AS 356 Exam 1 Prep

64 flashcards · Other · by Nicholas Enoul

What is the principle fluid used for propulsion by most heat engines?
Air Note: "Fuel is incorrect because while fuel is indeed in the process, there is more air than fuel in the cylinder (15:1). As such, air is correct".
Define Thrust
Answers: Forward Force and/or Forward Propulsion
What makes the camshaft turn? (This is a one-word short "essay" question)
Answer: Crankshaft NOTE: Crankshafts are the larger ones, the one that actually connects to the cylinders. Camshafts are the smaller ones with the lobes and interacts with valves. Another way to remember it is that crankshafts are BIG and are CRANKY - they hate their jobs and want to be in bar fights. Camshafts are the smaller ones. Crankshaft: Camshaft:
At what speed does the camshaft turn? 1). At half the speed of the crankshaft 2). At twice the speed of the crankshaft 3). At the same speed of the crankshaft 4). Purple
1). At half the speed of the crankshaft
A). What causes the engine's intake and exhaust valves to open? B). To close? Note: I couldn't really find a way for us to be able to input the answer(s) here. Just give it a good think.
A). Possible Answers: camshafts lobes / lobes rocker arm push rod B): Valve Spring / spring Note: Below is a diagram for easier visualization
A). For a 4 cylinder horizontally opposed engine (like a Lycoming IO-360), how many types of rings are found on a piston? B). What are their names?
A): Two B): compression and oil/lubrication rings Note: technically, I believe that there are three total rings on a typical piston. However, the question wasn't about the amount of rings, but rather, how many types of rings are there. In that case, there would only be two types (oil/compression) This is what I mean, there are three total rings (top compression, second compression, and oil control). However, there are only two types (top/second compression rings & oil ring).
What are the three types of bearings used in aircraft engines?
1). roller 2). ball 3). plain Example of a type of plain bearing: Note: I believe that plain bearings can come in a lot of different versions. The main idea, I gather, is that plain bearings have no extra parts in it (like rollers or balls). It is just the outer/inner rings that interact directly with each other.
What are the advantages of the hydraulic lifters?
Answer: less maintenance, more reliable, more lubricated, and more quiet. Hydraulic Lifter (aka Tappet) Solid lifter Note: this information might not be needed, but I think that the reason why tappets are more reliable than a solid Lifter is because tappets can compress/expand as necessary. A solid Lifter, as the name suggests, is completely solid and can't form along with the lobes. They are also not inherently lubricated like a Tappet. Because of this, solid lifters need to be maintained and…
What is the main function of a piston? (Short-essay question)
Prof answer: Acts as a moving wall within the combustion chamber Draws in the fuel/air mixture Compresses the charge Transfers Force to the crankshaft via connecting rod Forces exhaust gases from the cylinder Note: from what I gather the Prof really just answered that the piston is a moving wall that sucks, squeezes, bangs, and blows --> the 4 cycle process.
What three energy forms does the reciprocating engine utilize or convert?
1). Thermal/heat 2). Mechanical 3). Chemical
Describe the operating cycle of the typical aircraft reciprocating engine.
My Answer: The operating cycle of most reciprocating engines are done in 4 phases: 1). Intake of the fuel/air mixture into the chamber. The piston moves downward as the intake valves open - allowing space for that fuel/air mixture to expand into. 2). Compression of that fuel/air mixture 3). combustion of the chemical energy (now heat energy) caused by that fuel/air mixture, converting it to mechanical energy. Conversion done so by having the piston experience the combustion, pushing that piston…
For a 4 cycle, 4 cylinder horizontally opposed non-geared aircraft engine, how many "power strokes" will each cylinder have if the crank shaft turns 2 full rotations?
Answer: one
What is BHP? How is it measured?
My Answer: BHP is a measurement of power produced from indicated horsepower corrected for frictional losses. Calculated by the following equation: BHP = Indicated HP - Frction HP Note: This question initially seems deceptively complex. We weren't taught how BHP is actually measured. However, I talked to the Prof about it before this homework, and he pretty much stated that he wanted to see the equation and the simple definition.
What are the 4 'strokes' of operation for a 4 cycle reciprocating engines?
1). Intake 2). Compression 3). Combustion 4). Exhaust
Match the 3 types of engine oils with their description. Mineral Oil: 1 Ashless Dispersant (AD): 3 Synthetic : 2
Note: On the green box next to the definition, type-in/match the correct number option associated with the below. Lubricates but does not clean. Creates sludge. Great in very hot and cold temperatures. Lubricates well and cleans interior of engine.
Match the following lubricant terms. Flash Point: 2 Cloud Point: 3 Gravity: 1
Note: On the green box next to the definition, type-in/match the correct number option associated with the below. 1). Comparison measurement of oil and another substance. 2). When a liquid begins to give off ignitable vapors - an support flame. 3). Temp. at which oil's wax content begins to solidify.
What are the 4 functions of aircraft engine oil?
1). Lubricate 2). Cool 3). Clean 4). Seal Note: There is technically a 5th purpose, Protect, but for this class it doesn't seem necessary to know this one (even though one of the correct typed-in options was "prevent corrosion").
What is viscosity? (Short essay question).
My Answer: Viscosity is a liquid's resistance to flow. Low-viscosity fluids (like water) flow very easily. High-viscosity liquids (like cold oil) flow slowly and in a thick fashion.
Why is viscosity important when selecting a lubricant? (Short essay question)
My Answer: If you don't select the correct lubricant, it can create problems as aviation parts were designed for a specific lubricant/oil. Too thick, and the oil might cause blockages - increasing oil pressure and unable to go around the system. Too thin, and the oil may no tbe able to create enough of a film between the surfaces, thusly unable to do its job. It also needs to be used for the right temperatures, as certain oils are designed for operating gin specific temperature ranges. Professo…
What are the advantages of a wet sump system, compared to a dry sump? (Short essay question).
My Answer: Wet sumps are cheaper and simpler in design. Professor Comment/Addendum: And less maintenance required, hence more reliable.
There is a relationship between aviation grade numbers and SAE numbers for lubrication. (True/False)
Answer: False
Match the following propellor terms: Geometric Pitch 3 Effective Pitch 1 Slip 2
Note: type in the correct number corresponding to the answers below. 1). The distance the propellor moves when including slipage 2). The Loss of propeller efficiency 3). The distance the aircraft would move with one full propellor rotation, without any slipage.
What is the most effective propellor angle of attack for takeoff?
Answer: ~2-4 degrees
Match the following propellor angle terms Blade Angle/Blade Pitch 2 Angle of Attack 3
Note: type in the correct number corresponding to the answers below. 1). The angle between the relative wind and rotational velocity vector. 2). The angle between the firewall vertical plane and the chord line 3). The angle between the relative wind and chord line
A feathered propeller will have a blade angle of approximately 90 degrees
Note: please type in the amount of degrees.
List and describe 4 forces which act on an operating propeller. (Short Essay Question)
Note: there are a total of 5 forces acting on a propellor. 1). Centrifigul Force. This is a force that pulls the propellors a part. 2). Torque Bending Force. Bends the prop blades in the opposite direction of spin. 3). Thrust Bending Force. Thrust bends the blades forwards. 4). Aerodynamic Twisting Force. Lift from the bottom of the blade pushes up and twists the blade around the center of rotation. 5). Centrifugal Twisting Force. Greater than and opposite to aerodynamic twisting Force. Tends t…
Note: Fill in the number associated with the definitions below (options are 2 or 1). Blade Face: 2 Blade Back: 1
On light aircraft, where does the force to operate the propeller pitch changing mechanism come from? (Short essay question)
Answer: Engine Oil System
Briefly outline the difference in operation for a light single engine and multi-engine aircraft propeller system. (Short essay question)
Single: Constant Speed-NON Feathering Multi: Constant Speed-FEATHERING Note: The feathering/non-feathering part concerns mid-air engine-shutdowns. In a single engine constant speed aircraft, it doesn't really matter if the prop is feathered or not in an emergency - so it will go immediately to the down position (0 degrees) if there is no more hydraulic/oil pressure. On a multi-engine, though, if one engine fails it will experience asymmetric yaw/thrust. If the failed engine has a non-feathered…
Is the lowest blade angle near the shank or the tip? Why? Was it built that way? (Short essay question)
My Answer: Lowest blade angle is located at the tip of the blade. This is because the tip of the blade experiences a faster airspeed than the root. This was built so as to have a consistent amount of lift on all parts of the propellor. Note: Image below shows that shank area is super twisty, while tip is not twisty.
With a fixed RPM, does the propeller blade angle increase or decrease as airspeed increases? What about the angle of attack? 1). The blade angle increases as airspeed increases and the angle of attack remains the same 2). The blade angle increases as airspeed decreases and the angle of attack remains the same 3). The blade angle remains the same as airspeed increases and the angle of attack decreases 4). The blade angle remains the same as airspeed increases and the angle of attack increases.
1). The blade angle increases as airspeed increases and the angle of attack remains the same
What is the difference between static and dynamic balancing? (Short essay question)
Static Balancing: Static balancing is when you make balancing measures onto a propellor by having it gravity drawn by a draw-string. Dynamic Balancing: Uses electronics and software to measure vibrations induced by the propellor. This is then calculated and the advised balances/weight locations are displayed to the user.
What are the differences between a two-position and a ground adjustable propeller? (Short essay question)
Ground-adjustable props: adjustable with tools and by the user so long as the propellor isn't spinning. Not adjustable mid-air. Two-position props: adjustable in-flight. However, the two-position ones can only be adjusted into two preset angles/pitches.
What component in the governor opposes the force of the speeder spring?
Answer: flyweights
What forces are used to feather a propeller?
Spring/Mechanical & Counterweights
Define 'stoichiometric mixture'? Air-to-Fuel Ratio: Fuel-to-Air Ratio: (choose between 0.067:1 or 15:1)
Air-to-Fuel Ratio: 15:1 Fuel-to-Air Ratio: 0.067:1
Why is it important for the pilot to know an engine's exhaust gas temperature? (short Essay Question)
Answer: Knowing EGT values will help a pilot identify important things such as maximum power range, recommended operating range, and best economy range. Pilots can also adjust the mixture based on if the engine is running too hot or cold (lean or richen).
What does a carburetor air temperature gauge permit a pilot to do? (short essay question)
Answer: With the gauge, a pilot can apply partial carburetor heat instead of just "full" or "none." It can help a pilot detect potential carburetor icing situations, based on humidity and temperature. It also indicates if it is time to apply carburetor heat.
Where are the fuel injection nozzles located on a typical light aircraft engine? (Short Essay)
Answer: At the top of the cylinder, near the valves Potential images below for easier visualization. Top image makes the most sense, bottom one be careful when using.
In what form does fuel exit the fuel nozzles on a fuel-injected engine? 1). Vaporized 2). Liquid 3). Solid
1). Vaporized
The _____ provides the low pressure at the discharge nozzle of a float carburetor. (Fill in the blank)
Answer: Venturi / Venturi Tube
Why are float carburetors more susceptible to icing (at least two reasons)? (Short Essay)
1). Fuel/air vaporization process may bring the total mixture temperature to below freezing. 2). Venturi within the carburetor accelerates the air - which causes a cooling effect and can bring the mixture to below freezing.
Under what conditions would the use of carburetor heat be detrimental? (Short Essay)
Answer: When it's warm and dry at a low altitude with no ice present, applying carb heat would supply less dense air - therefore leading to an RPM drop and making the engine run hotter. Note: Another consideration is that (from what I gathered), carburetor air is unfiltered. This can causes internal damage if FOD was nearby. However, for the purposes of this exam, I am unsure if this is entirely necessary to know.
When should carburetor heat be used on the ground (several answers). (Short Essay)
1). Engine starting with cold OAT conditions to help with fuel vaporization. 2). Before shutting down the engine in cold OAT conditions to prevent thermal shock. 3). Under high-humidity cold/hot conditions.
Does applying carburetor heat richen or lean the mixture? 1). Richen 2). Lean
1). Richen
What are the advantages of the pressure carburetor over the float carburetor? (Short Essay)
1). Closed system 2). Not as susceptible to icing 3). Meters based off of the mass of air (volume & density) 4). automatic mixture control on higher power engines is possible 5). High pressure in fuel system maintained at all times 6). Inverted flight is possible. Note: number (4) is directly caused by (3).
What are the functions of the spider? (Short Essay)
1). Distributes fuel evenly to all the cylinders 2). Shuts off fuel delivery when mixture control is placed in idle cut-off. Note: the below are "advantages" according to the prof, but this is more like how (1) and (2) work. 1B). fuel pressure pushes a valve against the spring and delivers fuel equally to all fuel outlet ports. 2B). When fuel pressure reduces, the spring pushes the valve back. No pressure = closed valve.
What are the advantages of a fuel injection system, as a fuel metering system? (Short Essaaaay)
1). Even distribution of fuel 2). Easier to lean with a lesser chance of detonation 3). Continuous flow of fuel into induction system Note: Even though the assignment itself doesn't say it, fuel injection systems are supposedly "Not subject to icing or high altitude effects" (Fuel Injection Slide p. 6).
Altimeter setting at Flagstaff airport, field elevation 7000 ft is 30.12” Hg. What should MAP be, before engine start and during takeoff with fully opened throttle? (Short Essay)
Answer: 30.12" Hg - 7" Hg (1" Hg/1,000 ft.) = 23.12" Hg Note: if the engine is going full throttle, it might actually be ~22.12"Hg due to a loss caused by the air moving through the air filtration. During normal operations (cruise flight), it should read less than the ambient pressure at cruise altitude.
What is Critical Altitude? (Short Essay)
My Answer: The altitude at which the desired power setting cannot be achieved. Note: this is different from service ceiling. While the critical altitude is one whereby the plane can no longer maintain its altitude, the service ceiling is when the plane can still maintain ~+100fpm or ~+50fpm if I remember correctly.
Why does MAP increase when RPM is decreased when there is no change in throttle position? (Short Essay)
My Answer: As RPM decreases, MAP increases due to the lower suction in the cylinders Note: This is because the MAP is effected by how much the cylinders suck in the air/fuel. If the RPM is super high (with throttle valve remaining in a same position) - the total pressure decreases because the cylinder(s) are sucking in so much air without air being replaced. This also works for the inverse. If the throttle position remains constant, and RPM decreases for whatever reason, then it inherently isn'…
What is the difference between detonation and pre-ignition? (Short Essay)
Pre-ignition is when combustion happens prior to the spark/power stroke - often due to hot spots and unburned carbon inside the cylinder bore. Detonation is when combustion occurs during the power stroke. However, instead of an even controlled burn, it explodes violently outside designed parameters.
Which cockpit control will change the MAP on an engine? 1). Throttle (black lever) 2). Blue lever 3). Mixture
1). Throttle (black lever)
Which cockpit control will change the RPM on an engine? 1). Throttle (black lever) 2). Blue lever 3). Mixture
2). Blue lever
Define ‘over boost’ for turbocharge engines. (Short Essay)
My Answer: When the turbocharger provides too much MAP
Which has the higher operating speed and temperature, a turbocharger or a supercharger?
Answer: Turbocharger. Note: Since it's a free-spinning turbine, it can exceed 100k RPM.
A turbocharger compresses _______________________. (Fill in the blank)
My Answer: atmospheric air that is then sent into the engine.
A supercharger compresses __________________ and ____________________ (carbureted engine). (Fill in the blank)
My Answers: 1). Air (fuel injected) 2). Fuel/air mixture (carbureted engines)
Define and describe the function of the following: Ground boosted engine Normally aspirated engine Supercharger Turbocharger Waste gate (short essay)
Ground Boosted Engine: An engine that uses a mechanical system that compresses air above S.L. pressure (turbocharger/supercharger). Normally Aspirated Engine: An engine that has no performance enhancing components that affect the intake air or fuel/air mixture (like a turbocharger or supercharger) Turbocharger: Mechanical device that compresses the intake air of an engine. Does so by venting exhaust air through a compressor assembly which freewheels and interacts with the intake air. Supercharg…
Describe the function of: Density controller Differential pressure controller (Short Essay)
Density Controller: regulates MAP below critical altitude and regulates bleed oil at full throttle Differential Pressure Controller: Same principles as Density Controller, however functions at all positions of the waste gate - not just fully open.
In an automatic turbocharger, what provides the force to activate the waste gate? (Short Essay)
Answers: 1). Relies on density and differential pressure (controllers) 2). Hydraulic controller opens/closes the waste gate 3). When oil pressure increases on piston, the waste gate valve closes.
What is the purpose of an intercooler and how does it work? (Short Essay)
My Answer: Meant to cool down compressed intake air that had its temperatures increased from high RPM. Does so by using a radiator that uses cool air to decrease compressed air temperature
Define ‘thermal shock’ (Short Essay)
My Answer: When a part expands/contracts unevenly due to sudden temperature changes. Professor Answer + Addendum: Large power reductions in very cold air (cruise altitude) with a hot engine may cause engine damage. This can cause valves to stick or cylinders to crack.
Briefly outline the difference in operation for a light single engine and multi-engine aircraft propeller system. (Short essay question)
Single: Constant Speed-NON Feathering Multi: Constant Speed-FEATHERING Note: The feathering/non-feathering part concerns mid-air engine-shutdowns. In a single engine constant speed aircraft, it doesn't really matter if the prop is feathered or not in an emergency - so it will go immediately to the down position (0 degrees) if there is no more hydraulic/oil pressure. On a multi-engine, though, if one engine fails it will experience asymmetric yaw/thrust. If the failed engine has a non-feathered…