Study Flashcards
What type of piston rods are commonly found in radial engines
A master and articulating rod assembly
What is detonation
Ignite spontaneously and burn with explosive violence
Where is a crack most likely to occur on a piston
Piston pin/wrist pin
What types of damage may be found when inspecting compressor blades
Dents, scratches, gouges, galling, burns, burrs, pitting, and cracks
How are compressor blades attached to a disk type rotor
Fit into the disks by either bulb type, fir-tree, or dovetail type roots. Locked by means of screws, peening, locking wire, pins, or keys
What is the purpose of the nozzle diaphragm, or turbine nozzle
Guides combustion gases to the turbine section for maximum turbine rotation
What is the effect of air density on the thrust of a turbine engine
Determines the mass of air that is used by a jet engine
What are the two most common types of thrust reverse
Mechanical blockage type and aerodynamic blockage type
What is a split compressor system in a turbine engine
Requires two concentric shaft joining the turbine stages to their respective compressors
What is a free turbine
Rather than driving the compressor rotor, drives a propeller or helicopter transmission
What are the units in an engine fuel flow system
Transmitter and an indicator
Where is the fuel flow transmitter located
Between the engine driven pump and the carburetor
What exactly does a mass fuel flow transmitter measure
Density mass of the fuel that flows through it
What is the reason for monitoring the fuel flow
Wheather the engine is operating at the correct fuel air mixture for a given power setting
What does manifold pressure gauge indicate
Measures absolute pressure in the intake manifold
What would be the effect of a broken manifold pressure gauge line
Indicates atmospheric pressure
What does the engine tachometer indicate
Crankshaft speed (RPM)
What is the most likely cause of an oscillating tachometer
Kink in the cable
What type of tachometer is used in multi engine airplanes
Alternating current tachometer generators
What are turbine engine tachometers designed to indicate
Percent of engine rotor (shaft) RPM
What is the EPR on a turbine engine
Ratio between total turbine discharge pressure to total inlet pressure. Indicates the thrust being developed by the engine
Where is a carburetor air temperature bulb located
Air intake passage to the engine
How can a turbine engine EGT be checked without operating the engine
Checking resistance to thermocouples and circuits.
What is the typical acceptable resistance of a cylinder head thermocouple cable
2 to 8 ohms
What are the main categories of engine fire protection systems
Spot detection, continuous loop, and flame detectors
How many thermocouples are required for engine fire detection
Depends on the size of the fire zone and total circuit resistance
Describe the operation of a kidde continuous loop fire detector system
Ceramic core material heats up its resistance drops completing a circuit between the internal wires lighting a light
What is the most common cause of false fire warning in a continuous loop detector system
Dance, kinks, or crushed sensing elements.
What two methods are used to discharge fire extinguishing agents
Mechanical and electrical
What method is used to release the fire extinguishing agent in a typical turbine engine fire protection system
Squibs
What is the color marking used to identify fire extinguishing lines
Brown tag with a row of black diamonds
What are two methods commonly used to distribute the fire extinguishing agent to the engine
Perforated tube or discharge nozzles
How does the fire extinguishing agent put out the fire
Dilutes the atmosphere so that it will not support combustion
How is the fire extinguishing agent distributed from a HRD system
Open end tubes
Which type of fire detection system gives a more complete coverage to a fire hazard
A continuous loop system
How would you seat newly installed generator brushes to the commutator
Use fine green sandpaper placed around the commutator with the sanding surface facing out word
What units make up a DC generator three unit regulator
Voltage regulator, current limiter, and reverse current cutout
What method is used to control the voltage of an aircraft alternator
Voltage regulator
What determines the frequency of the voltage of an alternator
Speed of rotation of the rotor and the number of poles
What are the three basic types of DC motors
Series motor, shunt motors, and compound motors
Name the parts of a DC motor
The Armature, brushes, commutator, and field frame
Why should strand wire be used in powerplant applications
Less likely to fatigue and break from vibrations
What is open wiring
Wire not enclosed in conduit
What methods are used to control the voltage output of DC aircraft generator
The vibrating type voltage regulator, three unit regulator, and carbon pile
What are the causes of excessive arcing at the generator brushes
Commutator that is dirty, rough, or out of round. Worn or binding brushes, or when brush spring tension is too low
What precautions should be taken when running wires close to heating ducts or exhaust stacks
Wire should be insulated with a high temperature resistant material
What are the purposes of reciprocating engine oil
Cleans, cools, cushions, seals, and lubricates parts
What factors must be considered in determining the proper grade of oil to use in a specific engine
Operating load, rotational speed, and operating temperatures
What are the main oil contaminants
Gasoline, moisture, acid, dirt, carbon, and metallic particles
What could cause oil foaming
Diluted oil, contaminated oil, or the oil level is too high
What would be an indication of an inadequate oil supply
Low oil pressure and high oil temp
Where can you find the specified grade of oil for a particular aircraft
AFM, or the pilots operating handbook
What are two types of oil coolers used in turbine engine lubrication systems
Air cooled and fuel cooled
What is the meaning of oil flashpoint? Fire point?
Temperature at which the oil will begin to give of ignitable vapors. Fire point is the temperature at which there are sufficient vapors to support a continuous flame
What is the weight of aircraft engine oil
7.5 pounds per US gallon
What is the primary purpose of engine oil lubricant
Reduce friction
What is the S.O.A.P. Analysis
Oil analysis system that establishes a trend to measure engine health
Where carbon seals used in turbine engines
Aircraft gearboxes, air turbine motor starters, and main shaft seals
What is the key purpose of lubrication in a turbine engine
Lubrication of the main shaft bearings
Where are engine oil filters located
Between the oil pump output and the engine bearings
Why do reciprocating engines require oil with a high viscosity index
Easier starting in cold temperatures and prevents the oil from becoming too thin and operating temperatures
Why do reciprocating engines require high viscosity oil
They have large clearances, high operating temperatures, and high bearing pressures
What is a magneto
Self-contained AC generator driven by the engine for the purpose of ignition
What is the purpose of the condenser in a high tension magneto electrical system
Prevent arcing at the points and to hasten the collapse of the magnetic field
What is the E gap position
The poles of the rotating magnet are a few degrees past the neutral position
What are the three major circuits of a high tension magnetos system
Magnetic circuit, primary electrical circuit, and secondary electrical circuit
What are the components of a high tension magnetic circuit
Permanent rotating magnet, soft iron core, and pole shoes
What happens when the primary breaker points open in a magneto
Stops the flow of current in the primary coil
What three conditions are required to fire plugs in a cylinder when the piston is in the prescribed position
E gap position, the breaker points must open and the distributor rotor must be aligned with a distributor electrode for that cylinder
What is internal timing of a magneto
Adjusting the breaker points to open when the polls of the rotating magnet are at the E gap position
What is the purpose of an impulse coupling used with a magneto
Used to retard the timing of the spark to after top dead center for starting the engine
What is the proper spark plug reach
When the electrode end of the plug inside the cylinder is in the best position to achieve ignition
What type of ignition system is used in most turbine engines
Electronic capacitor type ignition system
What is the function of the igniter plugs in a turbine engine
Provide a discharge gap for the current which is stored in the capacitor
What are two types of igniter plugs
Annular rum and constrained gap
What is an advantage of air turbine starters, when compared to electric starters, for large turbine engines
Lightweight, do not have the same cooldown periods as electric starters
Why do turbine igniters not get carbon found as often as reciprocating engine spark plugs
Due to extreme high rates of electrical discharge
What are three parts of an ignition system of a turbine
Igniter, exciter, ignition lead
Where are the fuel spray nozzles located in a turbine engine
Externally or internally on the combustion chamber in such a way that the fuel can be sprayed into the combustion area
Name the heat sources for the operation of fuel heaters used in turbine engines
Bleed air or engine lubricating oil
What engine variables are sensed by Hydro mechanical fuel control
Power lever position, RPM, compressor inlet pressure temp, burner pressure, or compressor discharge pressure, EGT or TIT
What are the two most commonly used carburetors in small reciprocating engines
Float type carburetor and pressure type carburetor
What type of fuel control unit is used in turbine engines
Hydro mechanical and electronic fuel control units
What is meant by trimming a turbine engine
Adjusting the fuel control for proper idle and full throttle RPM
When should I turbine engine be trimmed
Loss in engine power or the manufacture specifies
What is the purpose of a mixture control in a float type carburetor
Controls the fuel air mixture as air density changes with altitude
What is the function of a metering jet
Limit the fuel flow when the throttle valve is wide open
What is the fuel metering force in a float type carburetor
Differential pressure between the pressure in the float chamber and at the nozzle
Where does a pressure injection carburetor obtain fuel pressure
Boost pump for starting and from the engine driven fuel pump for normal operations
What operates an automatic mixture control (AMC) on a pressure carburetor
Contains sealed Bellows that expand or contract with changes in atmospheric pressure
What is the purpose of filling a pressure injection carburetor full of fuel and allowing it to soak for a period of about eight hours prior to installation
Soften the diaphragms and make them as pliable as they were when the carburetor was originally calibrated
What are three types of carburetor icing
Throttle icing, impact icing, and fuel evaporation icing
What type of fuel pump is generally used with large reciprocating engines
Positive displacement rotary vane type pump
What is the most common type of fuel boost pump
Electrically driven centrifugal type pump
What is the purpose of the bypass valve in the engine driven fuel pump
Provides a path around the pump vanes for starting and allows fuel to bypass the pump in case of pump failure
What are three general causes of vapor lock
Low fuel pressure, high fuel temp, and excessive fuel turbulence
Turbine engine fuel pumps may be divided into what two distinct system categories
Constant displacement and variable displacement
What category is a turbine engine driven gear type pump
Constant displacement
What type of fuel pump can be made to vary the fuel flow at any speed
Variable displacement pump
What part of a gas turbine engine fuel system is very susceptible to the formation of ice
Fuel filter
How is the engine fuel system protected from ice formation
Fuel heaters
Where are fuel filters located
Fuel pump
Can you use automotive gasoline in a reciprocating engine in place of avgas
Yes if you have a STC
What are three major parts of a reciprocating engine induction system
Air scoop, fuel delivery system, and intake manifold
What effect does induction system icing have on engine performance
Cause an engine to act erratically and lose power, and may possibly quit
What engine indication can be the result of a dirty air filter
Low power
What is the purpose of a distribution impeller on a radial engine
Breaks up the fuel globs into finer particles for better distribution to the cylinders
How does an internally driven supercharger get its power
Mechanically engine driven
What is the most common means of regulating the cooling airflow through a reciprocating engine
Use of cowl flaps
What is the purpose of the fins on engine cylinders
Increase the surface area for cooling
What other engine characteristics are designed to aid in the engine cooling besides cooling fins
Cowling and baffles
What is the “open and close” adjustment during installation of cowl flaps important
Keep cylinder head temperature within allowable limits
What publication should be referred to before re-profiling cylinder cooling fins
Manufacturers service, or overhaul manual
What power sources are used to operate cowl flaps
Electrically, hydraulically, manually
What is the purpose of blast tubes
Direct jets of cooling air to accessory‘s of the engine that have high heat concentrations
What are the main reasons that excessive heat in a reciprocating engine is undesirable
Shorten the life of the engine parts, impairs lubrication, and affects combustion
Describe the augmenter system
Help keep the temperature of air cooled engines down by using exhaust gas energy to draw cool air over the engine
What is the source of air directed to engine bearings for cooling
Bleed air
What is the purpose of insulation on the exhaust duct of a turbine engine
Reduce the temperature of the structures in the vicinity and to eliminate the possibility of fuel or oil coming into contact with the hot parts of the engine
What types of materials are used to make insulation blankets for turbine engines
Stainless steel, layers of aluminum full, fiberglass, and silver foil
What areas of a turbine engine are cooled by the secondary air passing through the engine
Combustion chamber and the turbines
What is the purpose of an engine cowling
Streamlines the engine to reduce drag and forms an envelope around the engine, which forces the airstream between the cylinders to cool them
What are two types of reciprocating engine exhaust systems
Short stack system and collector system
What is the purpose of a reciprocating engine exhaust system
Remove heat and noxious gases from the engine nacelle
What happens when lid, zinc, or galvanized marks are made on the exhaust system
Absorbed by the metal when heated causing a change in the molecular structure that weakens the metal
What is the usual cause of muffler and heat exchanger failures
Concentrated areas of thermal stress or vibration stress
Where are exhaust manifold and stack failures most likely to occur
Wells, flanges, or clamped points in the system
What factors are affected if the area of the exhaust nozzle of a turbine engine is changed
Affects both the engine performance and the exhaust gas temp
What is the purpose of a propeller
Create thrust and either pull or push the plane through the air
What are two types of propeller configurations
Tractor type and pusher type
What are the aerodynamic forces and loads acting on a rotating propeller blade
Centrifugal force, aerodynamic twisting, centrifugal twisting, torque bending, and thrust bending forces
What should be used to clean aluminum and steel propeller blades and hubs
Suitable cleaning solvent using a brush or cloth
Why do you put the blades of a counterweight propeller in the high pitch before stopping the engine
In high pitch position the cylinder moves inboard and covers the piston protecting from dirt and moisture in the air
How is feathering accomplished on a constant speed counterweight propeller
Releasing governor oil pressure on the counterweights
What is blade tracking
determining the position of the tips of the propeller blades relative to each other
Why are propellers indexed to the crankshaft of an engine
Reduce vibrations to a minimum
What is the function of an APU air inlet Plenum
Stabilize the pressure of the air before it enters the compressor
When operating at high loads what is the speed of an APU
APU remains at or near rated speed regardless of the load condition
What regulates fuel scheduling during APU start and under varying pneumatic bleed and electrical loads
Maintained automatically by the APU fuel control system
What is the primary function of the load compressor on APUs equipped with a free turbine and load compressor
Bleed air
To prevent rotor seizure “shock cooling” how long should an APU idle before being shut down
3 to 5 minutes
