FAA Powerplant Oral Study Guide Questions 2022 (NO ADS)

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Summary

The FAA Powerplant Oral Study Guide 2022 is an essential resource for aspiring aviation mechanics preparing for their oral exams. Created by Chad Meyer, this guide covers detailed questions and answers based on the Jefferson PowerPoint study guide. The transcript dives into topics ranging from reciprocating engines, turbine engine operation, induction systems, lubrication, cooling, and fire protection systems. Each section includes specific technical questions typical of what examinees can expect during oral exams, along with succinct answers, ensuring a thorough review of engine theories and practical mechanical knowledge.

Highlights

Reciprocating engines require dynamic dampers to reduce vibration. 🌟
Compression ring gaps should be staggered to prevent excessive blow-by. 🔧
A leaking primer while the engine runs can stop it from idling properly. 🛑
Turbofan engines are favored for their additional thrust without increased fuel flow. 🚀
Understand how thermal stress is relieved on turbine disks. 🔥

Key Takeaways

Master the essentials of reciprocating and turbine engines for oral exams. ✈️
Understand the significance of proper maintenance and overhaul procedures. 🛠️
Learn about different systems such as induction, cooling, and fire protection. 🌡️
Grasp the importance of accurate fuel metering and lubrication systems. ⛽
Familiarize yourself with troubleshooting methods for various engine issues. 💡

Overview

The FAA Powerplant Oral Study Guide, crafted by Chad Meyer, is a comprehensive guide tailored for those gearing up for aviation oral exams. This detailed transcript covers essential questions derived from the Jefferson PowerPoint study guide focusing on reciprocating engines, turbine engine operations, and more.

Designed to review the core concepts and practical insights into various engine systems, the study guide offers targeted information about fuel metering, lubrication, induction, exhaust systems, and other critical components. With meticulously crafted questions and clear answers, students can effectively prepare for what they'll encounter.

The guide dives into specifics, exploring maintenance, troubleshooting, and the intricacies of modern aviation engines. Knowledge about different engines, such as turbofan and turbojet, and their unique operations is shared thoroughly, equipping students with the know-how to tackle oral exams confidently.

Chapters

00:00 - 02:30: Reciprocating Engines This chapter provides insights into reciprocating engines and features a segment from the Jefferson PowerPoint oral study guide. It includes questions and answers for study, specifically touching on topics like dynamic dampers on crankshafts, which serve the purpose of reducing engine vibration. The chapter also delves into the types of bearings commonly found in these engines.
02:30 - 08:00: Reciprocating Engine Operation, Instruments, Maintenance and Overhaul The chapter discusses the components and operations of reciprocating engines, with a focus on radial engines. It explains that radial engines use master and articulating rod assemblies instead of uniform connecting rods for each cylinder.
08:00 - 15:00: Turbine Engines This chapter discusses the correct installation and function of components in turbine engines, particularly focusing on compression rings and oil control rings. It emphasizes the importance of staggering compression ring gaps to prevent excessive blow-by and oil consumption. Additionally, it explains the role of oil control rings in regulating the oil film thickness on cylinder walls.
15:00 - 21:00: Turbine Engine Operation, Instruments, Maintenance and Overhaul The chapter discusses various aspects of aircraft engines, focusing on valve operations such as preventing surge or floating by using multiple springs on each valve. It explains that on engines with hydraulic valve lifters, the running valve clearance should be zero. Additionally, the chapter elaborates on the purpose of valve overlap.
21:00 - 26:30: Induction Systems The chapter discusses induction systems, focusing on how they improve volumetric efficiency and reduce cylinder operating temperatures. It also touches on reciprocating engine operations, including instruments maintenance and overhaul, and addresses specific troubleshooting indicators, such as issues caused by a leaking or open primer leading to improper engine idling. Additionally, it mentions identifying cold cylinders as part of engine running diagnostics.
26:30 - 34:30: Exhaust Systems This chapter discusses the exhaust systems in engines and provides insights into detecting and diagnosing issues such as valve blowby. It suggests that if a hissing sound is heard when pulling a propeller through, a compression check should be performed. This test is crucial for identifying the faulty cylinder and ensuring that the engine's valves, pistons, and rings are sealing properly.
34:30 - 38:00: Engine Fuel and Fuel Metering This chapter discusses the impact of engine overhauls and rebuilds on the engine's total time and operating history. When an engine is overhauled, its total time accrues, and the time since major overhaul is logged. However, if a manufacturer rebuilds the engine, it receives a zero-time status, indicating no prior operating history. The chapter also touches on inspections that should be performed after these procedures.
38:00 - 45:30: Electrical Starting and Ignition Systems The chapter discusses various inspection protocols following a propeller strike without sudden stoppage. Key inspection areas include engine mounts, the crankcase, the nose section, oil, oil filter screens for metal particles, and the crankshaft or drive shaft for cracks and misalignment. Additionally, the chapter outlines safety precautions prior to engine removal, such as disconnecting the battery, turning off the fuel valves, and securing the wheels.
45:30 - 48:30: Lubrication Systems The chapter on 'Lubrication Systems' begins with a discussion on how to install a tail stand when inspecting a piston. It highlights the areas where cracks are most likely to occur due to high stress, such as the base of piston bosses, inside the junction of the bore and the walls, and the ring lands. The chapter continues to explain what it means when an engine part is within serviceable limits, although the transcript doesn't provide the complete explanation.
48:30 - 55:30: Fire Protection The chapter 'Fire Protection' covers the inspection and maintenance of engine components, specifically the cylinder barrel, for compliance with manufacturer's limits. It emphasizes the use of tools such as dial indicators, inside micrometers, telescopic gauges, and micrometers to check for out of roundness at different points on the cylinder. The text suggests taking measurements at two perpendicular angles to ensure accuracy. It also hints at addressing issues like loose studs in engine cranks.
55:30 - 63:30: Propellers This chapter discusses maintenance procedures for propeller-related issues. It highlights steps to repair loose studs by removing them and inspecting the hole for size and thread condition, suggesting the potential use of an oversized stud or a helicoil insert. It also refers to consulting the manufacturer's maintenance manual to ensure normal engine operation and outlines the importance of inspecting a weak cylinder when it is identified during a compression check.
63:30 - 67:00: Power Plant and Propeller Airworthiness Inspections This chapter covers the importance of conducting airworthiness inspections on aircraft power plants and propellers. It highlights the role of oil analysis in detecting engine wear, which aids in assessing the internal condition of the engine. Additionally, it outlines the necessity of inspecting engines that have been in storage to check for corrosion damage.
67:00 - 67:30: Power Plant Troubleshooting This chapter discusses the troubleshooting of power plants in various contexts. It includes details like the location of the carburetor air temperature bulb, which can be found in the ram air intake duct. Additionally, it covers the typical fuel pressure range for float-type carburetors, which is usually between three to five PSI. The chapter also touches upon the basic components of a fetal indicator system.

FAA Powerplant Oral Study Guide Questions 2022 (NO ADS) Transcription

00:00 - 00:30 the following questions are from the Jefferson PowerPoint oral study guide I will read the question provide a short pause for you to formulate your response and then read the answer chapter one reciprocating engines what is the purpose of dynamic dampers on crankshafts they reduce engine vibration what types of bearings are generally found in reciprocating engines
00:30 - 01:00 plane ball and roller bearings are the connecting rods used in each cylinder of a radial engine the same explain no radio engines use master and articulating Rod assemblies name the different types of piston rings oil control compression and oil scraper where should piston rain gaps be installed relative to each other and why
01:00 - 01:30 compression rain gaps should be staggered so that they do not align this prevents excessive blow-by what could result from incorrectly installed piston rings excessive oil consumption what purpose do oil control Rings serve they regulate the thickness of the oil film on the cylinder walls
01:30 - 02:00 what is used to help prevent valve surge or floating in an aircraft engine two or more Springs are used on each valve on engines equipped with hydraulic valve lifters what should the running valve clearance be zero what is the purpose of valve overlap
02:00 - 02:30 it allows better volumetric efficiency and lower cylinder operating temperatures chapter 2 reciprocating engine operation instruments maintenance and overhaul what indications are given in the event of a leaking or open primer while the engine is running the engine will not idle properly the cold cylinder is found when troubleshooting a running engine what does this indicate
02:30 - 03:00 no combustion in that cylinder when pulling a propeller through a hissing sound is heard indicating valve blowby what procedure should be performed next a compression check should be performed to identify the faulty cylinder what is the purpose of performing a compression test to determine if the valve's pistons and rings are sealing properly
03:00 - 03:30 when an engine is overhauled how is its total time affected when an engine is rebuilt how is its operating history affected the total time on an engine must be continued and this time since major overhaul is entered into the engine log if the manufacturer rebuilds the engine it is granted a zero time status and is considered to have no previous operating history what inspection should be performed
03:30 - 04:00 after a propeller strike without sudden stoppage inspect engine mounts the crankcase and the nose section for damage inspect the oil and oil filters screens for metal particles inspect the crankshaft or drive shaft for cracks and misalignment name some of the precautions that should be performed prior to engine removal disconnect the battery turn off the fuel valves shock the wheels and if necessary
04:00 - 04:30 install a tail stand when inspecting a piston where are cracks most likely to be found in those areas that are highly stretched usually the base of the Piston bosses inside of the junction of the bore and the walls and the ring lands what does it mean if an engine part is within serviceable limits
04:30 - 05:00 it means that the part is within the manufacturer's limits and can be used in an engine does not require replacement what tools or instruments are used to inspect a cylinder barrel for out of roundness the 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 also be used two readings should be taken 90 degrees to each other how can a loose stud in an engine crank
05:00 - 05:30 case be repaired remove the loose stud and inspect the hole for size and thread condition it may be necessary to use an oversized stud or a helicoil insert what publication is used to check an engine for normal operation manufacturer's maintenance manual a weak cylinder is found during a compression check what must be inspected
05:30 - 06:00 pressure is transmitted equally in all directions what purpose does an oil analysis serve metal particles in the oil show Normal and abnormal wear of the engine this helps in evaluating the engine's internal condition what inspection should be performed on an engine that has been in storage perform an inspection to determine if there is any corrosion damage
06:00 - 06:30 where would a carburetor air temperature bulb be located in the ram air intake duct what is the fuel pressure range on float type carburetors three to five PSI Name the basic components of a fetal indicator system
06:30 - 07:00 the transmitter and the indicator what unit of measure is generally used to indicate fuel flow pounds or gallons per hour why is fuel flow monitored to determine fuel consumption and engine performance what does the manifold gauge indicate and how is it calibrated it measures the absolute pressure in the
07:00 - 07:30 engine manifold and is calibrated in inches of mercury what directly controls manifold pressure throttle opening and engine RPM during engine operation where should the propeller control be set when checking the manifold pressure low pitch high RPM is the aircraft electrical system required to power a cylinder head temperature gauge
07:30 - 08:00 no a thermocouple is used as the electrical source what are the possible indications of an oil pressure transmitter or indicator malfunction a severe or sudden drop in oil pressure while the oil temperature remains normal and the oil supply remains full what does a tachometer indicate on a reciprocating engine RPM
08:00 - 08:30 where should the thermocouple be installed on a reciprocating engine using a single probe cylinder head temperature system on the hottest cylinder chapter 3 turbine engines explain the main difference and advantage of turbo fan over turbojet engines the turbofan engine uses a fan to bypass some air around the engine core and to
08:30 - 09:00 provide thrust the advantage is that this provides additional thrust without increasing fuel flow name the major components in a gas turbine engine air Inlet compressor section combustion section turbine section exhaust section gearbox and accessory section what determines the amount of airflow through a turbine engine the forward speed of the aircraft compressor speed and air density
09:00 - 09:30 name the two types of compressors commonly used in turbine engines axial and centrifugal flow compressors name two different methods for attaching turbine engine rotor blades to the rotor discs dovetail type root or bulb type root or fur tree type root what is a split compressor system
09:30 - 10:00 also called dual or twin spool compressors these are connected to the turbine section with two rotor shafts one inside the other what are the different types of combustion Chambers used in turbine engines can annular can annular and reverse flow annular what prevents a combustion Chambers from burning cooling air along the inside of the
10:00 - 10:30 liner what is the purpose of the interconnecting tubes attached between can type combustion Chambers for flame propagation during start what functions do axial flow turbine nozzles perform they direct the mass airflow to drive the turbine Rotor at a specific angle how is thermal stress relieved on a turbine disk
10:30 - 11:00 by directing bleed air onto the face of the disc or by grooves being cut in the disc water carbon seals used for in turbine engines they are used as oil seals for the rotor shaft bearings what is shaft horsepower it is an indication of the torque developed by a turbo prop or turbo shaft engine
11:00 - 11:30 name the main components of a typical APU a small power turbine for power and bleed air and an electrical generator when is the greatest demand placed on an APU when supplying bleed air how is an APU generally started with its own electrical starter and battery power
11:30 - 12:00 where does the Apu get its fuel supply from one of the aircraft's main fuel tanks at what speeds 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
12:00 - 12:30 what is used to prevent a heavily loaded Apu from exceeding its maximum EGT a load control valve modulates the pneumatic load to maintain egts within limits how is an APU shut down and why is this procedure used after the Apu is unloaded by closing the bleed air valve it is run for a specified amount of time to allow the
12:30 - 13:00 EGT to cool and stabilize this cooldown 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 what power is the variable Inlet guide vanes used on some apus to regulate compressor intake airflow fuel pressure what is fan blade shingling
13:00 - 13:30 it's the overlapping of the mid-span shrouds of the fan blade when a turbo fan or turbojet engine is shut down what should a mechanic listen for during code staff any rubbing sound or other unusual noises from the engine chapter 4 turbine engine operation instruments maintenance and overhaul wire compressor wash is performed and
13:30 - 14:00 what methods are commonly used to remove any contaminants from the compressor section and improve engine performance the fluid wash and abrasive grip wash are commonly used how can you tell if a turbofan or turbojet engine is out of trim there will be a high exhaust gas temperature at the Target engine pressure ratio for takeoff power
14:00 - 14:30 name the different types of compressor blade damage that may be found during inspection dents cracks galling hitting scratches Burrs Burns gouges what kind of markers can be used to Mark the parts in hot and cold sections during repair layout die felt tip marker and shock how does relative humidity affect turbine engines
14:30 - 15:00 negligible effect what criteria determines replacement of life-limited turbine engine components Cycles hours and or calendar time if turbine blades are removed from a turbine disk why should they be reinstalled in the same location to maintain the balance of the turban
15:00 - 15:30 wheel our gas turbine engine tachometers calibrated they are calibrated in percent RPM on a turbine engine what is the engine pressure ratio and what does it indicate it is the ratio between the total Inlet pressure and the total turbine exhaust pressure and is used to indicate the thrust developed by the engine
15:30 - 16:00 on a turbine engine what does exhaust gas temperature indicate and how is it obtained EGT the average temperature of the turbine discharge gases and is obtained by thermocouples placed near the turbine exit can the EGT system on a turbine engine be checked without running the engine yes by checking the resistance of the thermocouples and circuits
16:00 - 16:30 chapter 5 induction systems name the three components on the induction system of a reciprocating engine the air scoop carburetor or fuel control and the intake manifold what could happen if the induction system becomes obstructed the engine may not be able to produce its rated power or it may not run at all this also may be an indication of a dirty air inlet filter
16:30 - 17:00 how does induction icing affect engine performance it causes a reduction in power and possible erratic operation how is induction icing categorized as impact ice fuel evaporation ice and throttle ice what is a common method used to prevent induction system ice in a reciprocating engine
17:00 - 17:30 raise the temperature of induction air with a preheater what causes fuel evaporation ice feel the evaporation ice is formed because of the decrease in air temperature resulting from the evaporation of the fuel after it is inducted into the Airstream is carburetor throttle ice more likely to occur at a higher or lower power
17:30 - 18:00 setting why at a lower power setting because the throttle is partly closed offering a larger surface area for ice accumulation what may be the indication of leaking intake pipes the engine runs rough at low RPM what happens to engine power when the carburetor heat is applied
18:00 - 18:30 there is a noticeable drop in power what could happen if carburetor heat is applied at high engine power settings detonation what are two types of supercharged induction systems internally driven and externally driven how and at what point does an internally driven supercharger boost air pressure
18:30 - 19:00 an engine driven impeller compresses the fuel air mixture after it leaves a carburetor what is used to power a turbocharger engine exhaust gas directed onto the turbocharger turbine what could result at the wastegate on a Turbocharger system does not close fully
19:00 - 19:30 the engine may not be able to produce its rated power at certain altitudes and the aircraft may not be capable of reaching critical altitude what function does a Turbocharger wastegate perform controls the amount of exhaust gas either into or around the turbocharger thus controlling the boost pressure of the turbocharger what could cause a turbocharged engine to Surge
19:30 - 20:00 there could be a wastegate or controller malfunction what are the most common ways to control a wastegate either mechanically with linkages to the throttle or a stepper control or by an actuator that is driven by oil pressure and a pressurized reciprocating aircraft what component in the turbocharger system is used to limit the amount of turbocharger airflow used for cabin pressurization
20:00 - 20:30 the Sonic Venturi what is the function of a divergent-shaped jet engine Inlet during subsonic flight it causes the air velocity to decrease with a subsequent increase in air pressure where our bowmoth Inlet ducts typically found on helicopter engines
20:30 - 21:00 how do inventory type particle separators found on 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 what are the most common methods used for anti-icing of turbine engine Inlet
21:00 - 21:30 ducts engine bleed air and electric heating elements chapter 6 exhaust systems what is the purpose of the exhaust system to remove high temperature and noxious gases name two types of reciprocating engine exhaust systems the short stack and The Collector system
21:30 - 22:00 what drawback in using collector type exhaust systems is more than offset when used on turbocharged engines the loss of horsepower due to exhaust system back pressure what could result if the internal baffles or diffusers in an exhaust system fail the flow of the exhaust gases could be restricted resulting in loss of engine power
22:00 - 22:30 what type of exhaust system is used on turbocharged engines The Collector system what kind of material is normally used to make the muffler shrouds found in the exhaust system stainless steel how do you inspect the internal baffles and diffusers of an exhaust system by disassembling the exhaust system as
22:30 - 23:00 necessary and Visually inspecting the components why is an exhaust system failure considered a severe hazard it can result in carbon monoxide poisoning loss of engine power or fire 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
23:00 - 23:30 when heated what happens if the heat exchanger leaks exhaust gases into the induction system there is a loss of engine power what is an indication of an exhaust gas leak flat gray or black deposit in the area of the leak where are the most common places to find cracks in an exhaust system
23:30 - 24:00 at welded or clamped areas and at the flanges what is a common cause of turbocharger waste gate sticking Coke deposits or carbon buildup wire turbocharged exhaust system leaks very damaging at high altitudes pressure differential will cause the
24:00 - 24:30 leak to escape with torch-like intensity water exhaust system Coke deposits excessive carbon buildup what is the result of changing the exhaust nozzle area of a turbine engine the engine's performance and exhaust gas temperature change name the components of a typical turbine exhaust nozzle
24:30 - 25:00 the tail cone exhaust ducts and support struts what is the purpose of thrust reversers they help you celebrate an aircraft after landing how does a noise suppressor found on older turbojet engines work it converts low frequency sound which is audible over great distance into high
25:00 - 25:30 frequency sound thus reducing the sound footprint what are the two most commonly used types of thrust reversers the clamshell or mechanically blocked and the Cascade or aerodynamically blocked how much thrust do the thrust reversers produce compared to the engine's pull forward thrust substantially less
25:30 - 26:00 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-ingestion of hot exhaust gases chapter 7 engine fuel and fuel metering what are some of the sources used to heat the fuel in a turbine engine fuel system the lead air and engine lubricating oil what are the most common types of fuel
26:00 - 26:30 metering systems used on small reciprocating engines flow type carburetors pressure injection carburetors and direct fuel injection systems what function does the mixture control perform controls the fuel layer mixture what generally causes spark plug fouling
26:30 - 27:00 operating the engine with an excessively Rich mixture at idle 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 what is a carburetor economizer system it is a power enrichment system that provides a richer mixture at high power settings where the excess fuel AIDS in engine Cooling this system functions at
27:00 - 27:30 throttle settings above Cruise power settings 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 why should engine RPM be accelerated periodically when making carburetor adjustments
27:30 - 28:00 clear the engine what maintains the fuel pressure in a pressure injection carburetor an engine driven fuel pump what happens if the manual mixture control of a pressure injection carburetor is moved to the idle cutoff position the engine stops
28:00 - 28:30 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 what are some of the advantages of fuel injection systems over carburetor systems less danger of induction icing better
28:30 - 29:00 acceleration better fuel distribution better fuel economy reducing overheating of individual cylinders what purpose do turbine engine fuel control units serve they automatically meter feel to the engine what are the two basic types of turbine engine fuel control units hydromechanical and electronic
29:00 - 29:30 what are the engine variables detected by the fuel control unit power lever position engine RPM compressor Inlet temperature compressor Inlet pressure compressor discharge pressure burning pressure what are the two major components of a supervisory Electronics engine control the electronic control unit computer
29:30 - 30:00 and the hydromechanical fuel control unit what are some of the advantages of a full Authority digital engine control fadec over a hydromechanical fuel control better fuel economy improves starts requires no engine trimming provides engine limit protection provides constant idle speeds regardless of atmospheric conditions or bleed air requirements fully modulates the active
30:00 - 30:30 clearance control and allows more repeatable engine transients what do turbine engine fuel spray nozzles do they inject fuel into the combustion area what are the different engine indications used for trimming a turbine engine either epr or RPM is used depending on the particular engine what maintenance adjustments are
30:30 - 31:00 normally allowed on installed hydromechanical fuel control specific gravity for fuel idle RPM and maximum rpm or maximum epr what type of pump can vary the amount of fuel discharge regardless of speed a variable displacement pump what is used to keep water sediment and
31:00 - 31:30 foreign matter out of the carburetor the main fuel strainer what is the purpose of a pressure relief valve and a constant displacement pump it returns excess fuel that is not required by the engine to the aimless side of the pump the pump what type of engine driven fuel pump is widely used other than gear or Piston Pumps
31:30 - 32:00 a rotary vein type what function do fuel boost pumps perform they Supply pressurized fuel to the fuel pump which helps prevent vapor lock and cavitation what is a commonly used type of fuel boost pump the centrifugal type what causes vapor lock and why is it of
32:00 - 32:30 concern vapor lock is caused by insufficient fuel pressure high fuel temperatures and excessive fuel turbulence which may completely block any fuel flow resulting in engine failure 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
32:30 - 33:00 name the two categories of turbine engine pumps constant and variable displacement what category is a gear type pump classified in constant displacement when performing an external inspection of an engine driven fuel pump what should you look for leaks and security of mounting
33:00 - 33:30 what is the purpose of a Shear section of the drive shaft in a dual element constant displacement pump if one element seizes a portion of the drive shaft seizes allowing the other element to continue to operate where in a turbine engine fuel system is ice formation likely to occur and how is it prevented
33:30 - 34:00 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 or bleed air to warm the fuel what is the purpose of a bypass valve in an engine fuel system micron filter it is a safety feature that allows the field to flow to the engine if the filter becomes blocked what is the purpose of a duplex fuel nozzle
34:00 - 34:30 a duplex fuel nozzle discharges two different spray patterns the spray pattern is wider during startup and acceleration and narrows when the engine speed increases above idle what are the functions of the pressurizing and dump portions of a pressurizing and dump valve the pressurizing portion provides primary and secondary fuel flow to dual line duplex fuel nozzles and the dump
34:30 - 35:00 portion allows fuel to drain from the manifolds after engine shutdown what purpose do fuel selector valves serve they allow tank and engine selection and provide a means for shutting off fuel flow chapter 8 electrical starting and ignition systems how can the remaining service life of starter generator brushes be determined
35:00 - 35:30 by visually inspecting the amount of wear Groove remaining on the brushes what components of the starter generator require periodic inspection both commutator and brushes should be inspected for wear Beyond operational limits between Field and Armature windings and starter generators which ordinarily receive current for operation in the start mode generally both Field and Armature
35:30 - 36:00 receive current for operation in the start mode what are possible sources of low pressure compressed air used for starting jet Transport Aircraft equipped with air turbine starters a ground power unit an onboard auxiliary power unit compressed bleed air from an already running engine when should ignition ideally occur
36:00 - 36:30 a specific number of degrees as determined by the manufacturer before the Piston reaches top dead center on the compression stroke wire dual magnetos used in the engine ignition system to improve combustion efficiency and provide redundancy for safety why is Magneto timing so important
36:30 - 37:00 for an engine to run properly the spark plug in a cylinder has to fire at a specified time to produce required energy for the spark at the required time the Magneto must be in the egap position the breaker points must start to open and the distributor must be electrically aligned with a particular cylinder if any of these requirements are not correctly adjusted the engine will run rough or may not run at all when preparing a Magneto for
37:00 - 37:30 installation first the internal timing must be correctly adjusted then the Magneto to engine timing is adjusted what function does a Magneto perform it produces a high voltage that forces a spark to Arc across a spark plug gap name the components of a high tension Magneto system a permanent multi-pole rotating magnet
37:30 - 38:00 soft iron core and pole shoes name the three main circuits of a high tension Magneto system magnetic primary and secondary 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 exists
38:00 - 38:30 what reduces arcing in the points and also AIDS the collapsing of the magnetic field in a Magneto a capacitor 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 egap position the primary points open which interrupts the current flow in the primary circuit
38:30 - 39:00 causing a high rate of flux change in the core and inducing a pulse of high voltage in the secondary coil 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 vice versa
39:00 - 39:30 what is a Magneto timing light used for and what does it indicate it is used for both internal magnetotiming and Magneto to engine timing and indicates the exact instant the Magneto points open wire turbine engine igniters generally not susceptible to carbon fowling because the high energy Sparks they produce clean off any deposits on the
39:30 - 40:00 firing end 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 a given amount of time and is Then followed by a minimum specified cooling down period what are the three main components of a turbine engine ignition system ignition exciters high tension leads
40:00 - 40:30 igniters when the engine is operating what does an ammeter load meter indicate when connected to One battery positive lead to 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
40:30 - 41:00 what is done to ensure that each generator shares the load in a multiple generator system the generators are paralleled where would you find Generator rating and performance data on the data plate attached to the generator how is the voltage of a DC generator controlled by varying the field current strength
41:00 - 41:30 what is the most common type of alternator used in most aircraft AC systems the three-phase alternator how does a voltage regulator control the voltage of an alternator by regulating the voltage output of the DC Exciter what does the speed of rotation and number of poles of an alternator determine
41:30 - 42:00 the frequency of the alternator output what are some of the methods used to maintain 400 Hertz alternator output frequency on large turbojet or turbofan engines constant speed drives integrated Drive generators and variable speed constant frequency Power Systems name the major parts of a DC motor
42:00 - 42:30 the Armature field brushes and frame assembly name the components of a direct cranking electric starter system an electric motor reduction gears and an automatic engaging and disengaging mechanism name three types of DC motors series shunt and compound what type of DC motor is commonly used
42:30 - 43:00 for a reciprocating engine starter and wide a series 1 motor is commonly used because it has a high starting torque under heavy load conditions what are the operating modes of a turbine engine starter generator it operates first as a starter and as a generator once the engine is running what is a possible indication when a
43:00 - 43:30 starter drags a dirtier worn starter commutator where would wire with high temperature insulation material be used when they run close to high temperature areas such as exhaust Stacks or heating ducts what is the size standard for electrical wire used in U.S manufactured aircraft
43:30 - 44:00 the American wire gauge AWG our wire size is represented by a numbered gauge size the smaller wires are represented by larger numbers the smallest size wire normally used in an aircraft is 22 gauge what is the maximum slack allowed between the supports of a single wire or bundle installation
44:00 - 44:30 not over one half inch wire wires bonded on power plant installations to provide a current return path for electrical accessories and to prevent static discharge chapter 9 lubrication systems the reciprocating engine is found to have excessive oil consumption without evidence of any oil leaks what is the likely cause
44:30 - 45:00 the piston rings are worn or broken what are the functions of lubricating oil and reciprocating engines to reduce friction between moving parts and remove heat name two important characteristics of aircraft engine oil the oil must be light enough to circulate freely yet heavy enough to
45:00 - 45:30 provide the proper oil film at engine operating temperatures 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 what are some of the factors that must be considered by an engine manufacturer in determining the proper grade of oil for a particular engine
45:30 - 46:00 the operating load and temperature as well as the rotational speed 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 name some oil contaminants metal particles dirt carbon moisture and
46:00 - 46:30 acids what is a possible indication of low oil pressure together with high oil temperature a lower inadequate oil supply in ashless dispersant oils what function does the dispersant perform the dispersant causes sludge forming materials to repel each other and remain
46:30 - 47:00 in suspension until they can be trapped by the oil filter or drain this keeps the oil passages and ring grooves free of harmful deposits and the inside of the engine clean why do oil reserves have expansion space to provide for oil foaming thermal expansion and Air in the return oil what could cause oil foaming diluted oil contaminated oil and the oil
47:00 - 47:30 level being too high what controls oil pressure in a gear type oil pressure pump an oil pressure relief valve 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
47:30 - 48:00 what could be a possible indication if the oil cooler passage becomes obstructed a high oil temperature where is the oil temperature bulb usually located at the engine oil inlet what does the presence of metal particles in an engine oil filter indicate depending on the type and size of the
48:00 - 48:30 metal particles this usually indicates abnormal wear and possible engine internal failure what should be done if metal particles are found in an engine oil filter follow engine manufacturers maintenance instruction where is the most critical point of lubrication in a gas turbine engine at the turbine bearing what type of oil is used in a turbine engine oil system
48:30 - 49:00 synthetic oil 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 name two types of turbine engine oil coolers
49:00 - 49:30 air cooled and fuel cooled what could happen to an oil that is too low in viscosity abnormal engine operating temperatures it may become so thin that the oil film between moving Parts is easily broken resulting in premature wear foreign cooling systems what effect does excessive Heat have on reciprocating engines
49:30 - 50:00 it shortens the life of the engine parts changes the behavior of combustion and impairs lubrication what is the purpose of cooling fins they provide a larger cooling surface area for removing heat from cylinder heads of air-cooled reciprocating engines airflow around the cooling fins transfers the heat from the cylinder heads to the air what are the reasons for using engine cowlings baffles and Cal air seals
50:00 - 50:30 the cowling performs two main functions it streamlines the engine area to reduce drag and is used together with the baffles and Cal air seals to direct airflow over the cylinders for cooling what is the purpose of cow flaps and how are they operated they are used to control the amount of airflow through the cowling they are either mechanically electrically or
50:30 - 51:00 hydraulically operated how does an augmentor cooling system work an outer tube placed over the exiting exhaust gas creates a Venturi effect that draws more airflow over the engine thus providing additional Cooling where should Cal flaps be positioned for ground operations fully open what type of power is used to operate calf laps
51:00 - 51:30 manual hydraulic or electrical what should be done when cooling thin damage is discovered depending on the scope of damage some cooling fins may be repaired to subject to the manufacturer's overhaul and repair limitations if an excessive amount of cooling fan is broken off the cylinder should be replaced why is Cal flap adjustment important
51:30 - 52:00 the movement must be within tolerances to keep cylinder head temperatures within allowable limits how are turbine engines cooled they are cooled by air passing through the engine about 75 percent of the Year passing through the engine is used for cooling which leaves only about 25 for combustion this air is used to cool the combustion chamber and turbine
52:00 - 52:30 in a turbine engine where does bleed air come from that is used to cool bearings and other parts the engine compressor 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 is capable of producing what is the approximate percentage of air passing through a turbine engine
52:30 - 53:00 that is used for cooling rather than combustion approximately 75 percent what can be done to effectively allow higher gas temperatures in the turbine section of some engines compressor bleed air inducted through Hollow sections in the turbine in the guide veins and first stage rotor blades can lower temperatures enough to prevent heat damage
53:00 - 53:30 chapter 11 engine Fire Protection what types of fire detector systems are used for engine fire detection overheat rate of rise and Flame detectors how does a thermal switch fire protection system operate when he did pass the predetermined temperature the switch closes causing the warning devices in the cockpit to activate
53:30 - 54:00 how many thermal switches are needed in a thermal switch fire protection system at least one what kind of fire detection system allows more complete coverage than a spot type system a continuous loop system what happens if an engine equipped with a thermocouple fire warning system overheats slowly
54:00 - 54:30 nothing because a fast temperature rise or rapid heating is required for this type of fire system to operate what electrical power is required for a thermocouple fire protection system to operate both thermocouple produce power and the aircraft electrical system are required for this type of fire protection system to operate what is the likely cause of a false fire warning
54:30 - 55:00 the engine fire sensing Loop is bent or kinked excessively 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 temperatures below the ignition point describe how a kitty and fenwall continuous loop fire protection system
55:00 - 55:30 functions a kitty system has a sensing element consisting of a sealed inconel tube containing two conductors that are embedded in a thermistor material one wire 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 drops allowing current to flow between the two wires to activate an alarm
55:30 - 56:00 a fenwall system uses the sensing element consisting of a small diameter flexible in Canal tube containing a single wire electrode surrounded by ceramic beads these ceramic beads prevent the electrode and two from touching each other current is applied to the electrode while the outer tube is grounded to the aircraft structure when a fire or overheat occurs the core resistance of the ceramic beads drops allowing current to flow between the center electrode and ground energizing the alarm system
56:00 - 56:30 what elements must be present for a fire to occur an ignition Source such as heat or spark Fuel and oxygen what group of fire extinguishing agents are no longer manufactured because of environmental concern halons or Freon or chlorofluorocarbons were no longer manufactured after 1995.
56:30 - 57:00 however existing stocks of chlorofluorocarbons may still be used and are subject to strict handling and Disposal regulations our fire extinguishing agents distributed through perforated tubing and or discharge nozzles what is the purpose of a discharge cartridge and how is it activated
57:00 - 57:30 the discharge cartridge or squib which is electrically ignited fires a projectile into the frangible disc thereby releasing fire extinguishing agent how is a fire extinguisher system with a high rate of discharge classified as an hrd fire extinguisher system what do the red and yellow discs and a fire extinguishing system indicate
57:30 - 58:00 a yellow disc indicates a normal discharge a red disc indicates a thermal discharge how is the fire extinguishing agent in an hrd system distributed and how long does it take to discharge the agent is distributed through a series of high pressure tubes and takes one to two seconds to discharge what is the purpose of a pressure gauge in a fire extinguishing system
58:00 - 58:30 indicates pressure within the container to check if the pressure is within limits a pressured temperature chart is used chapter 12 propellers what is the function of a propeller the propeller blades create thrust to pull or push an airplane through the air what is the difference between a fixed pitch propeller and a controllable pitch
58:30 - 59:00 propeller fixed pitch propeller is one that has a built-in blade angle that cannot be changed by the pilot these propellers can have the blade angle Changed by the manufacturer or an approved Repair Station to optimize performance a controllable pitch propeller is one that can be changed by the pilot and is usually controlled by a governor that maintains a constant speed some controllable propellers also provide reverse pitch and Feathering
59:00 - 59:30 how are some wooden propeller blades protected from wear and damaged by metal tipping fastened to the Leading Edge and tip what happens to the blade angle of a constant speed propeller during a constant power dive the blade angle increases to prevent an oversteed what are the functions of a constant speed propeller governor
59:30 - 60:00 thank you it boosts engine pressure before it enters the propeller Hub it senses rotational speed of the propeller and then adjusts the oil flow to the propeller Hub to change pitch and therefore speed of the propeller what is the purpose of propeller counterweights centrifugal force acting on the counterweights causes the blade angle to increase
60:00 - 60:30 what is meant when a propeller Governor is in an on-speed condition foreign ER is not accelerating or decelerating and the speeder spring and flyweight forces are in balance how is a constant speed Feathering propeller feathered by releasing oil pressure in the governor the counterweights and Feathering spring move the propeller
60:30 - 61:00 into feather this happens automatically if the governor oil pressure drops to zero following an engine failure in most turbo crops or can be manually controlled by the pilot by moving the propeller control into the Feathering detent what is an unfathering accumulator it is an oil accumulator used to provide oil pressure to unfather a propeller what is Alpha range and beta range and
61:00 - 61:30 where are they found the alpha Invader ranges pertain to the operating modes of turboprop reversible pitch propellers in the alpha range the propeller is operating the standard constant speed mode which is usually in Flight in the beta range the propeller is operating in the zero or minimum thrust range and negative thrusts or reverse thrust mode which is usually on ground what systems are commonly used for
61:30 - 62:00 propeller ice control fluid alcohol and electrical heat applied to the propeller blade root what propeller repairs can be performed by a Certified mechanic with a power plant rating only minor repairs and alterations can be performed by a Certified mechanic with a power plant rating major repairs must be performed by the manufacturer or
62:00 - 62:30 a certified Repair Station the propeller manufacturer's maintenance manual outlines the scope of repairs our wooden propellers generally cleaned with a brush or cloth and warm water with mild soap where would you find the correct method and technique for cleaning an aluminum propeller and hub the propeller manufacturer's maintenance instructions
62:30 - 63:00 what type of non-destructive testing should be accomplished to a propeller after blending the procedures recommended by the manufacturer what are the two criteria used by many manufacturers to determine the amount of Bend damage that can be repaired by Cold bending of aluminum propellers the extent of the bend and its blade station location how can repair file marks be removed
63:00 - 63:30 from an aluminum propeller with very fine sandpaper when performing a static balance on a two-blade propeller what positions must a propeller be placed in when the measurements are taken vertical and horizontal positions what is a propeller protractor used for it is used to measure propeller blade
63:30 - 64:00 angle what blade conditions can cause engine vibration vibration can be caused by a propeller being out of track and or balanced as well as incorrect blade angle setting what is blade tracking blade tracking is a procedure that compares the position of the propeller blade tips relative to each other
64:00 - 64:30 what controls both manifold pressure and RPM on an engine equipped with a fixed pitch propeller the throttle chapter 13 power plant and propeller airworthiness inspections what Publications can be used as a guide for 100 hour inspections on aircraft engines manufacturers maintenance manuals and far part 43 appendix d
64:30 - 65:00 how do you identify the engine serial number it is on the engine data plate prior to returning a reciprocating engine to service after a 100 hour inspection what operational checks must be performed check the power output static and idle RPM check magnetos fuel and oil pressure check cylinder and oil temperature check
65:00 - 65:30 where are life-limited parts of an engine listed engine maintenance manuals type certificate data sheets and the airworthiness limitations section of the instructions for continued airworthiness where can engine operating limits be found engine manual engine specification type certificate data sheet and aircraft
65:30 - 66:00 manufacturer's maintenance manual why are hot section inspections performed on turbine engines to determine the integrity and wear of the hot section components what inspections must be performed following a turbine engine overseed refer to the engine manufacturer's maintenance manual for the required procedures what inspections must be performed on a
66:00 - 66:30 turbine engine if the exhaust gas temperature exceeds limitations a hot section inspection what FAA approvals are required when installing an engine that is not on the aircraft type certificate a supplemental type certificate or an FAA field approval under what conditions is compliance with an engine service bulletin mandatory
66:30 - 67:00 when an airworthiness director references the service bulletin or when compliance is part of the approved operating specifications for a commercial or air carrier operator when Engine or component overhaul procedures require compliance at time of overhaul chapter 14 power plant troubleshooting what are the possible causes for a turbo jet or turbofan engine having high exhaust gas temperatures low RPM and
67:00 - 67:30 high fuel flow at all engine pressure ratios turbine damage or loss of turbine efficiency due to wear