AS 356 Final Exam Prep | All HW

62 flashcards · Other · by Nicholas Enoul

HW 1 Q1: What is the principal fluid used for propulsion by most heat engines? (one word)
Answer: Air
HW 1 Q2: Define thrust.
Answer: the force produced by a propeller or by a jet or rocket engine that drives a vehicle (such as an aircraft) forward
HW 1 Q3: The _______ makes the camshaft turn? (one word)
Answer: Crankshaft
HW 1 Q4: 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
Answer: at twice the speed of the crankshaft
HW 1 Q5: What causes the engine's intake and exhaust valves to open? How about to close?
Answer: The rocker arm causes the exhaust valves to open, and the spring closes it. This gif is primitive, but it helps visualize the point. Rocker arm actuates, while springs close by up.
HW 1 Q6: A. For a 4 cylinder horizontally opposed aircraft engine (such as a Lycoming IO-360) how many types of rings are found on a piston? (one number answer) B. What are their names? (one word answers each)
Answer: (A): two (B): Oil and compression NOTE: Even though there are, technically speaking, three rings total, the exam counts the first and second compression rings as a singular type since both are compression rings.
HW 1 Q7: List three types of bearings used in aircraft engines.
Answers: Plain bearing Ball bearing Roller bearing NOTE: Technically speaking, there are many more types of bearings used in an engine (especially turbine ones). However, for the purposes of this exam, I think we only need to know these threee.
HW 1 Q8: What are the advantages fo hydraulic lifters? (short essay)
Answer: Hydraulic lifters reduces or eliminates need for frequent adjustments of valve operating linkages and components. Uses engine oil instead of hydraulic fluid. Note: Hydraulic lifters are the things that actuate your rocker arms and "connect" them to the camshaft lobes. They are also known as "tappets". The special thing about them is that they move along and actually actuate up-and-down in order to move the rocker arm assembly. This is opposed to a regular solid lifter, which is a solid…
HW 1 Q9: Match the parts of a typical cylinder assembly with their function. Cylinder 5 Cylinder Head 2 Intake Valve 3 Rocker Arm 1 Outflow or Exhaust Valve 4 Piston 9 Crank Case 7 Connecting Rod 8 Piston Rings 6
Note: In order to "match" the answers, just type in the associated number from this side to the little boxes you see on the right of the definition. (example. Cylinder 5). The correct answer will be flashed green. To skip this and just see the answer, press "see answer" somewhere below the screen. (1). activates valves (2). covers the upper part of the cylinder (3). separates cylinder from fuel systems/opens to allow fuel & air mixture into the cylinder (4). Allows burned fuel/air mixture out o…
HW 1 Q10: What is the main function of a piston?
Answers: Acts as a moving wall within the combustion chamber Draws in the fuel/air mixture Compress the charge Transfers force to the crankshaft via connecting rod Forces exhaust gases from the cylinder
HW 1 Q11: What three energy forms does the reciprocating engine utilize or convert? (one word for each).
Answers: 1). Chemical 2). Heat 3). Mechanical
HW 1 Q12: Describe the operating cycle of the typical aircraft reciprocating engine.
Answer: Intake, Compression, Combustion, Exhaust Note: When in doubt, remember the old adage. Suck, Squeeze, Bang, Blow.
HW 1 Q13: For a 4 cycle, 4 cylinder horizontally opposed non-geared aircraft engine, how many 'power strokes' will each cylinder have if the engine crank shaft turns 2 full revolutions?
Answer: one Note: the reason this is the cause is because 1 revolution completes two strokes of the engine. If we have four strokes, this is the pattern: -- 1st revolution -- Intakes Compresses then it needs the second to: -- 2nd revolution -- Combustion Exhaust Notice the revolutions and their associated strokes. That means that, with only two revolutions, we only have one combustion (BANG) to produce power with.
HW 1 Q14: A. What is BHP? B. How is it measured?
Answers: A. Brake Horse Power - the indicated horsepower corrected for loss due to friction. B. Indicated HP - Frictional HP
HW 2 Q1: Match the 3 types of engine oils with their description Mineral Oil 3 Ashless Dispersant (AD) 1 Synthetic 2
Note: In order to "match" the answers, just type in the associated number from this side to the little boxes you see on the right of the definition. The correct answer will be flashed in green. (1). Lubricates well and cleans interior of engine. (2). Great in very hot and very cold temperature conditions (3). Lubricates but does not clean. Can create sludge.
HW 2 Q2: Match the following lubricant terms. Flash Point 1 Cloud Point 3 Gravity 2
Note: In order to "match" the answers, just type in the associated number from this side to the little boxes you see on the right of the definition. The correct answer will be flashed in green. (1). When a liquid begins to give off ignitable vapors – can support flame. (2). Comparison measurement of oil and another substance. (3). Temp at which oil’s wax content begins to solidify.
HW 2 Q3: List 4 functions of aircraft engine oil (reciprocating engine).
Potential Answers: 1). Lubricates 2). Cleans 3). Cools 4). Seals 5). Protect (prevents corrosion)
HW 2 Q4: What is viscosity?
Answer: Resistance of a liquid to flow • Low viscosity is thinner liquid (water) • High viscosity is thicker liquid (honey)
HW 2 Q5: Why is viscosity important when selecting lubricant?
Answer: Oil will thicken on a cold day and thin out at high operating temperatures. Need to make sure the oil’s viscosity covers engine operating temperatures to properly lubricate the engine.
HW 2 Q6: What are the advantages of a wet sump system, compared to a dry sump?
Answer: Wet sump is simpler and has less moving parts (no separate tank). No splash feature.
HW 2 Q7: TRUE / FALSE There is a relationship between aviation grade numbers and SAE numbers for lubricating oils.
Answer: FALSE
HW 3 Q1 and Q3: Match the following propeller terms Geometric Pitch 2 Effective Pitch 4 Slip 3 Blade Angle/Blade Pitch 5 Angle of Attack 1
Note: In order to "match" the answers, just type in the associated number from this side to the little boxes you see on the right of the definition. The correct answer will be flashed in green. (1). The angle between the relative wind and chord line (2). The distance the aircraft would move with one full rotation without any slippage. (3). Loss of propeller efficiency (4). The distance the propeller moves when including slippage (5). The angle between the firewall vertical plane and the chord l…
HW 3 Q2: What is the most effective propeller angle of attack for takeoff?
Answer: 2 to 4 degrees
HW 3 Q4: A feathered propeller will have a blade angle of approximately ______ degrees. A. 0° B. 225° Radial from DRK C. 90° D. 45°
Answer: C. 90° Note: 0° is when the blade is directly pointed downwards/upwards.
HW 3 Q5: List and describe 4 forces which act on an operating propeller.
Answers: Centrifugal: throws the rotating blade away from the hub Torque: bends the propeller blades in the direction opposite that of rotation Thrust: bends the propeller blades forward as the aircraft is pushed through the air Aerodynamic Twisting: turns the blades to a high blade angle
HW 3 Q6: Viewing the cross-section diagram of a propeller, identify the blade face and blade back. Label 1: back Label 2: face
Note: Type in the *case accurate* following with the label. The correct answer will flash green once fully typed. Options: back face
HW 3 Q7: On light aircraft, where does the force to operate the propeller pitch changing mechanism come from? (what system/fluid does it use?)
Answer: Engine oil system
HW 3 Q8: Briefly outline the difference in operation for a light single engine and multi-engine aircraft propeller system.
Answers: Single: constant speed, non-feathering Multi: constant speed, feathering
HW 3 Q9: Is the lowest blade angle near the shank or the tip? Why was it built that way?
Answer: Lowest blade angle is near the tip to offset the faster tip speeds. Built that way so propeller lift is constant across the blade.
HW 3 Q10: With a fixed RPM, does the propeller blade angle increase or decrease as airspeed increases? What about the angle of attack?
Answer: Blade pitch angle increases. Blade AoA remains the same. Personal Note: This is unnecessary information, but I thought was aerodynamically cool. In AS 310 Flight Performance, we talked about something called Variable J. Basically, since a propellor is just a moving airfoil, there are two velocities acting with the blade instead of just one with a regular wing. Rotational (i.e. blade moving down/up), and forward (aircraft velocity). If, in this case, airspeed increases and if blade RPM r…
HW 3 Q11: What is the difference between static and dynamic balancing? (note: this is for props)
Answers: Static: a prop suspended by a drawstring Dynamic: electrical machine with vibration analysis of the aircraft
HW 3 Q12: What are the differences between a two-position and a ground-adjustable propeller?
Answers: Two position: permits a change of blade pitch, or angle while the prop is rotating Ground adjustable: operates as a fixed pitch prop, can only be changed when the prop is NOT turning Note: as the definition suggests, two position can only be set into two pre-designed positions. (ex. feather and 90°, but nothing in between).
HW 3 Q13: What component of the governor opposes the force of the speeder springs?
Answer: Flyweights
HW 3 Q14: What forces are used to feather a propeller?
Answer: Mechanical/Spring & Counterweights
HW 4 Q1: Define stoichiometric mixture. (note: what are the ratios?)
Answer: • Air-to-fuel ratio: 15:1 • Fuel-to-air ratio: 0.067:1
HW 4 Q3: What does a carburetor air temperature gauge permit a pilot to do?
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. Note: Here are the bulleted points. Able to apply partial carb heat Potential carb icing Able to tell if you even need carb heat or not
HW 4 Q2: Why is it important for the pilot to know an engine's exhaust gas temperature?
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). Note: Here are the bulleted points. Max power range (think of C172 cruise lean) Recommended operating range Best Economy (again, C172 cruise lean) Adjust based on engine being too hot or too cool
HW 4 Q4: Where are the fuel injection nozzles located on a typical light aircraft engine?
Answer: At the top of the cylinder, near the valves.
HW 4 Q5: In what form does fuel exit the fuel nozzles on a fuel-injected engine? 1). Vaporized 2). Liquid 3). Solid
Answer: 1). Vaporized
HW 4 Q6: The _________ provides the low pressure at the discharge nozzle of a float carburetor.
Answer: Venturi
HW 4 Q7: Why are float carburetors more susceptible to icing? List at least two reasons.
Answers: (1). Aerodynamic cooling because of the decreased pressure through the venturi. (2). Fuel evaporation cooling.
HW 4 Q8: Under what conditions would the use of carburetor heat be detrimental?
Answer: When it is warm and dry outside at low altitude with no ice present, applying carburetor heat would supply less dense air, therefore leading to an RPM drop and making the engine run hotter. Note: another consideration isthat, as far as I know, carb heat sourced air is unfiltered.
HW 4 Q9: When should carburetor heat be used on the ground (note: there are several answers).
Answers: 1). Engine starting during very cold temperatures 2). Prior to shutdown during very cold temperatures 3). High humidity and very cold or warm temperatures
HW 4 Q10: Does the application of carburetor heat richen or lean the mixture? 1). Lean 2). Richen
Answer: 2). Richen Note: the reason is because carb heat would increase the temperature of the intake air. With warmer air, you get less air density. Less dense air + same amount of fuel = richer mix
HW 4 Q11: What are the advantages of the pressure carburetor over float carburetor?
Answers: closed system not as susceptible to icing meters fuel based on mass of air (volume & density automatic mixture control on higher power engines high pressure in fuel system maintained at all times inverted flight is possible Note: The discharge nozzle for fuel is past the venturi for a pressure carb I believe.
HW 4 Q12: What are the functions of the spider? (note: this is for fuel)
Answers: Distributes the fuel evenly to all of the cylinders Shuts off fuel delivery when mixture control is placed to idle cut-off Fuel pressure pushes a valve against the spring and delivers fuel equally to all fuel outlet ports. When fuel pressure reduces, the spring pushes the valve back. No pressure = closed valve.
HW 4 Q13: What are the advantages of a fuel injection system as a fuel metering system?
Answers: 1). Much more even fuel-air mixture distribution among the cylinders. 2). Greater leaning without detonation. 3). Provides continuous flow of fuel into induction system just outside of cylinder.
HW 5 Q1: 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?
Answer: 23.12" Note: Since engine hasn't started (no suction), or if engine is at full RPM (already taking maximum suction), MAP will remain constant. However, since your altimeter setting and actual outside pressure is different, we have to calculate for that. A). We know that pressure decreases -1"Hg / 1000'. Standard is 29.92"Hg at S.L. (0'). B). 7000' * [1"Hg/1000'] = 7"Hg C). 29.92 - 7 = 23.12
HW 5 Q2: What is critical altitude?
Answer: The desired power cannot be maintained above this altitude. I.E. you ran out of throttle. Ex. Your critical altitude is FL180 and you are attempting to cruise FL190. You are trying to maintain 2500RPM, but because of that breach in critical alt, you can only maintain 2400RPM.
HW 5 Q3: Why does MAP increase when RPM Decreased when there is no change in throttle position.
Answer: When RPM decreases, the engine is sucking less air, causing MAP to increase. This is a super helpful vid (time stamp around 12 mins onwards): https://youtu.be/9_rwwfnzZB0?si=ByOkWK6AsqyeisI8
HW 5 Q4: What is the difference between detonation and preignition?
Answer: Detonation: excess fuel and air mixture combusting spontaneously after the power stroke of the engine. Usually engine is overheated or using wrong fuel. Requires spark plugs to be firing. (BOOMS too much). Pre-Ignition: when the fuel-air mixture combusts without the spark plugs firing. It is usually caused by hot leftover carbon in the cylinder. (BOOMS at wrong time).
HW 5 Q5: Which cockpit control will change the MAP on an engine? 1). Throttle Lever (black) 2). Propeller Control Lever (blue)
Answer: 1). Throttle Lever (black)
HW 5 Q6: Which cockpit control will change the RPM on an engine? 1). Throttle Lever (black) 2). Propeller Control Lever (blue)
Answer: 2). Propeller Control Lever (blue)
HW 6 Q1: Define "over boost" for turbocharge engines.
Answer: A state in which too much exhaust is being directed to turbine causing overspeed of turbine rotation. The engine is producing excessive manifold pressure.
HW 6 Q2: Which has the higher operating speed and temperature? 1). Supercharger 2). Turbocharger
2). Turbocharger
HW 6 Q3: A turbocharger compresses: 1). Fuel only 2). Air only 3). Fuel and Air
Answer: 2). Air only
HW 6 Q4: A Supercharger compresses: 1). Fuel only 2). Air only 3). Fuel and Air
Answer: 3). Fuel and Air
HW 6 Q5: Define and describe the function of the following: Ground boost Normally aspirated engine Supercharger Turbocharger Waste Gate
Answers: Ground Boost: aircraft reciprocating engine with a built-in supercharger or turbocharger that boosts the manifold pressure well above sea level pressure to achieve the rated horsepower of the engine Normally Aspirated Engine: No extra performance enhancing device (like a turbo/supercharger) Supercharger: driven mechanically by the engine and compresses both fuel & air down stream of carb. Turbocharger: A free-wheeling exhaust-driven compressor that compresses air only before it reaches…
HW 6 Q6: Describe the function of: Density controller Differential pressure controller (Note: this is for turbos and whatnot)
Answers: Density controller: limits the manifold pressure below critical alitude and regulates bleed oil only at full throttle. Differenital pressure controller: functions during all positions of the waste valve other than fully open position. Acts the same as a density controller - changes bleed oil pressure to control the waste gate.
HW 6 Q7: In an automatic turbocharger, what provides the force to activate the waste gate?
Answers: • Rely on air density and differential pressure controllers to regulate waste gate. • Hydraulic controller opens or closes the waste gate. • When oil pressure increases on the piston, the waste gate valve closes
HW 6 Q8: What is the purpose of an intercooler and how does it work?
Answer: Reduces the temperature of a turbocharger before compressed air reaches the engine. Intercooler acts much like a radiator, only built stronk.
HW 6 Q9: Define "Thermal Shock".
Answer: Large power reductions in very cold air (cruise altitude) with a hot engine may cause engine damage. This can lead to stuck values or cylinder cracks.