinder number one 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 is not as hot as the others is the cylinder that has not been firing What is checked on engine run out to determine the operational condition of the engine? - ✔✔Idling rpm and manifold pressure, engine acceleration, maximum static RPM and manifold 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, 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 cylinders that 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, cylinder, or connecting rod will be damaged. How is 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 is directed through a very short high tension lead to the spark plug. There is one transformer for each spark plug.
What is a floating cam ring in a large radial engine? - ✔✔It is a cam ring that rides on a shelf type bearing with a large amount of clearance between the bearing in 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 must be removed so the cam ring will be tight against the bearing for the valves to be adjusted. 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 check 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 and troubleshooting an engine installation? - ✔✔A. Know how the system should operate. B. Observe 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.
- check for unusual noise when the compressor is rotated.
- inspection of the rear turbine, and exhaust system.
- check the quantity of the lubricating oil for the engine and the constant speed drive unit.
- check the ignition system for operation by listening for the sparks. 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 standard 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? - ✔✔Vein 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 damage 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? - ✔✔Between 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 gauge by a copper tube. The pressure of the gas above the liquid is proportional to the temperature of the oil that surrounds the bulb, and the pressure gauge is calibrated in terms of temperature. 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 airplane's? - ✔✔A magnetic drag tachometer that is similar to an automobile speedometer.
How does a ratiometer-type oil temperature gauge measure the temperature of the oil? - ✔✔A ratiometer measures the resistance of the temperature bulb. The indicator is calibrated in degrees Fahrenheit or Celsius rather than in ohms. What is the range of pressure needed for a fuel pressure gauge used with a float carburetor? - ✔✔Normally from 1 to 25 PSI. What are four types of engine fire detection systems? - ✔✔Thermal switch 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 it's 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 an engine is pulled? - ✔✔The engine fuel shut off 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 shut off valve is closed. The hydraulic pump low pressure warning lights are turned off. What is used as a fire extinguishing agent in some older aircraft? - ✔✔Carbon dioxide (CO2). 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 disc 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 electrical 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 and 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 identify 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 of 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 the minimum separation allowed between a wire bundle and a fluid line that carries combustible fluid or oxygen? - ✔✔6 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 turbine engine. When the engine is running, the circuitry automatically shifts so it acts as a compound-wound generator. When should Aircraft wiring be installed in a conduit? - ✔✔When the wiring passes through an area in the aircraft where open wiring would 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 anytime an excessive amount of current flows, regardless of the position of the circuit breaker's operating handle. Which way should the toggle switch 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 through-out the oil so they will not clump and clog oil passages. They 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 needed 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 of the engine. E. Protects against corrosion. F. Performs hydraulic action Where can you find the grade of engine oil specified for a particular aircraft? - ✔✔In the aircraft flight manual or the pilots 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 strainer screen, the oil filter, the oil cooler and the temperature control valve, the oil pressure and temperature gauges and any transmitters associated with them, and the entire engine for indication of oil leaks. What two instruments show the condition of a reciprocating engine lubrication system? - ✔✔Oil pressure and oil temperature gauges. What must be done to and oil filter when it is removed from the engine? - ✔✔It should be cut open and the pleated element examined to determine the type and amount of contaminant carried by the oil. What is spectrometric oil analysis program? - ✔✔A program in which a sample of oil is taken from the engine at regular intervals and sent to a laboratory, where it is burned in an electric arc. The resulting light is analyzed for the wavelengths of the elements that are present in the oil sample. Traces of aluminum, copper, and iron in the oil indicate wear of the pistons or wrist pin plugs (aluminum), cylinder walls or piston rings (iron), main bearings or bushings (copper). A single sample is meaningless. There must be a series of samples taken at regular intervals to measure the change in the amounts of these metals.
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 I magneto is internally time? - ✔✔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 it's E-gap position. What is the function of an impulse coupling? - ✔✔An impulse coupling is a spring driven coupling between the magneto in 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 releases the magnet and the spring spins it fast so that it produces a hot and late spark. How many igniters are used in most turbine engines? - ✔✔Two What are two types of ignition systems used in turbine engines? - ✔✔High-voltage systems and low- voltage systems. 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 magnetos 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 it's 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 spark plug, 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 firing end that is more open than that of a massive electrode spark plug. The open firing end allows the gases that contain lead to be purged from the spark plug so they will not form solid lead contaminants. 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 detonation or overheating.
What prevents too high an air pressure from over speeding an air turbine starter? - ✔✔The air shut off and regulating valve. Where does an air turbine starter get its 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 particles in 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 measure the fuel to The nozzles in such a way that prevents over shooting of power changes and over temperature conditions. FADEC furnishes information to the engine indication and crew alerting system (EICAS). 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? - ✔✔Anytime 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 date it was obtained when the engine was calibrated in the manufacturers test cell. Where should ambient temperature be measured when trimming a turbine engine? - ✔✔In a shaded area is 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 What is the function of a float carburetor? - ✔✔A float carburetors function is to measure air flow through the engine induction system and dispense the appropriate amount of gasoline into the airflow for all engine operating parameters and conditions. It must also provide the fuel in a state that is as vaporized as possible by the time ignition occurs in the engine cylinders. 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 engines? - ✔✔Teledyne Continental (TCM) system and Percision 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 outlet 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 Percision Airmotive system to control the amount of fuel sent to the nozzles? - ✔✔The mass of 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.
How is ice prevented from forming on the nose cowl, nose dome and inlet guide veins 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 would occur. Why is it very important that the induction air filters be Clean and replaced as often as the manufacturer recommends? - ✔✔Clogged air filter's 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? - ✔✔All of 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 fans 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 pilots operating handbook (POH). 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 wastegate open or closed? - ✔✔Open, so as much exhaust as possible will bypass the turbine. Why are thrust reverser's not normally used when the airplane is moving below approximately 60 knots?
- ✔✔There is a danger of recirculating the exhaust gases, and of the engine ingesting foreign object stirred up by the high velocity gases. 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 door shut off the flow of gases from the core engine and deflect it through cascades that direct it forward. What is meant by a slave engine with regard to propeller synchronization? - ✔✔This is the engine in a multi-engine 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 a 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 pitch changes the air load on the propeller which changes the RPM. 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 surface
