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234 Cards in this Set
- Front
- Back
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What is the main advantage of a horizontally opposed engine over a radial engine for powering modern aircraft? |
The horizontally opposed engine has a much smaller frontal area and is easier to streamline than a radial engine. |
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How many throws are there in the crankshaft of a six-cylinder horizontally opposed engine? |
Six |
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How is a helicopter with a reciprocating engine cooled? |
Air is drawn through the "bell-mouth" aft intake and directed and ducted over and around the engine and down. |
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What material are most piston rings made of? |
Gray cast iron |
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What is the reason for using hydraulic valve lifters in an aircraft engine? |
Hydraulic valve lifters keep all of the clearance out of the valve operating mechanism. This decreases the wear of the valve train components. |
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At what speed does the camshaft turn, relative to the crankshaft speed in a horizontally opposed engine? |
The camshaft turns at one half of the crankshaft speed. |
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What kind of main bearings are used in a horizontally opposed engine? |
Steel-backed, lead alloy bearing inserts. |
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On what stroke is the piston of a reciprocating engine when the intake valve begins to open? |
On the exhaust stroke. |
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On what stroke is the piston of a reciprocating engine when the exhaust valve begins to open? |
On the power stroke. |
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What is meant by a cam-ground piston? |
A piston that is not perfectly round. |
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Where is the piston in a reciprocating engine when the ignition spark occurs? |
About 30 degrees of crankshaft rotation before the piston reaches top center on the compression stroke. |
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What is meant by a full floating wrist pin? |
A wrist pin that is not clamped in either the piston or the connecting rod. |
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Why do most aircraft reciprocating engines use more than one spring in each valve? |
By using more than one spring and having the wire diameter and pitch of the springs different , valve float is minimized. |
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Would excessive valve clearance cause the valves to open early or late? |
Valves will open late and close early. |
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What is the purpose of valve overlap in a reciprocating engine? |
Valve overlap allows the inertia of the exhaust gases leaving the cylinder to help the fresh induction charge start flowing into the cylinder. |
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What type of piston rings are installed on the pistons of an aircraft recip. engine? |
Compression, oil control, and oil wiper (scraper) rings |
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What caused detonation in an aircraft engine? |
Excessive heat and pressure in the engine cylinder causes the fuel air mixture to reach its critical pressure and temperature. This causes a mini explosion called detonation. |
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Why is a compression check important for determining the condition of an aircraft recip. engine? |
It can determine the seal between the piston rings and the cylinder walls, and the seal between the intake and exhaust valves and their seats. |
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What is meant by the compression ratio of a reciprocating engine? |
The ratio of the volume of the cylinder with the piston at the bottom of its stroke to the volume with the piston at the top of its stroke. |
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What are the two basic sections of a turbine engine? |
The hot and cold section. |
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What are the two basic types of compressors that are used in aircraft turbine engines? |
Axial flow and centrifugal. |
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What is the purpose of the stators in an axial-flow compressor? |
Stators convert some velocity energy into pressure energy and change the direction of the air so it is proper for the next stage of rotors. |
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What are three types of combustors used on aircraft turbine engines? |
Can, Annular, and Can-annular |
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How many igniters are there normally in an aircraft turbine engine? |
Two |
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What is the main purpose of the turbine nozzle in an aircraft turbine engine? |
The turbine nozzle directs the hot gases as they leave the combustors so the will turn the turbine wheel with maximum efficiency. |
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What is meant by a free-turbine turboshaft engine? |
A turboshaft engine that has a turbine wheel, or stages of turbine wheels, that is not used to drive the compressor of the gas generator section of the engine. |
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Why do some axial-flow turbine engines have more than one set of turbines and compressors? |
The low pressure and high pressure compressor are driven by its own turbine. The independent systems operate at which they are most efficient. |
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What kind of bearings are used to support the rotor shaft of an aircraft turbine engine? |
Ball or roller bearings. |
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What is meant by a turbofan engine? |
An axial flow turbine engine in which the first stage of compressor blades are lengthened, so they can force air around the outside of the gas generator portion of the engine. |
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Where can you find the limits of repair allowed for the compressor blades of an aircraft turbine engine? |
Service manual. |
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Why is it important that a turbojet engine be allowed to cool before it is shut down after it has been operated at a high power setting? |
If the engine is shut down while it is hot, there is a possibility that the shroud will contract around the turbine wheel and seize the rotor. |
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What is meant by a hung start in a turbine engine? |
When the engine fails to reach idle |
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What is meant by a hot start in a turbine engine? |
When EGT is to high at start causing damage to the engine. |
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What is meant by creep of the turbine blades? |
Permanent elongation of the turbine blades. |
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Where is water injected into a turbine engine for cooling purposes? |
Into the compressor inlet and into the engine diffuser case. |
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At what point in a turbine engine is the temperature the highest? |
Turbine inlet. |
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What is the function of interconnect tubes between the cans of a turbine engine that uses can-type combustors? |
The tubes allow the flame to travel from the cans that contain the igniters to all of the other cans. |
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What are the two types of thrust reversers that are used on a turbojet engine? |
Mechanical blockage type and Aerodynamic blockage type |
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What is meant by trimming a turbojet engine? |
Adjusting the fuel control to get the correct idling and maximum-thrust RPM |
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What determines whether or not a 100-hour inspection is required for an aircraft? |
100-hr inspections are required only on aircraft that carry people for hire or to give flight instructions. |
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Where can you find a list of items that should be inspected on a 100-hr and annual inspection of an aircraft engine? |
FAR 43 Appendix D |
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In what publication can a mechanic find the operating limitations for an aircraft engine? |
TCDS |
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Who is authorized to perform the powerplant inspection that is required for an annual inspection? |
An IA |
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What are the two types of compression checks that can be performed on an aircraft reciprocating engine? |
A Differential and a Direct compression check. |
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What items are checked in a hot section inspection of a turbine engine? |
The turbine wheel, the turbine case, and the exhaust section are checked for cracks, indications of overheating, and any indication of war-page, erosion, or burning. |
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What is the most common type of damage that is found in the hot section of a turbine engine? |
Cracks |
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Is the use of a checklist required when performing an annual or 100-hr inspection of an aircraft engine? |
Yes |
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What inspection must be performed on an aircraft reciprocating engine if it has been operated on turbine fuel? |
The cylinders must be inspected with a borescope. The oil must be changed and filters examined, and given a run-up check. |
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In what units is the tachometer for a recip. engine calibrated? |
In hundreds of RPM. |
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In what units is the tachometer for a turbine engine calibrated? |
In percent of the engines rated takeoff power. |
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Where does the manifold pressure gauge used on an aircraft recip. engine pick up the pressure it measures? |
From the intake manifold of the engine. |
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What is used to measure the fuel flow of a horizontally opposed, fuel injected recip. engine? |
A pressure gauge that measures the pressure drop across injector nozzles. |
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What is indicated if the needle of a ratiometer-type oil temperature indicator pegs to the high side of the dial as soon as the aircraft master switch is turned on? |
There is an open in the bulb circuit that causes the instrument to see an infinite resistance. |
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What type of indicating system is used to measure the exhaust gas temperature of a turbine engine? |
A set of thermocouples arranged in an averaging circuit. |
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What should a thermocouple-type cylinder head temperature indicator read when the engine is not operating? |
The temperature of the outside air. |
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What two pressures are measured to get the engine pressure ratio of a turbojet engine? |
The turbine discharge total pressure and the compressor inlet total pressure |
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What kind of mechanism is normally used to measure oil pressure in a recip. engine? |
A bourdon tube mechanism |
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What is measured by the tachometers used on a two spool gas turbine engine? |
The N1 tachometer shows the RPM of the low-pressure compressor and the N2 tachometer shows the RPM of the high pressure compressor. |
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Does the tachometer of a geared recip. engine indicate the speed of the crank shaft or of the propeller shaft? |
The speed of the crankshaft. |
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Can a thermal switch type fire detection system indicate a general overheat condition? |
No |
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Can a thermocouple-type fire detection system indicate a general overheat condition? |
No |
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Does a break in a continuous-loop fire detection system keep the system from detecting a fire? |
No |
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Does the pressure-type continuous-element fire detector system detect a general overheat condition, as well as fire? |
Yes |
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What are the two most commonly used fire extinguishing agents used for engine fires? |
Halogenated hydrocarbon (Halon 1301) and carbon dioxide |
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What extinguishing agent is used in the high-rate-discharge fire extinguishing systems installed in most turbojet engine installations? |
Halon 1301 |
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How can a mechanic determine a state of charge of the HRD bottles of fire extinguishing agent? |
A pressure gauge on the bottle shows the pressure of the contents of the bottle. |
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What method is used to discharge an HRD bottle in a turbine engine installation? |
An electrically ignited powder charge blows a knife through the seal on the bottle and discharges the contents. |
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Which type of fire detection system operates on the rate of temperature rise? |
The thermocouple system. |
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What is indicated if the yellow blow-out plug of the fire extinguishing system on the side of an engine nacelle is blown out? |
The built in fire extinguishing system has been discharged normally. |
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What is indicated if the red blow-out plug of the fire extinguishing system on the side of an engine nacelle is blown out? |
The built in fire extinguishing system has been discharged by a high temperature condition. |
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How is a pressure-type continuous-element fire detector system checked for operation? |
Low voltage alternating current is sent through the sheath of the detector element. This heats the element, and it releases enough gas to close the diaphragm switch. |
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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. |
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What two things must be considered when selecting the size wire to use when making an electrical installation in an aircraft? |
The current carrying capability of the wire and the amount of voltage drop that is caused by current flowing through the wire. |
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Why are the wires in certain electrical installations twisted together? |
By twisting the wires together, the magnetic fields caused by current flowing in the wires are minimized. |
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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. |
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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 are enclosed in some type of protective conduit. |
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What is the minimum separation that is allowed between a wire bundle and a fluid line that carries combustible fluid or oxygen? |
6 inches. |
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What is the significance of the color of the solderless connectors that are used on electrical wires? |
The color of the insulation indicates the size of the wire the connector will fit. |
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What is the maximum number of wire terminals that may be stacked on a single stud in a terminal strip? |
4 |
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What is the purpose of shielding that is used to encase some electrical wires? |
Shielding intercepts radiated electromagnetic energy and carries it to ground so it will not interfere with any nearby sensitive electronic equipment. |
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What is used as the rectifier to produce direct current in a DC generator? |
Brushes and a commutator. |
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What is meant by paralleling the generators of a twin-engine aircraft? |
Adjusting the voltage of the generators so they will share the electrical load equally. |
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What is meant by flashing the field of a DC generator? |
Restoring the residual magnetism to the frame of a generator. |
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What kind of rectifier is used in a DC alternator of the type that is used on most of the modern light airplanes? |
A full wave, three phase rectifier made up of six silicon diodes. |
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What is used to maintain a constant frequency of the alternating current that is produced by an AC alternator driven by an aircraft turbine engine? |
A hydraulic constant-speed drive unit between the engine and the alternator. |
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What three things must be synchronized before a three-phase AC generator can be connected to a bus that is being served by another generator? |
The voltage the, the frequency, and the phase rotation of the generators. |
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What must be done to reverse the direction of rotation of the armature of a DC electric motor? |
The current flow must be reversed through the armature or the field windings. (but not through both) |
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Does a series-wound DC motor have a high or a low starting torque? |
High starting torque. |
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Which aircraft electrical circuit does not normally contain a fuse or a circuit breaker? |
The starter motor circuit. |
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When removing a battery from an aircraft, which connection should be removed first? |
The ground (the negative) is removed first and connected last. |
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What is meant by the effective voltage of sine wave alternating current? |
The value of the alternating current that is needed to produce the same amount of heat as this value of direct current. |
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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. |
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What is meant by the viscosity of engine lubricating oil? |
The resistance of the oil to flow. |
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What is meant by a wet sump lubrication system? |
A lubrication system in which the oil is carried inside the engine itself. |
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What is meant by a dry sump lubrication system? |
A lubrication system in which the oil is carried in a tank that is not a part of the engine. |
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How is oil temperature controlled in an aircraft recip. engine? |
Hot oil is directed through the core of the oil cooler, cold oil is directed around the cooler so it will not be cooled further. |
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Is the oil temperature shown on the aircraft instrument panel the temperature of the oil entering the engine or of the oil leaving the engine? |
Oil entering the engine. |
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What is the function of the hopper in the oil tanks used with some recip. engines? |
Oil in the hopper is diluted. This speeds up the dilution and requires less gasoline. |
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What happens to the gasoline that is used to dilute the oil in the crankcase of an aircraft recip. engine? |
When the engine is running and the oil is warm, the gasoline evaporates out of it. |
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What is the purpose of the sludge plugs in the crankshaft of a recip. engine? |
They trap sludge that is in the oil and hold it until the engine is disassembled at overhaul. |
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Which pump is the larger in a dry-sump lubricating system, the pressure pump or the scavenger pump? |
The scavenger pump has the greater volume. |
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Why do full flow oil filters have a spring-operated bypass in them? |
If the filter becomes blocked the bypass will allow unfiltered oil to flow to the system. |
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What is the function of a fuel-oil heat exchanger in the lubrication system of a turbojet engine? |
This allows heat from the oil to warm the fuel so ice will not form on the fuel filters. |
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What kind of oil is used in most turbojet engines? |
Synthetic oil. |
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Where are the last chance oil filters located in a turbojet engine? |
They are located inside the engine just ahead of the nozzles that spray oil onto the bearings. |
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Where is the oil tank in a dry-sump recip. engine vented? |
To the engine crankcase. |
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What information must be displayed around the oil filler opening for a turbojet engine? |
The word "oil" and permissible oil designations.(Grade of oil) |
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What is the function of the oil control rings on the piston of an aircraft recip. engine? |
They maintain the proper quantity of oil between the piston and the cylinder wall. |
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What indication would a pilot have if his oil supply was low? |
The oil temperature would be high and the oil pressure would be low. |
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What is meant by a hot-tank lubrication system? |
A lubrication system in which the oil cooler is located in the pressure subsystem. |
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What is meant by a cold-tank lubrication system? |
A lubrication system in which the oil cooler is located in the scavenge subsystem. |
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What is the main advantage of a magneto ignition system over a battery ignition system for an aircraft recip. engine? |
A magneto has its own source of electrical energy, and it is not dependent on a battery. |
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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. |
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What is the significance of the numbers on the distributor of an aircraft magneto? |
These numbers are the sparking order of the magneto. |
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What is done in a magneto ignition system when the ignition switch is placed in the OFF position? |
The primary circuit is connected to ground. |
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What is the reason for having a low-tension ignition system on some aircraft? |
Low tension magnetos are used on aircraft that fly at high altitudes where there is a problem with flashover in the high tension magneto distributor. |
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What is the basic difference between a low-tension and a high-tension magneto? |
The low tension ignition system has only one coil in the magneto and uses a carbon brush type distributor. A high tension magneto produces high voltage in the magneto coil and is sent to the correct spark plug by the built in high voltage distributor. |
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What is meant by 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. |
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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. |
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What is the difference between a hot spark plug and a cold spark plug? |
A hot spark plug has a longer path for heat to travel to a cold spark plug has a shorter path. |
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What is checked when a magneto is internally timed? |
Adjust breaker points so they will open at the instant the magnet is in E-gap and distributor rotor is in the position to direct the high voltage to cylinder number one. |
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What is the purpose of a vernier coupling used on some aircraft magneto drives? |
It allows the magneto to engine timing to be varied in increments of less than one degree. |
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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. |
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Why is it important that the spark plugs be kept in numbered holes in a tray when they are removed? |
To tell the internal condition of the cylinders from which they were taken from. |
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What is the purpose of staggered timing between the two magnetos on an aircraft engine? |
By using staggered timing the flame front caused by the two spark plugs will meet in the center of the piston. |
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In what position should the ignition switch be placed when using a timing light on the magnetos? |
Both position |
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Why is it important that a torque wrench always be used when installing spark plugs in an aircraft engine? |
If they are not tight enough there will be a poor seal but if they are too tight there is a danger of cracking the insulation. |
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Why are pressurized magnetos used on most recip. engine powered aircraft that fly at high altitudes? |
By pressurizing the distributors the high voltage is kept from arcing across to the wrong electrode and causing vibration and loss of engine power. |
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What type of ignition system is used on most turbine engines? |
High intensity, intermittent duty, capacitor discharge ignition systems. |
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What is meant by the E-gap in magneto timing? |
E-gap is the position of the rotating magnet when the primary current flowing in the magneto coil is the greatest. |
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What kind of gauge should be used to measure the electrode gap in aircraft spark plugs? |
A round wire gauge. |
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How many igniters are used in most turbine engines? |
Two |
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What are two types of ignition systems used in turbine engines? |
High voltage and low voltage systems. |
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With which type of ignition system is a glow plug igniter used? |
A low voltage system |
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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. |
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In what position is the magnet in a magneto when the greatest change in flux density in the coil core takes place? |
A few degrees beyond neutral. |
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In what position is the magnet in a magneto when the breaker points begin to open? |
It is in E-gap position. |
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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? |
The ignition switch is not grounding the magneto primary circuit. |
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What turns on the auto ignition system in a turboprop engine? |
A torque pressure switch energizes the system when the engine stops producing torque. |
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Where does the fuel metering system of a turbine engine discharge its fuel? |
It is discharged through spray nozzles into the combustion chambers. |
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What is adjusted when the fuel control unit of a turbine engine is trimmed? |
The idle speed and the maximum thrust speed. |
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What are two locations water may be injected into a turbine engine? |
At the compressor inlet and at the inlet to the diffuser section. |
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What is meant by a duplex nozzle in a turbine engine fuel metering system? |
A duplex fuel nozzle is one that has two fuel discharge passages. |
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Does the fuel air mixture provided by a float carburetor become richer or leaner as the aircraft goes up in altitude? |
If the mixture is not adjusted it will become richer as it gains altitude. |
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Does the fuel air mixture provided by a float carburetor become richer or leaner when carburetor heat is applied? |
Richer |
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What would happen to the fuel air mixture ratio in a float carburetor if the main air bleed were to become plugged? |
The mixture would become excessively rich. |
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How does the automatic mixture control in a pressure carburetor keep the fuel air mixture constant as the aircraft changes altitude? |
It automatically bleeds the air between the two sides of the diaphragm and decreases the air metering force. |
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What are the two purposes of the manifold valve (flow divider) in the fuel injection system of a horizontally opposed aircraft engine? |
It provides a constant discharge fuel pressure for idling and provides a positive shutoff for the fuel when the engine is shut down. |
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How does the mixture control change the fuel air mixture ratio on the Teledyne-Continental fuel injection system? |
When mixture control is in FULL Rich all fuel goes to the manifold valve. When it is in the Idle Cutoff all fuel is returned to the pump inlet. |
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Why must the diaphragms of a pressure carburetor be soaked before the carburetor is ready for flight? |
It restores them to the condition of flexibility that they had when the carburetor was calibrated. |
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What are two basic types of fuel controls for aircraft turbine engines? |
Hydro-Pneumatic and Electro-Hydromechanical |
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What two things are adjusted when adjusting the idling of a recip. engine? |
The throttle stop and the idle mixture control. |
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What is controlled by the adjustment of the orifice in the fuel pump of a Teledyne-Continental fuel injection system? |
The high unmetered fuel pressure. |
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What is the significance of the letters that are stamped on the flats of a fuel injection nozzle? |
The letters designate the relative size of the orifice in the injector nozzle. |
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What is the function of the derichment valve in a pressure carburetor used on an aircraft engine with an anti detonation injection system? |
The valve automatically closes to lean the fuel air mixture when ADI fluid is flowing. |
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What is the function of the economizer system in an aircraft engine carburetor? |
The system allows the engine to operate with an economically lean mixture for all conditions other than full power. |
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In what position is the mixture control placed for starting an engine that is equipped with a pressure carburetor? |
In the idle cutoff position. |
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In what position is the carburetor heat control placed when starting an aircraft engine? |
Cold position. |
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Why is an aircraft recip. engine killed by placing the mixture control in the cutoff position, rather than by using the magneto switch? |
With no fuel in the cylinders the engine is less likely to fire if the propeller is pulled through with ignition switch accidentally on. |
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Where is the fuel from a continuous-flow fuel injection system discharged? |
Through the injector nozzles screwed into the cylinder heads near the intake valves. |
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What engine parameters are sensed by the fuel control unit of a turbine engine? |
Engine RPM, inlet air pressure, compressor discharge pressure, burner can pressure, and inlet air temperature. |
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When does the acceleration system operate on an aircraft carburetor? |
When the throttle is suddenly opened. |
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What is the purpose of the bypass valve in an engine driven fuel pump? |
The bypass valve allows fuel to flow around the engine driven pump for starting and for emergency operation if the engine driven pump should fail. |
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On which side of the firewall is the engine fuel shutoff valve located? |
The side away from the engine. |
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What are the three purposes for the boost pumps in an aircraft fuel system? |
To provide fuel pressure for starting, to pressurize the fuel lines to prevent vapor lock, and to transfer fuel from one tank to another. |
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What kind of boost pump is used in most aircraft fuel systems? |
Electrically operated centrifugal pumps. |
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Where does an engine driven fuel pump direct the excess fuel from its pressure relief valve? |
Back to the inlet side of the pump. |
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What causes a vapor lock in an aircraft fuel system? |
When the fuel boils and the vapors block the fuels lines so the liquid fuel cannot flow to the engine. |
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What is done in most aircraft fuel systems to prevent vapor lock? |
Boost pumps in the fuel tank pressurize the fuel in the lines and force the fuel into the fuel metering system. |
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What is meant by a compensated relief valve in an engine driven fuel pump? |
A pressure relief valve that is acted upon by a diaphragm as well as a spring. |
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What is the purpose of the pressurizing and dump valve in the fuel system for a turbine engine? |
The P&D valve acts as a flow divider directing the fuel into the main or pilot manifold so it will be discharged from the proper orifice. |
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What should be done to an aircraft reciprocating engine if it has been operated on turbine engine fuel? |
All of the fuel should be drained out, engine given compression check, cylinders inspected with a borescope, oil changed and filter examined. |
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What are two basic types of turbine engine fuel? |
Jet A and Jet A-1 |
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Why do some turbine engine fuel systems incorporate a fuel heater? |
The fuel heater keeps the fuel warm enough that any water in the fuel wont freeze. |
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What are two reasons prist is used in turbine engine fuel? |
It lowers the freezing point of any water and kills microbial growth |
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Why do some aircraft fuel filters have a built in relief valve? |
The valve will open and allow unfiltered fuel to flow should the filter become clogged. |
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What is a roots blower? |
An engine driven supercharger. |
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Where is the heat taken from that is used to heat the induction air in a recip. engine? |
From a muff that is installed around the exhaust system. |
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Where does the alternate air come from that is used with a pressure carburetor or a fuel injection system? |
From inside the engine cowling. |
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Where does carburetor ice normally form in a carburetor? |
In the throat of the carburetor and around the throttle valve. |
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Does the application of carburetor heat cause the fuel air mixture to become richer or leaner? |
Richer. |
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What is used to drive most of the external superchargers used on modern recip. engines? |
Exhaust gases. |
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What controls the speed of a turbocharger compressor? |
The amount of exhaust gas that is forced to flow through the turbine. |
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What is meant by a convergent inlet duct for a turbine engine? |
Becomes smaller in the direction of airflow. |
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What is meant by a divergent inlet duct for a turbine engine? |
Becomes bigger in the direction of airflow. |
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What kind of inlet duct is often used on turbine powered helicopters? |
A bell mouthed inlet duct. |
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What is the danger of operating an aircraft recip. engine with too high a carburetor air temperature? |
It can cause the fuel air mixture to reach its critical temperature and detonate. |
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Why do some turbine engines use variable inlet guide vanes? |
They are automatically adjusted to direct air into the engine in such a way that it keeps RPM vs. Velocity proper for the most efficient operation. |
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How do some turbine engines prevent ice formation on the inlet guide vanes? |
Hot compressor bleed air flow through. |
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What is usually installed in a large recip. engine between the turbosupercharger and the carburetor? |
An intercooler. |
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In what position should the carburetor heat control be placed when starting a recip. engine? |
Cold position. |
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How does an engine air inlet vortex destroyer help prevent foreign object damage to the engine? |
A high velocity stream of compressor bleed air is blown out in front of the engine to break up vortices that form in front of the engine when it is operating. |
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What is meant by pressure cooling of an aircraft engine? |
Air cooling in which air is forced to flow through baffles and cylinder fins by a pressure differential across the engine. |
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What is the purpose of an augmentor tube in the cooling system of an aircraft recip. engine? |
The tube augmentor tube uses the velocity of the exhaust gases to produce a low pressure on one side of the engine that helps pull cooling air through it. |
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Where is the highest temperature located in a turbine engine? |
The inlet to the high pressure turbine. |
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How are the turbine inlet guide vanes and the first stage turbine blades in some turbine engines cooled? |
High pressure compressor bleed air flows through the guide vanes and turbine blades. |
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Which side of an air cooled engine has the greatest amount of cooling fins? |
The exhaust side. |
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What should be done to repair a bent cooling fin in a cast aluminum cylinder head? |
Leave it alone if it does not restrict the airflow. |
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What is used in a helicopter to increase the amount of cooling air that flows over the engine cylinders? |
A belt driven fan. |
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What should be the position of the cowl flaps on a recip. engine when it is run on the ground? |
Open. |
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What is the function of the majority of the air that passes through a turbine engine? |
Most is used for cooling. |
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How is the structure around a turbine engine protected from excessive heat from the engine? |
An insulating blanket protects the structure from excessive heat. |
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What is the function of blast tubes that are installed in a pressure cooling system of a recip. engine? |
They direct cooling air to the magnetos and the generator. |
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What material is the insulation blanket made of that is used to protect the aircraft structure from the heat produced by a turbine engine? |
Fiberglass sandwiched between the sheets of metal foil. |
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What material are most recip. engine exhaust components made of? |
Corrosion resistant steel. |
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How is the speed of a turbocharger controlled? |
The waste gate controls the amount of gas that flows through. |
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What type of actuator is used to control the position of the turbocharger waste gate? |
A hydraulic actuator that uses engine oil pressure to move the piston. |
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How does a power recovery turbine increase the power of a recip. engine? |
Exhaust driven velocity turbines are coupled through a hydraulic drive to the engine crankshaft. |
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How tight should the clamps be tightened that hold sections of a recip. engine exhaust system together? |
They should not be so tight that they will be damaged when heat expands the exhaust system components. |
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What would be the effect on engine performance of an internal failure of a muffler? |
This will increase the exhaust back pressure and cause a loss of engine power. |
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What effect on turbine engine operation is caused by a change in the area of the exhaust nozzle? |
Altering the area of the exhaust nozzle affects the compression ratio, the RPM, mass airflow through the engine, and EGT. |
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What are two types of thrust reversers that are used with turbojet engines? |
Mechanical blockage (clam shell) and aerodynamic blockage (cascade). |
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How does a noise suppressor reduce the amount of noise produced by a turbojet engine? |
It breaks up the low frequency vibrations in the exhaust stream and converts them into higher frequencies. |
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What is the purpose of the ball joints and bellows in the exhaust system of a recip. engine? |
They allow the exhaust system components to change their dimensions without causing any leaks. |
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Why do some supersonic aircraft use a convergent-divergent exhaust duct? |
A CD exhaust duct controls the gas expansion as it leaves the engine so the gases will produce thrust at supersonic velocities. |
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Why is it important that a lead pencil never be used to mark on an aircraft exhaust system? |
It will cause the metal to become brittle and likely to crack. |
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What type of damage is normally found in the hot section of a turbine engine? |
Cracks. |
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What type of device is used on propeller blades to remove ice that has formed on them? |
Electrically heated deicer boots. |
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What is used to prevent ice forming on a propeller blade? |
A mixture of ethylene glycol and isopropyl alcohol slung out along the blades. |
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Should an adjustable pitch propeller be in high pitch or low pitch for takeoff? |
Low pitch. |
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What is done to a hydromatic propeller to feather? |
High pressure engine oil is directed into the propeller through the governor. |
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What is done to cause a McCauley propeller to feather? |
Oil is allowed to drain out of the propeller. |
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Does centrifugal twisting moment on a propeller blade tend to move the blades toward high pitch or low pitch? |
Toward low pitch. |
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Do the counterweights on a propeller tend to move the blades toward high pitch or toward low pitch? |
Toward high pitch. |
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What is the difference between a controllable propeller and a constant speed propeller? |
A controllable pitch propeller uses a manually operated oil valve to control pitch and a constant speed propeller uses a governor to control the valve. |
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When making a magneto check on an engine equipped with a constant speed propeller, should the propeller be in the low pitch or the high pitch position? |
It should be in the low pitch position. |
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What can be done to prevent the front cone bottoming when installing a propeller on a splined shaft? |
Install a spacer behind the rear cone to move the propeller forward on the shaft. |
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What is the purpose of the small holes that are drilled in the end of a wooden propeller? |
These holes vent the inside of the propeller blade and allow moisture that collects in the wood to be released. |
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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. |
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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. |
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What is the function of the accumulator that is used with some McCauley feathering propellers? |
It stores oil under pressure when the engine is operating normally. |
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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. |
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Is the flat surface of a propeller blade the face of the blade or the back of the blade? |
The face of the blade. |
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What keeps a McCauley feathering propeller from feathering when the engine is shutdown on the ground? |
A spring loaded latch mechanism prevents the blades from moving into the feather position when the engine is shut down on the ground. |
