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251 Cards in this Set
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- Back
- 3rd side (hint)
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What is the purpose of dynamic dampers on crankshafts? |
Reduce engine vibration |
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What types of bearings are generally found in Reciprocating engines? |
Plain, ball, and roller |
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Are connecting rods used in each cylinder of a radial engine the same? |
No. Radial engines use master and articulating rod assemblies |
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Name the different types of piston rings |
Oil control, compression and oil scraper |
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Where should listen ring gaps be installed relative to each other and why? |
Compression ring gaps should be staggered so that they do not align. Prevents excessive blow by |
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What could result from incorrectly installed piston rings? |
Excessive oil consumption |
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What purpose do oil control rings serve? |
Regulate thickness if oil film on cylinder walls |
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What is used to help prevent valve surge or floating in an aircraft engine? |
Two or more springs are used in each valve |
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One engine is equipped with hydraulic valve lifers, what should be the running clearance? |
Zero |
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What is the purpose of valve overlap? |
Better volumetric efficiency and lowers cylinder operating temperatures |
Not looking for better scavenging of exhaust gases. Two other things |
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What indications are given in the event of a leaking or open primer while the engine is running? |
Will not idle properly |
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A cold cylinder is found when troubleshooting a running engine. What does this indicate? |
No combustion in that cylinfer |
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When pulling a propeller through, a hissing sound is heard, indicating valve blow by. What procedure should be performed next? |
A compression check to identify the faulty cylinder |
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What is the purpose of performing a compression test? |
To see if valves, pistons and rings are seated properly |
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When an engine is overhauled, how is its total time affected? |
Total time on engine must be continued and the time since major overhaul is entered into the engine log |
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When an engine is rebuilt, how is its operating history affected? |
If manufacturer rebuilds the engine, it's granted zero time status and is considered to have no previous operating history |
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What inspections should be performed after a propeller strike without sudden stoppage? |
1. Inspect engine mounts, crankcase, nose section for damage. 2. Inspect oil and oil filters/screens for metal particles 3. Inspect the crankshaft or driveshaft for cracks and misalignment |
There are 3 |
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Name some of the precautions that should be performed prior to engine removal |
Disconnect the battery, turn off fuel valves, chock the wheels, and if necessary install a tail stand |
4 things |
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When inspecting a piston, where are cracks most likely to be found? |
In those areas of high stress; base of piston bosses, inside at the junction of the bore and walls, ring lands |
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What does it mean if an engine part is within "serviceable limits"? |
It means that the part is wishing the manufactures limits and can be using in an engine |
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What tools of instruments are used to inspect a cylinder barrel for out of roundness? |
A dial indicator or an inside micrometer is usually used to measure the top of the cylinder and at the skirt. A telescopic gauge and micrometer can be used also. Two reading should be taken 90 degrees from each other |
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How can a loose stud in an engine crankcase be repaired? |
Remove the loose stud and inspect the hole for size and thread condition, may have to use oversize stud or help-coil insert |
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What publication is used to check an engine for normal operation? |
Manufacturers maintenance manual |
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A weak cylinder is found during a compression check. What must be inspected? |
Pressure is transmitted equally in all directions |
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What propose does an oil analysis serve? |
Metal particles in the oil show normal and abnormal wear of the engine. Helps in evaluating the engines internal condition. |
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What inspection should be performed on and engine that has been in storage? |
Perform and inspection to determine if there is any corrosion damage |
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Where would e carburetor air temperature bulb be located? |
In the ram air intake duct |
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What is the fuel pressure range on float type carburetors? |
3-5 psi |
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Where is fuel flow indicating system generally connected within a carbureted reciprocating engine? |
Temperature and atmospheric pressure |
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Where is the fuel flow indicating system generally connected within a carbureted recip engine? |
The transmitter and indicator |
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What unit if measure is generally used to indicate fuel flow? |
Pounds or gallons per hour |
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Why is fuel flow monitored? |
To determine fuel consumption and engine performance |
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What does the manifold gauge indicate and how is it calibrated? |
Measures the absolute pressure in the engine manifold and is calibrated In Inches of mercury |
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What directly controls manifold pressure? |
Throttle opening and engine rpm |
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During engine operations, where should the propeller control be set when checking the manifold pressure? |
Low pitch, high rpm |
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Is the aircraft electrical system required to power a cylinder head temperature gauge |
No. Thermocouple is used as the electrical source |
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What are the possible indications of an oil pressure transmitter or indicator malfunction? |
A severe or sudden drop I. Oil pressure while the oil temperature remains normal and the oil supple remains full |
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What does a tachometer indicate on a reciprocating engine? |
Engine rpm |
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Where should the thermocouple be installed on a reciprocating engine using a single probe cylinder head temperature system? |
In the hottest cylinder |
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Explain the main difference and advantages of turbofan over turbojet engines |
Turbofan engines use a fan to bypass some air around the engine core and to provide thrust. The advantage is that this provides additional thrust without increasing fuel flow |
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Name the components in a gas turbine engine |
Air inlet, compressor section, combustion section, exhaust section, gearbox and accessory section. |
7 things |
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What determines the amount of airflow through a turbine engine? |
The forward speed if the aircraft, compressor speed, air density. |
Three things |
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Name the two types of compressors commonly used in turbine engines |
Axial and centrifugal flow compressors |
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Name the two different methods for attaching turbine engine rotor blades to the rotor disks |
Dovetail, bulb, fir tree |
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What is a split compressor system? |
Also called dual or twin spool compressors, these are connected to the turbine section with two rotor shafts, one inside the other |
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What are the different types of combustion chambers used in turbine engines? |
Can, annular, can-annular, reverse flow annular |
Four types |
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What prevents the combustion chambers from burning? |
Cooling air along the inside of the liner |
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What is the purpose of the interconnecting tubes attached between can-type combustion chambers? |
For flame propagation during start |
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What functions do axial flor turbine nozzles perform? |
They direct the mass airflow to drive the turbine rotor at a specific angle |
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How is thermal stress relieved on a turbine disk? |
By directing bleed air into the face of the disk, Or by grooves being cut in the disk |
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What are carbon seals used for in turbine engines? |
They are used as oil deals for rotor shaft bearings |
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What is shaft horsepower? |
It is an indication of the torque developed by a turboprop or turboshaft engine |
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What do APUs provide? |
They provide ground electrical and pneumatic power for aircraft systems when the engines are not running. Pneumatic power can be used for engine starting, ground heating or air conditioning and antiicing. Many APUs may also be used as an emergency source of I flight electrical power |
Just guessing at question. My booked asked what is the advantage of AC over Dc current. |
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Name the main components of a typical APU |
Small power turbine for power and bleed air, and an electrical generator |
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When is the greatest demand placed on an APU? |
When supplying bleed air |
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How is an APU generally started? |
With its own electrical starter and battery power |
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Where does the APU get its fuel supple from? |
Aircrafts main fuel supply |
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At what speed does a gas turbine APU operate and how is this speed maintained? |
At or near its rated speed regardless of the electrical or pneumatic loads imposed. The APU fuel control automatically adjusts the fuel flow to maintain the rated speed |
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What is used to prevent a heavily loaded APU from exceeding its maximum EGT? |
A load control valve modulated the pneumatics ad to maintain EGTs within limit |
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How is an APU shut down and why is this procedure used? |
After APU is unloaded by closing the bleed air valve, it is run for a specified amount of time to allow the EGT to cool and stabilize. This cool down period is typically three minutes. If a heavily loaded APU is abruptly shut down without any cooling down period, damage could occur as a result of thermal shock |
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What powers the variable inlet guide vanes used on some APUs to regulate compressor intake airflow? |
Fuel pressure |
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What is fan blade shingling? |
The overlapping of the mission shrouds of a fan blade |
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When a turbofan or turbojet engine is shut down, what should a mechanic listen for during coast down? |
Any rubbing sound or other unusual noises from the engine |
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Why are compressor washes performed and what methods are commonly used? |
To remove any contaminants from the compressor section and improve engine performance, fluid was and abrasive grit wash are commonly used |
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How can you tell if a turbofan it turbojet is out of trim? |
High exhaust gas temperature at the target engine pressure ratio for takeoff power |
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Name the different types of compressor blade damage that may be found during inspection |
Dents, cracks, falling, pitting, scratches, burrs, burns, gouges |
8 types |
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What kind of markers can be used to mark the parts in hot and cold sections during repair? |
Layout dye, felt tip marker, chalk |
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How does relative humidity affect turbine engines |
Negligible effect |
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What criteria determines replacement of life limited engine components? |
Cycles, hours and or colander years |
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If turbine blades are removed from turbine disc, why should they be reinstalled in the same location? |
Maintains balance if turbine wheel |
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How are gas turbine engine tachometers calibrated? |
Calibrated in percent rpm |
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On a turbine engine, what is the engine pressure ratio and what does it indicate? |
Ratio between the total inlet pressure and total turbine exhaust pressure and is used to indicate thrust being developed by the engine |
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In a turbine engine, what does exhaust gas temperature, EGT, indicate and how is it obtained? |
EGT is the average temperature of the turbine discharge gasses and is obtained by the thermocouples placed near the turbine exit |
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Can EGT system on a turbine engine be checked without running the engine? |
Yes, by checking the resistance of the thermocouples and circuits |
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Name three components in the induction system of a reciprocating engine. |
Air scoop, carburetor or fuel control, intake manifold |
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What could happen of the induction system becomes obstructed? |
Engine may not be able to produce it's rated power or it may not run at all. This may also be an indication of a dirty air inlet filter |
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How does induction icing affect engine performance? |
It causes a reduction in power and possible erratic operation |
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How is induction icing categorized? |
Impact ice, fuel evaporation ice, throttle ice |
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What is the common method used to prevent induction system ice in a reciprocating engine? |
Raise the temperature of induction air with a preheater |
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What causes fuel evaporation ice? |
Fuel evaporation ice is formed because of the decrease in air temperature resulting from evaporation of the fuel after it is introduced into the air stream |
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What may be the indication of leaking intake pipes? |
The engine runs rough at low rpm |
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What happens to engine power when the carburetor heat is applied? |
There is a noticeable drop in power |
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What could happen if carburetor heat is applied at high engine power settings? |
Detonation |
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What are two types of supercharged induction systems? |
Internally driven and externally driven |
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How and at what point does an internally drive Supercharger boost air pressure? |
An (engine-driven) impeller compresses the fuel/air mixture after it leaves the carburetor |
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What is used to power a turbocharger? |
Engine exhaust gas directed into the turbocharged turbine |
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What could result if the waste gate on a turbocharger system does not close fully? |
The engine may not be able to produce it's rated power at certain altitudes, and the aircraft may not be capable of reaching critical altitude |
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What function does a turbocharger waste gate perform? |
It controls the amount of exhaust gas either into or around the turbocharger, this controlling the boost pressure of the turbocharger |
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What could cause a turbocharger engine to surge? |
There could be a waste gate or controller malfunction |
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What are the common ways to control a waste gate? |
Either mechanically with linkages to the throttle or a separate control, or by an actuator that is driven by oil pressure |
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In a pressurized reciprocating aircraft, what component in the turbocharger system is used to limit the amount of turbocharger airflow used for cabin pressurization? |
Sonic Venturi |
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What is the function of a divergent shaped jet engine inlet during subsonic flight? |
Causes the air velocity to decrease with a subsequent increase in air pressure |
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Where are bell mouth inlet ducts typically found? |
On helicopter engines |
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How do Venturi type particles separated, found in many turbine powered helicopters, function? |
A Venturi is used to accelerate the flow of incoming air and debris through a curved intake. The debris gains too much inertia to allow it to follow the curved intake towards the engine, and is channeled away from the compressor |
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What are the most common methods used for anti-icing if turbine engine inlet ducts? |
Engine bleed air and electrical heating elements |
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What is the purpose of the exhaust system? |
To remove high temperature noxious gases |
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Name two types of reciprocating engine exhaust system |
Short stack, collector system |
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What drawback in using collector type exhaust systems is more than offset when used in turbocharged engines? |
The loss of horsepower due to exhaust system back pressure |
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What could result if the internal baffles or diffusers in an exhaust system fail? |
The flow of the exhaust gasses could be restricted, resulting in a loss of engine power |
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What type of exhaust system is used on turbocharged engines? |
Collector system |
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What kind of material is normally used to make the muffler shrouds found in the exhaust system? |
Stainless steel |
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How do you inspect the internal baffles and diffusers of an exhaust system? |
By disassembling the exhaust system as necessary and visually inspecting the components |
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Why is an exhaust system failure considered a severe hazard? |
It can result in carbon monoxide poisoning, loss of engine power, or fire |
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What could happen if lead, zinc, or galvanized marks are made on an exhaust system? |
They cause a change in molecular structure, which could result in cracks when heated |
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What happens if the heat exchanger leaks exhaust gasses into the induction system? |
There is a loss of engine powet |
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What is an indication of an exhaust gas leak? |
A flat gray or sooty black deposit in the area of the leak |
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Where are the most common places to find cracks in an exhaust system? |
At welded or clamped areas and at the flanges |
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What is a common cause of turbocharger waste gate sticking? |
Coke deposits or carbon buildup |
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Why are turbocharged exhaust system leaked very damaging at high altitudes? |
Pressure differential will cause the leak to escape with torch-like intensity |
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What are exhaust system coke deposits? |
Excessive carbon buildup |
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What is the result of changing the exhaust nozzle area of a turbine engine? |
The engines performance and exhaust gas temperature change |
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Name components of a typical exhaust nozzle |
The tail come, exhaust ducts and support struts |
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What is the purpose of thrust reversers? |
They help decelerate an aircraft after landing |
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How does a noise suppressor found in older turbojet engines work? |
It converts low frequency sound, which is audible over great distance, into high frequency sound, thus reducing the sound footprint |
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What are two most commonly used types of thrust reversers? |
Clamshell, mechanically blocked, or cascade, aerodynamically blocked. |
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How much thrust do the thrust reversers produce compared to the engines full forward thrust? |
Substantially less |
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What are the hazards of operating some thrust reversers at low ground speeds? |
Ingestion of foreign objects stirred up by the exhaust gases and re-ingested of hot exhaust gases |
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What are some of the sources used to heat the fuel in a turbine fuel system? |
Bleed air and engine lubricating oil |
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What are the most common types of fuel metering systems used on small reciprocating engines? |
Float-type carburetors, pressure-injection carburetors and direct fuel injection system |
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What function does the mixture control perform? |
Controls the fuel/air mixture |
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What generally causes spark plug fouling? |
Operating the engine with an excessively rich mixture at idle |
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What is the purpose of an accelerating system? |
It provides an immediate but brief increase in fuel flow in the Venturi to enrich the mixture |
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What is a carburetor economizer system? |
It is a power enrichment system that provides a rich mixture at high power setting, where the excess fuel aids in engine cooling. This system functions at throttle settings above cruise power setting |
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When the mixture is placed in the idle-cutoff position, a slight rise in rpm is noted prior to the engine decelerating. what does this indicate? |
The idle mixture is set correctly |
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Why should engine rpm be accelerated periodically when making carburetor adjustments? |
To clear the engine |
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What maintains the fuel pressure in a pressure-injection carburetor is moved to the idle cutoff positions? |
The engine stops |
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How does an automatic mixture control (AMC) function? |
A sealed brass bellows connected to the fuel metering system, expands and contracts with changes in pressure and temperature, adjusting the mixture accordingly |
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What are some of the advantages of fuel injection system over carburetors? |
Less danger of induction icing, better acceleration, better fuel distribution, better fuel economy, reduced overheating of individual cylinders |
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What purpose do turbine engine fuel control units serve? |
They automatically meter fuel to the engine |
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What are the two basic types of turbine engine fuel control units? |
Hydro mechanical and electronic |
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What are the engine variable detected by the fuel control? |
Power lever position, engine rpm, compressor inlet temperature, compressor inlet pressure, compressor discharge pressure, burner pressure |
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What are the two major components of a supervisory electronics engine control? |
The electronic control unit, computer, and the hydro mechanical fuel control |
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What are some of the advantages of full-authority digital engine control (FADEC) over a hydro mechanical fuel control? |
Better fuel economy, improved starts, requires no engine trimming, provides engine limit protection, provides constant idle speeds regardless of atmospheric conditions or bleed air requirements, fully modulated the active clearance control, and allows more repeatable engine transients |
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What do turbine engine fuel spray nozzles do? |
They inject fuel into the combustion area |
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What are the different engine indications used for trimming a turbine engine? |
Either EPR or rpm is used depending on the particular engine |
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What's maintenance adjustments are normally allowed on an installed hydro mechanical fuel control? |
Specific gravity for fuel, idle rpm and maximum rpm |
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What type of pump can vary the amount of fuel discharged regardless of speed? |
A variable displacement pump |
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What is used to keep water, sediment, and foreign matter out of carburetor? |
The main fuel stainer |
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What is the purpose of a pressure relief valve in. Constant displacement pump? |
It returns excess fuel that is not required by the engine to the inlet side of the pump |
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What type of engine-driven fuel pump is widely used other than gear or piston pumps? |
Rotary vane type |
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What function do fuel boot pumps perform? |
They supply pressurized fuel to the fuel pump, which helps prevent valor lock and cavitation |
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What is a commonly used type of fuel boost pump? |
Centrifugal type |
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What causes vapor lick and why is it a of concern? |
Vapor lock is caused by insufficient fuel pressure, high fuel temperature and excessive fuel turbulence, which may completely block any fuel flow resulting in engine failure |
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What function does the engine-driven pump on a turbine engine perform? |
It provides a continuous supply of fuel at the proper pressure while the engine is running |
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Name the two categories of turbine engine pumps |
Constant and variable displacement |
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What category is a gear-type pump classified in? |
Constant displacement |
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When performing an external inspection of an engine-driven fuel pump, what should you look for? |
Leaks and security of mounting |
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What is the purpose of a shear section of the driveshaft in a dual element constant displacement pump? |
If one element seized, a portion of the driveshaft seizes, allowing the other element to continue to operate |
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Where in a turbine engine fuel system is ice formation likely to occur and how is it prevented? |
The fuel filter is most susceptible to ice formation, so a fuel heater is used that consists of a heat exchanger using either engine oil of bleed air to warm the fuel |
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What is the purpose of a bypass valve in an engine fuel system micron filter? |
It is a safety feature that allows fuel to food to the engine if the filter becomes blocked |
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What is the purpose of a duplex fuel nozzle? |
A duplex fuel nozzle discharges two different spray patterns. The spray pattern is wider durning start up and acceleration and narrows engine speed is increases above idle |
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What are the functions of the pressurizing and dump portions of a pressuring and dump valve? |
The pressurizing proration provides primary and secondary fuel flow to dual-line duplex fuel nozzles, and the dump portion allows fuel to drain from the manifolds after engine shutdown |
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What purpose do fuel selector valves serve? |
They allow tank and engine selection, and provide a means for shutting off fuel flow |
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How can the remaining service life of starter-generator brushes be determined? |
By visually inspecting the amount of wear groove remaining in the brushes |
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What components of the starter-generator require periodic inspection? |
Both commutator and brushes should be inspected for wear beyond operational limits |
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Between field and armature windings in starter-generators, which ordinarily receive current for operation in the start mode? |
Generally, both field and armature receive current for operation in the in the start mode |
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What are possible sources of low pressure compressed air used for starting jet transport aircraft equipped with air turbine staters? |
A ground power unit, an on-board auxiliary power unit, compressed bleed air from an already running engine |
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When should ignition ideally occur? |
A specific number of degrees before the piston reaches top dead center on the compression stroke |
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Why are dual magnetos used in the engine ignition system? |
To improve combustion efficiency, and provide redundancy for safety |
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Why is magneto timing so important? |
For an engine to run properly, the spark plug in a cylinder has to fire at a specific time. To produce the required energy for the spark at the required time, the agents must be in the E-gap position, the breaker points must be starting to open, and the distributor must be electrically aligned with the particular cylinder. If any of these requirements are not correctly adjusted, the engine will run rough or may not run at all. When preparing in a magneto for installation, first the internal timing must be correctly adjusted, then the magneto-to-engine timing is adjusted |
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What function does a magneto perform? |
It produces a high voltage that forces a spark to arc across a spark plug gap |
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Name the components of a high tension magneto system |
Permanent multipole rotating magnet, soft iron core, and pole shoes |
3 things |
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Name the three main circuits of a high tension magneto system |
Magnetic, primary, secondary |
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What is an E-gap angle? |
It is a point a few degrees beyond the neutral position of a rotating magnet where maximum magnetic field stress exist |
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What reduces arcing in the points and also aids the collapsing of the magnetic field in a magneto? |
A capacitor |
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How does a magneto produce the high voltage required to fire a spark plug |
In the rotation cycle, when the magnetic rotor is in the E-gap position, the primary points open, which interrupts the current flow in the primary circuit causing a high rate of flux change in the core, and inducing a pulse of high voltage in the secondary coil |
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What is the P-lead and how does it function? |
The P-lead connects the ignition switch to the primary circuit of the magneto. When the ignition switch is turned off, the P-leads on both magnetos are grounded. When the ignition switch is turned to the left position, the right magneto is grounded, so that only the left magneto operates, and visa versa |
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What is a magneto timing light used for, and what does it indicate? |
It is used for both internal magneto timing and magneto-to-engine timing, and indicates the exact instant the magneto points open |
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Why are turbine engine igniters generally not susceptible to carbon fouling? |
Because the high energy sparks they produce clean off any deposits on the firing end |
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What is the function of a duty cycle in relation to a turbine engine ignition system? |
A duty cycle allows the operation of the ignition system for s given amount of time, and is then followed by a minimum specified cooling down period |
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What are the three main components of a turbine engine system |
Ignition excited, high tension leads, igniters |
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When the engine is operating, what does an ammeter/loadmeter indicating when connected to: 1 battery positive lead? 2. Generator output lead? |
When connected to the battery positive lead, the ammeter indicates whether the battery is charging or discharging. When connected to the generator output lead, it indicates the current produced by the generator, or electrical system load |
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What is done to ensure that each generator shares the load in a multiple generator system? |
Generators are paralleled |
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Where would you find generator rating and performance data? |
On the data plate attached to the generator |
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How is the voltage of a dc generator controlled? |
Three phase alternator |
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How does a voltage regulator control the voltage of an alternator? |
By regulating the voltage output of the dc excited |
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What does the speed of rotation and number of poles if an alternator determine? |
The frequency of the alternator output |
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What are some of the methods used to maintain 400 hertz alternator output frequency in large turbojet or turbofan engines? |
Constant speed drives, integrated drive generators, and variable speed constant frequency power systems |
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Name the major parts of a dc motor |
The armature, field, brushes and frame assembly |
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Name the components of a direct cranking electric stater system |
An electric motor, reduction gears, and automatic engaging and disengaging mechanism |
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Name three types of DC motors |
Series, shunt, compound |
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What type of DC motor is commonly used for a reciprocating engine starter and why? |
A series wound motor is commonly used because it had a high starting torque under heavy load condition |
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What are the operating modes of a turbine engine starting generator? |
It operates first as a starter, then as a generator once the engine is running |
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What is a possible indication when stater drags? |
A dirty or worn starter commutator |
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Where would wore with high temperature insulation material be used? |
When they run close to high temperature areas such as exhaust stacks or heating ducts |
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What is the size standard for electrical wire used in U.S. Manufactured aircraft? |
The American wire gauge |
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How are wire sizes represented? |
By numbered gauge size. The smaller wires are represented by larger numbers. The smallest size wire normally used in aircraft is 22- gauge |
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What is the maximum slack allowed between the supports of a single wire or bundle installation? |
Not over 1/2 inch |
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Why are wires bonded on power plant installations? |
To provide a current return path for electrical accessories, and to prevent static discharge |
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A reciprocating engine is found to have excessive oil consumption without evidence of any oil leaks. What is the likely cause? |
Piston rings are worn or broken |
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What are the functions of lubricating oil in reciprocating engines? |
Reduce friction between moving parts and removed heat |
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Name two important characteristics of aircraft engine oil |
Oil must be light enough to circulate freely yet heavy enough to provide the proper oil film at engine operating teperatures |
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What could happen to an oil that is too low in viscosity at normal engine operating temperature? |
It may become so this that the oil film between moving parts is easily broken, resulting I. Premature wear |
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What are some of the factors must be considered by an engine manufacturer in determining the proper grade of oil for a particular engine? |
Operating load and temperature as well as the rotational speed |
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Why do aircraft reciprocating engines use a relatively high viscosity oil? |
Because they usually have large operating clearances, and operate at high temperatures and pressures |
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Name some oil confaminants |
Metal particles, dirt, carbon, moisture and acids |
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What is a possible indication of low oil pressure together with high oil temperature? |
A low or inadequate oil supply |
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In Ashless dispersant oils, what function does the dispersant perform? |
The dispersant causes sludge-forming materials to repel each other and remain in suspension until they can be trapped by the oil filter or drained. This keeps the oil passages and ring grooves free of harmful deposits, and the inside of the engine clean |
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Why do oil reservoirs have expansion space? |
To provide for oil foaming, thermal expansion, and air in the return oil |
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What could cause oil foaming? |
Diluted oil, contaminated oil, and the oil level being too high |
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What controls oil pressure I a gear-type oil pressure pump? |
Oil pressure relief valve |
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What function does an oil cooler bypass valve perform? |
It directs the oil either through the cooler or around it in order to maintain proper operating oil temperatures |
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What could be a possible indication of the oil cooler passage becomes obstructed? |
High oil temperature |
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Where is the oil temperature bulb usually located? |
At the engine oil inlet |
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What does the presence of metal particles in an engine oil filter indicate? |
Depending on the type and size of the metal particles, this usually indicates abnormal wear and possible engine internal failure |
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What should be done if metal particles are found in an engine oil filter? |
Follow engine manufacturers maintenance instruction |
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Where is the most critical point of lubrication in a gas turbine engine? |
At the turbine bearing |
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What type of oil is used in a turbine engine oil system? |
Synthetic oil |
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Where are oil screens or filters most likely located in a turbine engine oil system? |
At the oil pressure system, main filter, scavenge system, and at or just before the oil jet, last chance |
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Name two types of turbine engine oil coolers |
Air cooled and fuel cooled |
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What could happen to an oil that is too low in viscosity at normal engine operating temperatures? |
It may become so thin that the oil film between moving parts is easily broken resulting in premature wear |
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What effect does excessive heat have on reciprocating engines? |
It shortens the life of the parts, changes the behavior of combustion, and impairs lubrication |
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What is the purpose of cooling fins? |
They provide a larger cooling surface area for removing heat from cylinder heads of air-cooler reciprocating engines. Airflow around the cooling fins transfers the heat from the cylinder heads to the air |
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What are the reasons for using engine cowling, baffled and cowl air seals? |
The cowling performs two main functions: it streamlines the engine area to reduce drag, and is used together with the baffles and cowl air seals to direct airflow over the cylinder for cooling |
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What is the purpose of cowl flaps and how are they operated? |
They are used to control the amount of airflow through the cowling. They are either mechanically, electrically or hydraulically operated |
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How does an augmented cooling system work? |
Outer tube placed over the exiting exhaust gas creates a Venturi effect that draws more airflow over the engine, thus providing additional cooling |
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Where should cowl flaps be positioned for ground operation? |
Fully open |
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What type of power is used to operate cowl flaps? |
Manual, hydraulic, or electrical |
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What should be done when cooling fin damage is discovered? |
Depending on the scope of damage, some cooling fins may be repaired subject to the manufacturers overhaul and repair limitations. If an excessive amount of the cooling fin is broken off, the cylinder should be replaced |
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Why is cowl flap adjustment important? |
The movement must be within tolerances to keep cylinder head temperatures within allowable limits |
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How are turbine engines cooled? |
They are cooled by air passing through the engine. 75% of air passing through the engine is used for cooling which leaves only about 25% for combustion. The air is used to cool the combustion chamber and turbine |
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In a turbine engine, where does bleed air come from that is used to cool beatings and other parts? |
The engine compressor |
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What is the relationship between turbine engine upper temperature limits and power produced? |
The higher the combustion temperatures that an engine can withstand without damage, the more power it is capable of producing |
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What is the approximate percentage of air passing through a turbine engine that is used for cooling rather than combustion? |
Approximately 75% |
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What can be done to effectively allow higher gas temperatures in the turbine section of some engines? |
Compressor bleed air ducted through hollow sections in the turbine inlet guide canes and first stage rotor blades can lower temperatures enough to prevent heat damage |
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What types of fire detector systems are used for engine fire detection? |
Overheat, rate it rise, and flame detectors |
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How does a thermal switch fire protection system operate? |
When heated past a predetermined temperature, the switch closes causing the warning devices in the cockpit to activate |
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How many thermal switches are needed in a thermal switch fire protection system? |
At least one |
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What kind of fire detention system allows more complete coverage than a spot-type system? |
A continuous loop system |
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What happens if an engine equipped with a thermocouple fire warning system overheats slowly? |
Nothing because a fast temperature rise or rapid heating is required for this type of fire system to operate |
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What electrical power is required for a thermocouple fire protection system to operate? |
Both the thermocouple-produced power and the aircraft electrical system are required for this fire protection system to operate |
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What is the likely cause of a false fire warning? |
The engine fire sensing loop is bent or kinked excessively |
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What are fire extinguishing systems designed to do? |
They are designed to dilute the oxygen levels around the engine to a point that does not allow combustion or to reduce temperature below the ignition point |
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How does a kidde fire protection system function? |
Has a sensing element consisting of a sealed Inconel tube containing two conductors that are embedded In a thermistor material. One wore is electrically grounded to the outer tube at each end and acts as an internal ground, and the other is a positive lead. When a fire or overheat occurs the resistance of the thermistor material from, allowing current to flow between the two wires to activate an alarm |
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How does a fenwal continuous loop fire protection system function? |
Used a sensing element consisting of a small diameter flexible Inconel tube containing a single wire electrode surrounded by ceramic beads. These ceramic beads prevent the electrode and tube from touching each other. Current is applied to the electrode while the outer tube is grinned to the aircraft structure. When a fire or overheat occurs, the core resistance of the ceramic bead drops, allowing current to flow between the center electrode and ground, energizing the alarm system |
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What elements must be present for a fire to occur? |
An ignition source such as heat or spark, fuel, oxygen |
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What group of fire extinguishing agents are no longer her manufactured because of environmental concerns? |
Halons were no longer manufactured after 1995. However existing stocks of CFCs may still be used and are subject to strict handling and disposal regulations |
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How are fire extinguishing agents distributed? |
Through perforated tubing and/or discharge nozzles |
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What is the purpose of the discharge and how is it activated? |
The discharge cartridge or squib which eventually ignited, fires a projectile into the des give disk, thereby releasing fire extinguishing agent |
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How is a fire extinguisher system with a high rate of discharge classified? |
As an HRD fire extinguisher system |
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What do the red and yellow discs in a fire extinguishing system indicate? |
A yellow disc is normal discharge
A red disc is thermal discharge |
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How is the fire extinguishing agent in an HRD system distributed, and how long does it take to discharge? |
Agent is distributed through a series of high pressure tubes and takes one to two seconds to discharge |
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What is repurpose of a pressure gauge in a fire extinguishing system? |
Indicates pressure within the container. To check if the pressure is within limits, a pressure-temperature chart is used |
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What is the function of a propeller? |
The propeller blades create thrust to pull or push an airplane through the air |
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What is the difference between a fixed pitch propeller and controllable pitch propeller? |
A fixed pitch propeller is one that has a built in blade angle that cannot be changed by the pilot. These propellers can have blade angle changed by the manufacturer or an approved repair station to optimize performance.- controllable pitch propeller is one that can be changed by the pilots and is usually controlled by a governor that maintains a constant speed. Some controllable propellers also provide reverse pitch and feathering |
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How are some wooden propeller blades protected from wear and damage? |
By metal tipping fastened to the leading edge and tip |
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What happens to the blade angle of a constant speed propeller during a constant power dive? |
The blade angle increases to prevent an over speed |
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What are the functions of a constant speed propeller governor? |
It boosts engine oil pressure before it enters the propeller hub, it senses rotational doped of the propeller, and then adjust the oil flow to the propeller hub to change pitch and therefore speed of the propeller |
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What is the purpose of propeller counterweights? |
Centrifugal force acting on the counterweights causes the blade angle to increase |
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What is meant when a propeller governed is in an onspeed condition? |
The governor is not accelerating it decelerating and the speeder spring and flyweight forces are in balance |
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How is a constant speed feathering propeller feathered? |
By releasing oil pressure in the governor, the counterweights and |
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