M15-Jasmine Past Paper PDF

Questions last updated: 22 Mar 2016 No highlight = no reference to when the question last showed up 2003 2004-2005 2006-2009 2010+ 2016 NOTE: Answers that have been checked will have a * and also formatted in the “correct answer” formatting Any other markings are markings that other people made and they assume to be the right answer, but I haven’t checked them That being said, it doesn’t mean my answers are 100% correct. Trust at your own risk. I have taken out all questions that are undated/dated before 2006, because on my exam, about 95% of the questions were questions that I had seen before and they were all within the past 10 years; the other 5% were new questions that I had never seen before. I’m quite sure that if you can find all the correct answers to this set of questions, you will be fine. I try to reference everything but I also get lazy… If there is a dash (point form style), then usually those are my own words. If it looks like a huge block of text copy and pasted, try searching up one of the sentences on google and you might be able to find where it came from. If there is just a page number but no book reference, 99% sure it’s from the HAECO notes Basic Physics 1. What is Newton’s first law called? a. The law of inertia * b. The law of acceleration c. The law of action and reaction 2. If a mass of air is accelerated rearward, according to Newton’s third law: a. There will be rearward reaction b. The magnitude of the force varies with the square of… c. A forward reaction will result * 3. By the third law, the air is push by compressor rearward, thrust is added to a. Rearward b. Forward * 4. When analyzing airflow through an axial compressor, velocity would be regarded as a a. Directional quantity b. Scalar quantity c. Vector quantity * 5. Velocity and speed are often expressed in similar terms, but velocity is determined when: Difference between speed and velocity: a. Direction of an objects movement is detailed * b. The weight of an objected detailed c. A scalar quantity is applied 6. A spring has: a. Potential energy * b. Kinetic energy c. Pressure energy Basic Gas Dynamics 7. Total pressure a. Static + dynamic * b. Ambient + dynamic c. Ambient + static 8. Total pressure as inlet air, the pressure is? a. Increase ram air * b. Decrease ram air c. Forward direction of air flow The ram-air intake works by reducing the intake air velocity by increasing the cross-sectional area of the intake ducting. When gas velocity goes down the dynamic pressure is reduced, while the static pressure is increased. The increased static pressure in the plenum chamber has a positive effect on engine power, both because of the pressure itself and the increased air density that this higher pressure gives 9. Total air pressure measured, static pressure a. Plus ram effect* b. Minus ram effect c. Measured at vertical ……. 10. Airflow through a convergent duct will result in: a. Pressure rise, velocity rise, temperature rise. b. Pressure rise, velocity drop, temperature rise. c. Pressure drop, velocity rise, temperature drop. * -only true for subsonic air flow 11. Diffuser of inlet: a. Pressure rise, temperature rise, velocity drop * 12. Airflow through a divergent duct will result in a. Pressure rise, velocity rise, temperature rise b. Pressure rise, velocity drop, temperature rise * c. Pressure drop, velocity rise, temperature rise -only true for subsonic air flow 13. What is the difference of the aerodynamics between the compressor and turbine area? a. The air flows through a converging passage in the compressor area but the air flows through a diverging passage in the turbine area * 14. Air exiting from the exhaust duct of a choked nozzle, the pressure: a. Below the ambient pressure b. Above the ambient pressure * c. At the ambient pressure As the upstream total pressure is increased above the value at which the propelling nozzle becomes 'choked', the static pressure of the cases at exit increases above atmospheric pressure. 15. If the pressure ratio of an engine is greater than 1.89, the exhaust nozzle speed: In convergent section of a converging-diverging duct, EPR > 1.89: a. Air velocity increases to supersonic b. The density or air will decrease at the throat c. Air velocity stabilizes and increase to Mach 1 * Recall: If P/Po > 0.5283, we have M = 1 somewhere (and the flow is choked) This is the inverse check: if Po/P > 1.89 = 1/0.5283, then M = 1 somewhere 16. Nozzle choked: a. Provide pressure thrust which is affect over the nozzle * b. Overall thrust decreases c. EGT increases and engine performance drops Engines running under choked nozzle conditions derive additional thrust from the excess pressure acting over the propelling nozzle 17. A choked nozzle increases thrust by: a. Increasing the velocity of the exhaust gas to... b. Creating a high pressure when the gas react * c. Preventing the gases from reaching the speed -there are 2 ways of increasing thrust: increase jet velocity or increase pressure difference -jet velocity is increased by afterburning -choked nozzle will increase the pressure difference 18. If more fuel is added to an engine when the exhaust is choked Fuel flow increased with choke exhaust nozzle a. A decrease in the mass airflow and increase... b. An increase in the engine speed and an increase... * c. An increase in the mass flow and a decrease d. --- e. Mass of airflow increase, jet nozzle pressure decrease f.Rpm increase, jet nozzle pressure increase g. Mass of airflow decrease, jet nozzle pressure increase -adding more fuel increases engine speed for sure -choked flow augments thrust using pressure, so I assume the pressure should increase 19. More fuel added after Mach 1 gas velocity is reached: a. Engine speed increases, tail pipe pressure increases * b. Mass flow decreases, tail pipe pressure increases c. Mass flow increases, engine speed decreases Basic Principles 20. The working cycle of turbine engine a. Combustion at constant volume b. Stages of induction, combustion, expansion, exhaust occur intermittently c. Higher flame temperature than piston engine counterparts * -combustion is at constant pressure for turbine engine -stages are intermittent for PISTON engine, while the cycles are continuous for turbine engine (which means that the compressor, combustor, turbine is always working at the same time – it won’t be the compressor working for 2 seconds, then the combustor, then the turbine, etc) -with piston engines, the concern used to be the high pressure spike; with turbine engines, the biggest concern is high flame temperature 21. Gas turbine engine Brayton cycle consist of: a. Two constant volume process and two adiabatics processes b. Two constant pressure (isobaric) process and two adiabatic processes * c. Two isothermal processes and two adiabatic processes Turbofan, Turboprop, Turboshaft, Turbojet 22. The main difference between turbojet and turboprop, turboprop has: a. More turbine stages * b. Less turbine stages c. More compressor stages -turboprop needs more turbine power to drive the huge propeller at the front, so it should have more turbine stages -turbojet only needs to drive the compressor, and the rest of the air is released as hot exhaust For this reason turbo-propeller gas producers tend to have more turbine stages than a conventional gas turbine (pg 520) 23. The design of the modern turbojet engines provide... a. Lower noise levels and increased propulsive efficiency * b. Decreased propulsive efficiency and... c. Higher specific fuel consumption.. Turbofan engines have replaced turbojet engines on most transport and business jet aircraft. The turbofan engine design is quieter and much more fuel efficient. As an example, if a turbojet and a turbofan engine have the same rated thrust, the turbofan engine will burn less fuel because of the greater propulsive efficiency of the fan – Jeppesen TURBINE ENGINES pg 43 24. Increase in aircraft speed causes increase specific fuel consumption for: a. Turbojet engines b. Turboprop engines c. Both turbojet engines and turboprop engines * -specific impulse is 1/TSFC -> specific impulse decreasing means TSFC is increasing -for all engines on this graph, the statement is true, but it is especially true for turbofan engines (and I also assume turboprop) -with TSFC, lower is better -> you want to produce the same amount of thrust with less fuel; however, turboprop engines get more and more inefficient as you get to higher speeds 25. High jet velocity a. Turbofan b. Turbojet * c. Turboprop 26. Bypass flow……. a. Turboprop * b. Turbofan c. Turbojet 27. Turboprop thrust produced by a. Propeller thrust only * b. Propeller thrust + compress bypass c. Propeller thrust + nozzle d. --- e. Propeller f.Exhaust g. Tail pipe 28. Bypass ratio is the ratio of the a. Pressure in the bypass duct to atmosphere pressure b. Pressure at the bypass duct exit to the H.P. compressor exit c. Mass of cool air bypassed through the duct to the mass of hot air (jet air) passed through the core engine * 29. A by-pass ratio 0.7:1 means: a. 0.7lb of air is by-passed for every 1lb taken in b. 0.7Ib of air is by-passed for every 1lb through the HP compressor * c. 0.7lb of air is passed through the HP compressor... pass 30. Engine with by-pass ratio 6:1, it is: a. Low by-pass b. High by-pass* c. Medium/ Intermediate by-pass [Jeppesen Aircraft Gas Turbine Powerplant Page 2-9] Turboprops 31. There are two types design of turboprop; a. Free turbine and single shaft * b. Free turbine and twin spool c. Twin spool and single spool http://www.cast-safety.org/pdf/2_engine_types.pdf 32. A reduction gearbox in a turboprop engine convert: a. High RPM low torque into low RPM, high torque * b. Low RPM low torque into high RPM, high torque c. High RPM into low RPM but no effect to torque 33. The RPM of engine is lower than the propeller, which is achieved by: a. High reduction gearbox * b. Low reduction gearbox Because the propeller needs to rotate at a lower RPM than the turbine, a reduction gearbox reduces the engine shaft rotational speed to accommodate the propeller through the propeller drive shaft. -gear ratio = input speed to output speed 34. Propeller RPM lower than engine, how to achieve: a. Free turbine b. Through planetary reduction gearbox * c. Direct couple with gas generator 35. A special reduction gear for turboprop is mainly: a. Epicyclic * b. Bevel c. Differential 36. Epicyclic gearing is used between shafts which are: a. At right angles to each other in different planes. b. At an angle to each other in the same plane. c. Rotating about a common axis * -the propeller shaft and engine output shaft are aligned (pg 531) Turboshafts (Helicopters) 37. Turboshaft design: a. Axial flow compressor and direct flow b. Axial flow compressor and reverse flow c. Centrifugal compressor and direct flow d. Centrifugal compressor and reverse flow * At even smaller sizes, particularly in turboprop/turboshaft applications, the compression system is either a single centrifugal or has two centrifugal units connected in series (i.e. double-centrifugal). 38. Turboshaft engine (Compressor/ Combustor) a. Impeller / straight b. Impeller / Reversal flow combustor* c. Axial / straight [IVE 15.17 Page 1] 39. Small turboshaft engine commonly uses: a. Centrifugal compressor only b. Axial compressor compressor only c. Both centrifugal and axial compressor* Centrifugal/Axial reverse flow: This idea enables the engine to be as short as possible, thus enabling its installation into small aircraft. (pg 525) 40. In a turboshaft engine the function of the gas producer section is to produce the required energy to the _________. a. Power turbine system * b. First turbine system c. Compressor system 41. Gas producer of turboshaft engine consists of a. Compressor and free turbine b. Power compressor, combustion section and ?? c. Compressor, compressor turbine, power turbine d. Compressor, combustion chamber and compressor turbine * The term gas producer or gas generator is used to denote the parts of the engine that provide the high velocity gases which will drive the propeller: compressor, combustion chamber, compressor turbine 42. Gas generator turboshaft engine extracts ____ of engine from combustion chamber, leaving _____ for turbine: a. 1/3, 2/3 b. 2/3, 1/3 * c. 1/2, 1/2 For a direct drive turbo-prop engine, two thirds (2/3) of the turbine power output is used to drive the compressor, and the remainder of the power left is used to drive the propeller Free Turbine Engine 43. A gas turbine engine, with...drive the compressor is called Turbine directly attached to compressor: a. Directed coupled engine * b. Free-turbine engine (not connected with compressor) c. Power turbine engine The free turbine is an independent turbine that is not mechanically connected to the main turbine. This free turbine, or power turbine, is placed in the exhaust stream -free turbine = power turbine -a direct drive engine should be called a fixed shaft engine 44. Free turbine: a. Turbine to compressor is independent from turbine to reduction gear * 45. Helicopter rotation a. Governed b. Free turbine* 46. A turboshaft engine installed in a helicopter ???? free turbine which can rotate at it's own speed due ??? being? Free turbine type engine, the free turbine independent due to being: A turboshaft engine installed....at its own speed due to being...: a. Gas coupled * b. Mechanically coupled c. Governed In the free turbine engine, there is no direct mechanical connection between the power turbine and the compressor turbine - that is, there is no set of gears connecting them, only a gas path. 47. A free turbine a. Not mechanically connected with Compressor * b. Mechanically connected with Compressor c. Operated on constant speed 48. In the free turbine engine: a. No mechanical connection between compressor and turbine power shaft * b. Compressor is driven by turbine 49. In a free turbine engine a. The air to compressor inlet from turbine b. The compressor and the power output shaft is mechanically connected c. The compressor and the power output shaft is not mechanically connected * Blades 50. Why compressor blades need twist? a. Remain constant axial velocity * b. Allow root to stall first 51. Fan blade twisting is for: a. Maintain constant angle of attack * 52. Why is the number of stator and rotor blades in each stage of a compressor or turbine unequal a. To facilitate manufacture b. To minimize vibration * c. To stabilize operating temperature The ratio between the number of rotating blades and stationary vanes can also be advantageously employed to contain noise within the engine 53. Rotor and stator blades camber orientation a. Facing each other b. Parallel to each other c. Opposite to each other * 54. Stator blades of an axial flow compressor are secured to the: a. Casing using retainer ring * b. Drum using solid root connection c. Casing using fir tree connection The stator blades are again of aerofoil section and are secured into the compressor casing or into stator blade retaining rings, which are themselves secured to the casing. – pg 20 55. In a compressor, stator is secured: a. To the casing using rivets * b. To the drum at root attachment Secured to the casing, uses retaining ring + retaining set screw or shroud ring Stator vanes may be secured directly to the compressor casing or to a stator vane retaining ring, which is secured to the compressor case. -secured to the casing a better answer 56. Methods for retention of compressor blade a. Spot weld at the tip b. Chock at the tip c. Rivet at the tip * 57. Turbine blades are shrouded to: a. Reduce tip loses and improve vibration characteristics * b. Provide a seal for the cooling airflow c. Reduce blade creep 58. Stator a. Fir tree b. Drum root -rotor attachments are usually fixed to the drum root -fir tree slots are common for turbine rotor blades Inlet 59. The blow-in doors in the intake of an engine are used to a. Decrease the air intake on ground b. Increase the air intake on ground * c. Increase the intake air intake in air. d. Increase in air intake to the compressor * Blow-in doors deliver more air to the face of the engine during high thrust operation at low airspeed, such as while making a takeoff – HAECO notes Ch 1-4 pg 153 60. Blow-in door operates when a. High airspeed, low rpm b. Low airspeed, high rpm* c. High airspeed, high rpm The perimeter of the inlet duct has a number of ports to deliver more air to the face of the engine during high thrust operation at low airspeed, such as while making a takeoff. 61. The most efficient air intake of an engine is: Which is the most efficient cowling inlet? a. Mounted on fuselage b. Diameter is minimum and as long as possible c. Large diameter and as short as possible * The length of the duct should be just adequate to accomplish the process of diffusion… The length of the duct then becomes a compromise between a long duct with large friction loss and less turbulence or a short duct with low friction loss and a high order of turbulence and flow separation. – HAECO notes Ch 1-4 pg 161 62. Subsonic aircraft engine inlet: a. Divergent * b. Divergent-convergent c. Convergent-divergent 63. Under supersonic condition, which type will be used for inlet? a. Convergent-divergent type * b. Convergent type c. Divergent-convergent type 64. Super-sonic inlet air a. Slow down the air speed* b. Increase the air speed c. Keep the airflow constantly at sonic speed [Jeppesen Aircraft Gas Turbine Page 3-4] 65. When fitted to a gas turbine engine , the bell mouth inlet: a. Gives a very high aerodynamic efficiency * b. Is susceptible to ‘vena contracta’ effect c. Has retractable skin for takeoff and icing conditions. It is designed with the single objective of obtaining very high aerodynamic efficiency. – HAECO notes Ch 1-4 pg 154 Bell-mouth ducts are used in engine test cells and on engines installed in helicopters. - wiki 66. Bell mouth design of inlet duct is used in: a. Helicopter only b. Slow speed aircraft a. Helicopter, in testing bench and low speed aircraft * [Jeppesen A&P Technician Book Powerplant Page 3-11] 67. In a turboprop engine inlet that has a movable deflector vane..... Deployed position it: a. Assist the engine inlet to supply more air under take-off conditions b. Creates a prominent venturi, which forces sand or ice particles to bypass the engine intake * c. Bypasses excess air from the compressor inlet Another type of separator used on some turboprop aircraft incorporates a movable vane which extends into the inlet airstream. Once extended, the vane creates a more prominent venturi and a sudden turn in the engine inlet. Combustion air can follow the sharp curve but sand or ice particles cannot because of their inertia. The movable vane is operated by a pilot through a control handle in the cockpit. 68. In turboprop, air inlet movable vane is deflected to a. Increase air into compressor at take-off b. Prevent FOD* [Jeppesen A&P Technician Book Powerplant Page 3-72/3-12] 69. Turbine vortex diminisher/dissipater to reduce the: a. Vortex between wing and fuselage………..very close tolerance…….. b. Vortex around the engine casing intake c. Vortex between engine and wing d. --- e. Vortex generated from ….. fuselage-mounted pod-type engine f.Vortex …… wing-mounted engine* g. --- h. Reduce ground vortex for pod-type under wing engine* i. Reduce vortex before engine inlet during flight time j. Reduce vortex for fuselage mounted engine before entry of engine A typical vortex dissipater routes high pressure bleed air to a discharge nozzle located in the lower part of the engine cowl. This discharge nozzle directs a continuous blast of bleed air between the ground and air inlet to prevent a vortex from developing. [Jeppesen Aircraft Gas Turbine Powerplant Page 3-7] 70. Vortex dissipator use when a. Low ground clearance* b. High ground clearance Some gas turbine engine inlets have a tendency to form a vortex between the ground and the inlet during ground operations. This vortex can become strong enough to lift water and debris such as sand, small stones, or small hardware from the ground and direct it into the engine. [Jeppesen Aircraft Gas Turbine Powerplant Page 12] -activated by landing gear switch, because it only turns on when the aircraft is on the ground 71. Hollow IGV is for a. Cooling * b. Oil circulation c. Weight saving d. --- e. To reduce weight f. To pass hot air for ice protection * g. To circulate lubricant On most of these engines, the inlet guide vanes are hollow. This feature is to enable hot anti-ice air, taken from inside the engine, to be circulated through the guide vanes when necessary. – HAECO Chp 1-4 pg 163 Compressor 72. The pressure ratio across a stage of axial flow compressor is about a. 1.2 : 1 * b. 4 :1 c. 2.1 : 1 Across each stage, the ratio of the total pressures of the outgoing air and the inlet air is quite small, being between 1:1 and 1:2 – pg 15 73. The compressor pressure ratio of a single stage centrifugal compressor is normally in the range of? a. 6:1 to 7:1 * b. 2:1 to 3:1 c. 25:1 to 31:1 Typical compression ratios for an axial compressor are in the range of 1.2:1 to 2:1 and 3:1 to 8:1 for a centrifugal stage. 74. If the pressure ratio on each of a two stage axial flow compressor is 1.2:1. The inlet pressure 15psi. What is the discharge pressure? a. 18 PSI b. 21.6 psi * c. 31 psi 15*1.2*1.2 = 26.1 75. The axial compressor: a. The compressor casing is tapered from intake to high pressure compressor * 76. Axial compressor annular casing: a. From first stage taper to compressor outlet 77. For the air in single spool axial flow compressor to maintain a constant velocity while increasing pressure, the a. Excess pressure is bled off b. Inlet guide vanes are adjustable c. Blades get shorter towards the back stages * See figure 3-30 in Jeppesen TURBINE ENGINES (pg 15) 78. A centrifugal flow compressor consists of: a. Impeller and diffuser * b. Inducer and diffuser c. Rotor and inducer The centrifugal flow compressor consists of a rotating impeller and a stationary diffuser manifold – HAECO Ch 1-4 pg 167 79. Axial flow – centrifugal combined type engine, the centrifugal compressor is a. Placed to the LP side b. Placed to the HP side * 80. In the combination of centrifugal and axial flow compressor: a. The centrifugal flow compressor handles low pressure stage b. The centrifugal flow compressor handles high pressure stage * c. Both the centrifugal and axial flow can be used to handles low stages 81. Centrifugal compressor compared to axial flow compressor: a. Fewer component and short rotor shaft. * b. Higher manufacture cost & replacement cost. c. More robust and lower SFC. 82. In comparison with an axial flow compressor, a centrifugal compressor has: a. Small mass flow and lower specific fuel consumption b. Large inlet diameter and higher rotational speed * c. Large mass flow and higher cost 83. Which of the following is an advantage of axial flow compressor over centrifugal flow compressor: a. More robust b. Light weight c. Can attain high pressure ratio with the frontal area * d. Shorter shaft and fewer components e. More blades in each stage of same area the axial compressor engine will also give more thrust for the same frontal area – pg 25 84. Which statement is true for a compressor: a. Shaft is supported by ball bearing * b. Rotor blade and casing tapered toward high pressure end 85. The first stage of blade of compressor is used to : a. Hot gas in the engine intake is cooled by compressor bleed air * b. Electrical heating of leading edge 86. Compressor wash is used when: a. Engine dry motoring * b. Detergent & steam c. Rectify surge and stall -pg 717 87. A desalination compressor wash would normally be carried out at an engine gas generator speed of? a. 80% to 98% b. 58%to 64% c. 14%to 25% * [Jeppesen Aircraft Gas Turbine Powerplant Page 5-5] This is know as a motoring wash and is typically done at speeds that range from 10 to 25 percent 88. Aft of the compressor, air passages: a. Reduce the velocity of the air before it reaches the corr... * b. Increase the velocity of the air before it reaches the co... c. Reduce the pressure of the air before it reaches the... -you want the pressure to be as high as possible when it reaches the combustion chamber, so you make the air go through a diffuser to increase pressure (and hence reduce velocity) Compressor Surge/Stall 89. The cause for a compressor surging is: a. Airflow too low relative to engine rotational speed * b. Airflow too high relative to engine rotational speed c. Airflow separating from the blades on one or more stage As the basic-course of compressor surge is-due to the reduced airflow relative to engine speed that cause an increase in blades' angle of attack. 90. Compressor stall caused by: a. RPM too low b. Angle of attack too low c. Excessive angle of attack * 91. Compressor stall: a. Front of compressor b. Rear of compressor * c. Combustion chamber 92. To prevent low speed stall on compressor: High power at low speed condition: a. Bleed valve close, IGV in max flow position b. Bleed surge open + VIGV at max flow position c. Bleed surge open + VIGV at min flow position* When the engine is stationary or at low rpm, the angle of the VIGV is set at close position (i.e. at a finer pitch) Recovering from stall: as a compressor's rotational speed decreases, the stator vanes are progressively closed to maintain the appropriate airflow angle to the proceeding rotor blades. 93. The engine surge bleed valve is used to a. Minimize the possibility of compressor stall when the engine is operating at a low thrust level * b. Minimize the possibility of compressor stall when the engine is operating at a high thrust level c. Electrically operated 94. The engine surge bleed valves minimize the possibility of compressor stall by a. Bleeding some air away from the compressor when the engine is operating at low rotational speed * b. Bleeding some air away from the compressor when the engine is operating at high rotational speed c. Stopping all bleed air from the compressor when the engine is operating at Intermediate power Surge prevention: Introduce a bleed valve into the middle or rear of the compressor and use it to bleed off excessive air and increase airflow in the front of the compressor at lower engine speeds 95. How does the bleed valve prevent compressor stall? a. Open when engine is at low speed * b. Close when engine is at low speed to provide sufficient air flow c. Open at high speed to keep the air flow 96. Variable inlet guide vanes can be actuated by: a. Electric solenoid b. Fuel pressure and compressor bleed air * 97. Variable inlet guide vane controlled/actuated by signal from a. N1 compressor rpm b. An electrical switch at flight deck c. Fuel pressure or high pressure compressor output * d. Exit of high pressure compressor and ….. 98. VIGV operated by using: a. Fuel * b. Pneumatic 99. Why the bleed air is taken at the early stage of compressor? a. Bleed air at later stage affect thrust * b. Reduce the effect of compressor surge & stall 100. When the exhaust gas exits a choked nozzle, the gas accelerates? a. Radially faster than axially b. To the speed of sound * c. Axially with little radial component -if the nozzle is choked, then M = 1 somewhere in the flow, but if it is a CD nozzle, the gas will continue to accelerate past the speed of sound 101. Engine surge, exhaust gas accelerates: a. High acceleration in radial direction and axial direction b. Small acceleration in radial direction and high acceleration in axial direction c. To the speed of sound * Compressor operates, somewhere between Surge point and Stonewall Point also known as Choking Point. We know what'll happen if flow is decreased, and pressure increases. Its called surge. Now, if flow increases, and discharge pressure decreases, then it means that back pressure experienced by the fluid will be less, i.e. resistance to flow is decreased. Hence, flow increases, and flow velocity increases up to maximum MACH1 i.e. sonic speed. This is very high speed and may cause severe damage to the compressor. This can be prevented by maintaining minimum flow resistance to the fluid flow by providing Anti-choke valves at discharge which closes to restrict the flow and hence preventing Choke. Combustion Chamber 102. Potential energy converted to kinetic energy in combustion chamber by: a. Additional to fuel * b. Compression of air c. Slowing down the air 103. Flame tube in combustion chamber: a. Used to confine and steady the flame b. Lowers the working temperature * c. Ensure complete combustion of kerosene The air not used for combustion, which amounts to about 60 to 75 per cent of the total airflow, is therefore introduced progressively into the flame tube. Approximately half of this is used to lower the gas temperature before it enters the turbine and the other half is used for cooling the walls of the flame tube. 104. Liner in combustion chamber a. Ignition b. Centre of combustion chamber * -the liner is the flame tube, which is where the combustion takes place 105. In combustion chamber, pressure is almost constant because volume is ______ and gas velocity is ______. a. Increase, increase b. Increase, decrease * c. Decrease, increase -for sure, velocity needs to decrease because the incoming speed from compressor is too high Air from the engine compressor enters the combustion chamber at a velocity up to 500 feet per second. But because at this velocity the air speed is far too high for combustion, the first thing that the chamber must do is to diffuse it, (i.e. to decelerate it) and raise its static pressure. -since static pressure is raised, you need something else to compensate for it -> PV = nRT, if you want to lower pressure, need to increase volume; therefore volume increases, overall pressure stays constant 106. From compressor outlet to combustion chamber: a. Velocity increase b. Velocity decrease * c. Pressure increase 107. Toroidal vortex is describing in fuel system? a. Vortex formation on wing tip b. Fuel spray nozzle spraying pattern c. The re-circling station fluid inside combustion chamber * 108. Pre-swirl vane combustion a. Slow airflow * b. Decrease airflow temperature c. Split for 1st and 2nd airflow 109. Swirl vane in a combustion section are designed to: a. Propagate the flame between the combustion area b. Keep the flame off the liners * c. Better air mix and retain combustion * d. Slow the combustion air down which prevents flame out* e. Ensure complete combustion of kerosene -swirl is introduced in the combustion chamber in order to slow down the air, so that it stays in the combustion chamber for a bit longer and therefore the flame is more stabilized 110. The air entering a combustion chamber through swirl vanes is known as? a. The tertiary air b. The secondary air c. The primary air * 111. Secondary air comes from a. Compressor * b. Inlet -pretty much all bleed air comes from the compressor, except for the TCC air which comes from the fan air 112. Can-annular, the secondary air is used for a. Streamline the combusted air b. ?? -secondary air can be used to stabilize the flame, cool the combustion chamber, provide more air for combustion 113. The radial airflow lining in the secondary air at the combustion chamber is used for: a. To assist the combustion, center the flame * Through the wall of the flame tube body, adjacent to the combustion zone, are a selected number of secondary holes through which a further 20 per cent of the main flow of air passes into the primary zone. The air from the swirl vanes and that from the secondary air holes interacts and creates a region of low velocity recirculation. This takes the form of a toroidal vortex, similar to a smoke ring, which has the effect of stabilizing and anchoring the flame 114. In combustion chamber, secondary air is for a. Retard flame front b. Go through swirl vane c. Cool the primary air* 115. The interconnection at the can-annular combustion system is connected between: a. Can to can * b. Can to lining 116. Turbojet engine usually use a. Can annular combustion b. Annular * c. Multiple can 117. Common flame propagation tube in turbofan engine is: a. Can-annular b. Annular * 118. Which combustion system has the highest efficiency? a. Can-annular b. Annular * c. Multiple can Today, annular combustors are commonly used in both small and large engines. The reason for this is that, from a standpoint of thermal efficiency, weight, and physical size, the annular combustor is the most efficient. An annular combustor has the highest efficiency for its weight of any combustor design. However, the engine must be disassembled to repair or replace an annular combustor. Also, the shallow curvature makes this combustor more susceptible to warping. 119. Flame propagation tube is used in what combustion chamber? a. Can type * b. Annular c. (something else that’s wrong) -used to start the engine, only one spark plug is needed in one of the chambers The individual combustors in a typical multiple-can combustion chamber are interconnected with small flame propagation tubes – both can and can-annular need it Multiple can: The separate flame tubes are all interconnected. This allows each tube to operate at the same pressure and also allows combustion to propagate around the flame tubes during engine starting. 120. Turbo shaft engine combustion chamber is usually :\ a. Forward flow and … b. Forward flow and … c. Reverse flow and …. * -reverse flow allows the free shaft to be easily supported 121. The most popular configuration for the combustion ???? a turboshaft engine is? a. Can-annular, through flow b. Annular, through flow c. Annular, reverse flow * 122. Which type of igniter has swirl? a. Duplex b. Simplex c. Both * 123. Duplex nozzle advantage: a. Even distribution b. Can select two detent output * In this way, the Duplex and the Duple burner are able to give effective atomization over a wider flow range than the Simplex burner for the same maximum burner pressure. Also, efficient atomization is obtained at the low flows that may be required at high altitude. 124. Double orifice for: a. Even distribution and rapid burn b. For both low and high thrust * -two orifice for different flow conditions, in both low fuel flow and high fuel flow – better atomization of fuel, because the orifice are calibrated accorrding to pressure 125. Carbon formation on the combustion chamber nozzle: a. Change the flame / fuel ejection angle * b. Create turbulence in the combustion chamber Carbon deposits may block critical air passages, or spray nozzles, which cause distortion of airflow along the liner walls and spray pattern deformation which results in overheating of materials and lower burner life 126. Too fast of acceleration can cause what kind of flame out: a. Lean flame out b. Rich flame out * c. ? There are two types of flameouts, a lean die-out and a rich blow-out. A lean die-out usually occurs at high altitude where low engine speeds and low fuel pressure form a weak flame that can die out in a normal airflow. On the other hand, a rich blow-out typically occurs during rapid engine acceleration when an overly-rich mixture causes the fuel temperature to drop below the combustion temperature or when there is insufficient airflow to support combustion. Lean flame-out: occurs at low fuel pressure, low engine speeds, or in high altitude flight. This sets up a weak mixture which is easily blown out Rich flame-out: Occurs with very fast engine acceleration in which an over-rich mixture causes combustion pressure to increase where compressor airflow stagnates. This interruption of airflow through the combustion chamber cause the flame to extinguish 127. Rich flame out: a. Too much fuel * b. Excessive heat at turbine area c. Too high bulk pressure at combustion chamber 128. A plenum chamber is most likely to be found on an engine fitted with a. An axial flow compressor b. An early types of centrifugal compressor c. A combination of axial and centrifugal compressor * Centrifugal flow compressors have a single or double-sided impeller and occasionally a two-stage, single sided impeller is used, as on the Rolls-Royce Dart. The impeller is supported in a casing that also contains a ring of diffuser vanes. If a double-entry impeller is used, the airflow to the rear side is reversed in direction and a plenum chamber is required -plenum chamber is not limited to early types of centrifugal compressors (still required today), so (c) is probably the best answer -plenum chamber is user to stabilize air pressure before combustion Turbine 129. Turbine blade and turbine disc: a. Statically and dynamically balanced with turbine * b. Integral with blade The disc or wheel is a statically and dynamically balanced unit of specially allowed steel usually containing large percentages of chromium, nickel, cobalt. After forging, the disk is machined all over and carefully inspected using X-rays, sound waves, and other inspection methods to assure structural integrity. 130. Turbine disc definition a. Integral shaft, attachment of turbine blade / It is the integral shaft and the rotor carry the blade * The turbine disc is a machined forging with an integral shaft or with a flange on to which the shaft maybe bolted. The disc also has around its perimeter provision for the attachment of the turbine blades. 131. In an impulse-reaction turbine stage, the reaction portion of the blade is: a. Blade root to mid-span b. At the mid-span c. Mid-span to tip * 132. In the reaction-impulse turbine: a. There are multiple stages, only some of which are impulse turbine b. The turbine blade is reaction at the root and impulse at the tip c. The turbine blade is impulse at the root and reaction at the tip. * 133. For impulse-reaction turbine, the blade a. Extract same KE on the blade surface b. Uniform axial velocity along root to tip* c. 70% impulse, 30% reaction 134. In reaction turbine, the area of stator and rotor a. Divergent, convergent b. Convergent, constant c. Constant, convergent * In a pure reaction turbine, the nozzle guide vanes have parallel air passage which only serves to direct the gas onto the rotor blades at a desired angle. (in practice, they are a bit convergent) The rotor blades form convergent duct passages which accelerate the gas and give rise to a reaction force to drive the turbine 135. A straight (parallel) duct nozzle guide vane would normally be associated with: a. Impulse-reaction turbine blades b. Impulse turbine blades c. Reaction turbine blades * REACTION BLADE: The nozzle guide vanes in a reaction turbine direct the exhaust gas flow to strike the turbine blades at a positive angle of attack. The convergent shape between the turbine blades then increases gas velocity and decreases its pressure to create a component of lift that rotates the turbine wheel 136. What shape of the stator vane when installed before impulse type rotor blade? (N.B: the question does not mention compressor or turbine stage) a. Straight b. Convergent * c. Divergent IMPULSE BLADE: In an impulse turbine system, the turbine nozzle vanes form a series of converging ducts that increase the velocity of the exhaust gases. The impulse turbine blades then extract energy from the gases as the blades redirect the flow of high velocity gases 137. Air exit the combustion stage, and enter the exhaust section the turbine blade a. Impulse and Reaction Type b. Impulse Type * c. Reaction Type The very first stage has to have fixed nozzles, so you may as well have that stage, at least, as an impulse stage. As the gas progresses through the engine, the pressure drops and the velocity of the gas increases. Reaction engines work better as the propellant velocity increases - which may explain why the low pressure stages use reaction. The earlier stages, possibly have to use impulse because the velocity is too low for reaction to work well. -the first stage is sometimes pure impulse stage, but otherwise impulse + reaction is also a fair answer 138. Turbine blade un-twist is cause by? a. Blade erosion b. Gas loads on the blade surface * c. A high torque loading on the blade. [Jeppesen A&P Technician Book Powerplant Page 4-31] Loads imposed by the flow of gases across turbine blades and vanes can cause them to untwist 139. A fir-tree root turbine blade attachment? a. Locates the blade radially b. Locates the blade axially * c. Allows a limited amount of axial movement The blade is kept from moving axially either by rivets, locking tabs or devices, or another turbine stage. The base, or root of a rotor blade often fits loosely into the rotor disk. This loose fit allows for easy assembly and vibration damping. As the compressor rotor rotates, centrifugal force keeps the blades in their correct position, and the airstream over each blade provides a shock absorbing or cushioning effect. -the limited amount of movement should be in the radial direction? 140. The rotor blade is locked by a. Located axially * b. Located radically 141. Retention of a fir-tree mounted turbine blade ????? In the groove on a disk is by? Rotor blades are locked in the Fir tree root: For turbine Fir-tree blades, what is used to secure the blades? a. Spot welding b. The use of a grub screw c. Using a rivet or locktab * 142. Turbine blade under fixed stress, service life is: a. Deteriorate significantly when operated slightly over temperature * b. Dependent on blade cooling only c. It’s relatively constant From the foregoing, it follows that for a particular blade material and an acceptable safe life there is an associated maximum permissible turbine entry temperature and a corresponding maximum engine power. It is not surprising, therefore, that metallurgists and designers are constantly searching for better turbine blade materials and improved methods of blade cooling. -the service life of a blade is defined by how much it is allowed to elongate, and this will happen faster when exposed to extreme temperatures over its limit 143. The turbine inlet guide vane and first stage rotor blade is normally cooled by? a. Transpiration cooling with bleed air b. Bleed air film cooling * c. Cooling the hot gases before they strike the vanes and blades / Convection cooling In film cooling, cool air is bled from the compressor stage, ducted to the internal chambers of the turbine blades, and discharged through small holes in the blade walls 144. Porous turbine blade cooling is called: a. Transpiration cooling with bleed air * b. Bleed air film cooling c. Cooling the hot gases before they strike the vanes and blades / Convection cooling Transpiration cooling = It is similar to film cooling in that it creates a thin film of cooling air on the blade, but it is different in that air is "leaked" through a porous shell rather than injected through holes. In addition to drilling holes in a turbine vane or blade, some nozzle vanes are constructed of a porous, high-temperature material. In this case, bleed air is ducted into the vanes and exits through the porous material. This type of cooling is known as transpiration cooling and is only used on stationary nozzle vanes. 145. Cooling turbine nozzle vane by transpiration is only used on: a. Non-segment shroud b. Shrouded turbine blade c. Stationary turbine nozzle guide vane * 146. When air passes through nozzle guide vane a. Velocity increase, pressure decrease * b. Velocity decrease, pressure increase c. Velocity increase, pressure increase 147. The stator vanes of a turbine are used to a. Decrease the velocity, increase the pressure b. Increase the velocity, decrease the pressure * c. Decrease the velocity, increase the pressure 148. Hollow NGV, cool air from: a. Compressor * 149. The primary reason for a limitation being imposed on the temperature of gas flow is to: a. Prevent damage to the jet pipe by overheating b. Ensure that the maximum acceptable temperature at the turbine blades is not exceeded * c. Prevent overheating and subsequent creep.. 150. For a gas turbine engine, the turbine overheat can: Over-temperature of turbine: a. Causes a serious fire risk. b. Requires immediate stoppage of the engine like an engine fire. * c. Is an essential warning because no fire extinguishant discharges into the turbine area Turbine overheat does not constitute a serious fire risk. Detection of an overheat condition, however, is essential to enable the pilot to stop the engine before mechanical or material damage results.– RR pg 167 In case of a tailpipe fire: Following the engine fire drill will have no effect as the fire agent is discharged outside of the engine core. Additionally, activation of the engine fire emergency sequence may negate the ability to dry crank the engine. -so fire extinguishant does get discharged into the core of the engine 151. Temperature control a. Prevent tailpipe overheated (Wrong. Lai Sir: many fish.) b. Prevent NGV overheated then creep c. Prevent turbine blade temperature excess acceptable limit. * Creep / Growth 152. To reduce “blade growth” due to high rotational speed: a. Absorbed by turbine shroud b. Reduced by using reaction turbine blade c. Limit the use of turbine shroud * However, because of the added weight, shrouded turbine blades are more susceptible to blade growth 153. Creep of turbine blades is caused by: a. Prolonged idling at low rev/min b. Application of heat whilst under centrifugal loading * c. Bending stresses set up by gas pressure 154. Blade creep in the turbine will result in a. Increased turbine vibration b. Loss of thrust c. Increased turbine diameter * 155. For uneven creep of turbine, what did the engine experience? a. Hot start b. Over stress on the turbine blade * c. Overspeed 156. Turbine creep is a: a. ? b. Plastic and irreversible process * c. Time elapsed to failure to definite and predictable 157. Turbine creep: a. High temperature + high rotational speed b. High temperature + long operation time 158. Prevent turbine creep by: a. Keep maximum exhaust temperature b. Keep minimum exhaust temperature * c. Minimum inlet temperature 159. Turbine blade creep at a small and constant rate at what stage? a. Tertiary stage b. Secondary stage * c. Primary stage 160. Tertiary creep is due to: a. Hot start/Over temperature * b. Too many engine cycles c. Too much load on the blade surface Tertiary creep is a third stage which occurs at an accelerated rate after a period of secondary creep. The onset of tertiary creep is attributed to hot starts, overtemperature events, extended operation at high power settings, and blade erosion. [Jeppesen A&P Technician Book Powerplant Page 4-31] Nozzle 161. The exhaust of turbojet engine is usually : a. Always nozzle * b. Always convergent duct c. Includes diffuser and followed by nozzle -a nozzle is not defined by its shape, but rather by a duct that will cause velocity to increase and pressure to decrease -turbojet uses jet thrust, so jet velocity must increase 162. Reduce exhaust nozzle area: a. Affect exhaust pressure b. Affect exhaust temperature * c. Turbine expansion ratio change Exhaust (jet) nozzle area should not be altered in the field because any change in the area will change both the engine performance and the exhaust gas temperature. 163. For a variable exhaust nozzle, what changes when the nozzle area is decreased? a. EGT * b. Turbine expansion ratio c. Exhaust gas pressure 164. For modern variable area exhaust nozzle: a. The nozzle is wide open for minimum thrust * b. The nozzle goes to minimum operating at er.. c. The nozzle changes to cause a... d. --- e. Nozzle open wide when min thrust f.Nozzle close to minimum g. Can provide free path for sonic airflow by keeping the nozzle wide open, the engine idle speed can be held high with a minimum of thrust produced 165. Variable area exhaust nozzle a. Wide open at minimum thrust * b. Minimum RPM at idle c. Nozzle changes area to cause supersonic flow condition 166. Moveable tail moves towards the turbine outlet, it will change? a. Nozzle area b. Exhaust velocity * c. Choked limit -if the plug moves towards the turbine outlet, its effect is to reduce the area and as a result the exhaust velocity is also changed 167. In order to regain lost performance of the engine, can use converging: Higher exhaust speed: …regain performance, it can be controlled by: a. Exhaust cone b. Exhaust strut c. Tailpipe * 168. Exhaust cone shape: a. Convergent, conical, and cylindrical * Thrust Reverser 169. On a turboprop engine, reverse thrust action: a. Reversing the exhaust flow by clamshell door b. Changing the pitch of the propeller blade * c. Feathering the propeller 170. The thrust reverser clamshell door is used to a. Prevent air leakage into the engine exhaust * b. Decrease the exhaust area so as to increase the engine thrust c. Spoil the hot stream exhaust so as to decrease engine thrust One method uses clamshell-type deflector doors to reverse the exhaust gas stream, -clamshell door: redirects the fan air to produce forward thrust The clamshell doors are operated by pneumatic rams through levers that give the maximum load to the doors in the forward thrust position; this ensures effective sealing at the door edges, so preventing gas leakage -spoiling the hot stream only decreases forward thrust, but a thrust reverser is used to produce thrust in the other direction (ie. reverse thrust) 171. A aerodynamic type of thrust reverser. Reverse the gas flow of the exhaust gases from: The vane of the blocker door type thrust reverser is installed at: a. Pre-exit position * b. Post-exit position c. Either a pre-exit or post exit position In the aerodynamic-blockage type of thrust reverser, thin airfoils or obstructions are placed in the gas stream, either along the length of the exhaust duct or immediately aft of the exhaust nozzle -see RR pg 173 172. T/R blocker door type consist of: a. Hydraulic motor, XXX, Gear box b. Air motor, flexible shaft, screwjack * c. Hydraulic actuator, gearbox, screwjack The cold stream reverser/hot stream spoiler system is actuated by an air motor, the output of which is converted to mechanical movement through a series of flexible drives, gearboxes and screwjacks. For larger engines, hydraulic actuators are employed to drive the translating cowl and blocker doors. 173. Thrust reverser using pneumatic actuator, operating pressure is ensured by: a. Isolating valve b. Pressure regulating valve * c. Directional valve 174. A mixed exhaust nozzle on a turbofan engine would have in its configuration: a. One thrust reverser, normally as part of the exhaust * b. Both cold and hot stream thrust reversers c. A turbofan thrust reverser only Mixed exhaust turbofans are configured with one reverser, while unmixed or bypass exhaust turbo fans often have both cold stream and hot stream reversers. Some high bypass turbofans will have only cold stream reversing because most of the thrust is present in the fan discharge -(b) is wrong, but what is the difference between (a) and (c)? 175. High by-pass turbine engine. Why only the cold stream have T/R? a. No space for T/R at hot stream b. No material can stand for the hot temp c. The majority of thrust comes from cold stream* 176. Thrust reverser deployed, the EPR: a. Less than 1 b. Negative c. No use condition / Inoperative in that moment * 177. When deploying thrust reverser to open: a. Engine running at idle b. Throttle lever at idle position A reverse thrust lever in the crew compartment is used to select reverse thrust; the lever cannot be moved to the reverse thrust position unless the engine is running at a low power setting Afterburner 178. Afterburner components a. Burner, jet pipe, thrust reverser b. Burner, jet pipe, variable area propelling nozzle * c. Burner, tail pipe, variable area propelling nozzle -see RR pg 183 179. Afterburner increase mass flow rate and also increase a. Temperature * b. Compressor RPM c. Compressor compression ratio 180. The effect of afterburning: a. Increase 50% of thrust and 100% of fuel flow b. Increase 100% of thrust and 100% of fuel flow c. Increase 50% of thrust and 150% of fuel flow * -pg 503 181. Construction of afterburner: a. Needs exclusive material * b. Prolong of tail pipe The afterburning jet pipe is made from a heat resistant steel alloy and requires more insulation than the normal jet pipe – pg 510 182. The afterburner jet pipe a. Require a two position (convergent and divergent duct) b. In an extension... c. Uses extrusively... * The propelling nozzle is of similar material and construction as the jet pipe, to which it is secured as a separate assembly. All engines which incorporate an afterburner must, of necessity, also be equipped with either a two-position or a variable-area exhaust nozzle in order to provide for proper operation under afterburning and nonafterburning conditions. – pg 510 Efficiency 183. The requirements for an efficient compressor is a. High RPM, high pressure ratio, high temperature rise b. Low RPM, low-pressure ratio, high temperature rise c. Low RPM, high-pressure ratio, low temperature rise * -ideally, the compressor will compress the air without changing its temperature (and hence no entropy rise) 184. For any given engine, if the velocity of the jet stream is increased this will cause: a. Overall efficiency to increase b. Propulsive efficiency to decrease * c. Thrust to decrease -ue increase will cause thrust to increase (see momentum thrust), so c is incorrect -see mathematical derivation, propulsive efficiency will decrease if u e increases 185. Overall efficiency is thermal efficiency plus a. Thermodynamic efficiency b. Propulsive efficiency * c. Isometric efficiency -overall efficiency is thermal efficiency multiplied by propulsive efficiency 186. Kinetic energy change to propulsive energy a. Kinetic efficiency b. Propulsive efficiency * c. Thermal efficiency 187. The efficiency of converting fuel energy to kinetic energy is: Fuel burn to propulsion a. Adiabatic efficiency b. Propulsive efficiency c. Thermal efficiency * -factors that affect thermal efficiency: turbine inlet temperature, compression ratio of compressor, turbine/compressor efficiency Fire Extinguisher 188. MB extinguisher neck at: a. Bottom. * b. Top. c. Middle. 189. Fire extinguisher a. Halogen Nitrogen b. CO2** c. CTC d. --- e. Pump +TCT f.Sphere cylinder + N2 halon* g. CO2 Halons have, until recently, been in almost universal use in aircraft fire extinguishers, both portable and fixed. Halon 1211 is used only in portable extinguishers and is a streaming agent Halon 1301 is used only in fixed extinguisher installations typically cargo holds or engines and is a total flooding agent. http://www.skybrary.aero/index.php/Halon_Fire_Extinguishers BCF or Halon extinguishers is the best answer 190. Engine fire bottle a. Special and filled with halon * b. Contain compressed CO2 c. Have high volume pump 191. Fire bottle cartridge check with a. Safety (low current) ohmmeter * b. 250 volt megger c. H.T. voltmeter Never check the continuity of the cartridge using a conventional ohmmeter. – pg 709 -but nowadays replaced by halon 1301 192. The serviceability of a extinguishing bottle can be check by a. Pressure check b. Weight check c. Pressure and weight check * -see page 710 193. Which is a true statement regarding the engine fire extinguisher? a. A container mounted on non-fire zone * b. Discharge to the component 194. The extinguishant to be used for engine fire is: a. The amount to give a concentrated discharge for 30 seconds. b. Released by the action of an electrical solenoid c. In pressurized containers located outside the fire risk zone. * Pressurized containers are provided for the extinguishant and these are located outside the fire risk zone extinguishant is discharged from the containers through a series of perforated spray pipes or nozzles into the fire (fig. 14-4). The discharge must be sufficient to give a predetermined concentration of extinguishant for a period that may vary between 0.5 seconds and 2 seconds. – RR pg 167 195. How to operate fire extinguisher: a. Manually discharge by valve b. Electrically cartilage fire to rupture pin to cylinder head * c. Electrically operate valve to discharge fire extinguish element to engine -discharged by electrically firing cartridge units within the extinguisher discharge heads. – pg 704 196. If a thermal discharge causes the fire bottle disc to rupture, the extinguisher discharge a. Into the nacelle b. Overboard * c. Through the discharge nozzles The thermal discharge indicator is connected to the fire container relief fitting and ejects a red disk to show when container contents have dumped overboard due to excessive heat. - http://okigihan.blogspot.hk/p/engine-fire-extinguishing-system.html 197. When fire bottle is discharged: a. Fire discharge solenoid energized b. Plug unlocks automatically c. Indication to the system that fire bottle discharge has taken place * Fire Detection 198. Fire detector sensor, temperature setting: a. Set during transit check b. Sealed and set by manufacturer, and cannot be changed * c. Set during maintenance Detectors or control units of anyone type may have alternative temperature settings and the part number marked on the case is the only positive means of identification of the warning temperature. – pg 681 199. Fire detection wire loop, why is it installed with rubber plastic clip: a. Resistance insulation of the wire b. Prevent corrosion with the engine support c. Reduce heat exchange and protect the wire from sharp clip * d. --- e. Prevent corrosion f.Less heat loss/transfer g. Absorb vibration* To help absorb some of the vibration produced by the engine, most support clamps use a rubber grommet that is wrapped around the sensing element - [Jeppesen A&P Technician Book Powerplant Page 11-9] 200. A continuous wire type fire detector relies on _______ operation on the temperature dependence of? a. The capacitance or resistance of the detector element * b. The capacitance of the winding in the control relays c. The resistance of the winding in the control relays -pg 684 201. Thermistor type continuous loop system, senses temperature increase by: a. Sense the rise of the temperature b. Sense the decrease of resistance * c. Sense the increase of the resistance The fire sensor element is filled with thermistor- a negative resistance coefficient material. As the temperature of the core increases, electrical resistance to ground decreases. – pg 685 202. Thermistor: a. Positive temperature coefficient b. Negative temperature coefficient * 203. In most pneumatic continuous loop fire detector, a. Use thermo-switch b. Compare local & general heat rises * c. Use ceramic continuous loop… (better) [Jeppesen A&P Technician Book Powerplant Page 7-76 Lindberg / Systron-Donner system] Systron-Dornier Fire Sensor: This type of fire detector is a pneumatic device that is sensitive to fire/overheat temperature -based on gas laws, heat added at constant volume -> pressure increases -Kidde continuous loop fire detector: two wires embedded in ceramic insulator and conductivity increases as it gets hotter The pneumatic detector has two sensing functions. It responds to an overall average temperature threshold and to a localized discrete temperature increase caused by impinging flame or hot gasses. Both the average and discrete temperature are factory set and are not field adjustable 204. Fire discharging circuit…..relay…… a. Mechanically by cable and linkage b. Automatically by electrical circuit c. Circuit completed by power of bus bar * 205. Pull of fire handle implement a. Mechanical and linkage b. Powered electrically by main aircraft battery * c. Discharge automatically when electrical power cut-off Thrust 206. Gross thrust is calculated: a. Net thrust add static thrust b. Mass flow / thrust c. When the aircraft is on the ground Gross thrust is the sum of all forward thrust components: Gross thrust = Momentum thrust + Pressure thrust Net thrust = Gross thrust - Momentum drag (in absolute terms; momentum drag and net thrust are actually opposite direction vectors) Static thrust is just a standard of evaluating engines, when you measure thrust output of the engine on the ground 207. If the gross thrust of an engine was computed at 1000 lb, net thrust of the engine in an aircraft traveling at 500 ft per second will be? a. Less than gross thrust * b. Greater that gross thrust c. Unaffected by speed Gross thrust is only the forward thrust, net thrust is lower because it takes into account the momentum drag 208. Propeller thrust (not sure) is the product of, a. ESHP & airspeed * b. ……. & density c. SHP & propeller efficiency -SHP is the shaft horsepower, which is the amount of useful power generated by the propeller -there is a small amount of hot jet thrust (usually less than 10% of total power), if you want to include that little bit, you can put it in ESHP (equivalent shaft horse power) POWER = THRUST x VELOCITY 209. When air thrust increases: a. Power of the powerplant increases b. Power of the powerplant decreases c. Power of the powerplant remains unchanged * POWER = THRUST x VELOCITY -power does not necessarily change 210. Thermodynamic horsepower is? a. Horse power measured at dynamometer b. Horse power……thermo…..internal The power that would be produced by a turboprop engine under standard sea-level conditions if the engine were run at a maximum turbine inlet temperature. 211. The total equivalent shaft horse power of a propeller turbine engine: a. Is the horse power developed by the turbine b. Is the horse power developed by the turbine less than the power required to drive the compressor c. Is the horse power available to the propeller plus the power available in the jet efflux * As only a small proportion of the exhaust gases end up as useful thrust the power outputs of turbo-propeller engines are expressed in shaft horse power (SHP). To this figure must be added that small amount of exhaust gas that gives thrust, this figure is usually less than 10% of the total power produced by the engine, the total engine power is then expressed as equivalent shaft horse power (ESHP). – pg 520 212. As air temperature increase the net thrust at any given throttle setting a. Decrease * b. Remains constant c. Increase In other words, as outside air temperature (OAT) increases, air density decreases. Anytime the density of the air entering a gas turbine engine decreases, engine thrust also decreases 213. Atmospheric temperature decreases a. Increase fuel to maintain same speed * b. Decrease fuel to maintain same speed c. No change in fuel flow and engine speed On a cold day the density of the air increases so that the mass of air entering the compressor for a given engine speed is greater, hence the thrust or s.h.p, is higher. The denser air does, however, increase the power required to drive the compressor or compressors; thus the engine will require more fuel to maintain the same engine speed or will run at a reduced engine speed if no increase in fuel is available. – RR pg 231 214. Altitude increase causes: a. Thrust decrease * b. Temperature decrease c. Function of density Altitude increase -> density decrease -> mass flow rate decreases -> thrust decrease 215. The relationship between altitude and thrust, a. Higher the altitude, lower the thrust * b. Directly function of density c. Related to ambient temperature 216. An increase in altitude at fixed throttle setting: a. Would cause an increase in engine pressure ratio (EPR) b. Would cause a decrease EPR * c. Would have no effect in EPR 217. Under the same thrust setting, altitude increase: a. EGT increase, thrust decrease b. EGT increase, thrust increase c. EGT decrease, thrust decrease * 218. When the engine climbs in constant throttle, the engine EPR will: a. Remain constant b. Increase c. Decrease * 219. When EPR is not changed with different altitude, the net thrust force: a. Increases with altitude b. Decreases with altitude c. The fuel metering unit compensates it * -EPR is a measure of thrust; if EPR is not changed, then the net thrust stays the same 220. The relative air flow is getting faster, and the net jet thrust would a. Increase * -for jet thrust, the aircraft is flying fast enough such that the ram effect would dominate increase in airspeed 221. Velocity of jet stream increase a. Thrust increase * 222. Airspeed increase: a. SHP increase, jet thrust decrease b. SHP decrease, jet thrust increase* c. SHP and jet thrust remain constant 223. High humidity, power will a. Increase b. Decrease c. No significant change 224. Gas turbine engine take-off with humid weather: a. Loss of thrust b. c. No noticeable effect compare to piston engine counterpart * 225. Use of part power setting during trim runs will: a. Reduce hot section life b. Increase hot section life * c. Increase noise levels but reduce fuel consumption 226. Use engine on idle speed…….. a. Longer hot section life * b. Shorter hot section life 227. Engine trimming of the part power setting is used for: a. Increase noise b. Decrease service life a. Increase service life and increase noise * The RPM which gives the specified rated thrust output under standard-day sea-level static operation is known as "engine trim speed"…. The process of adjusting the fuel control is called "engine trimming". …most commercial engines are trimmed at "part-power" or part-throttle for field adjustment to compensate for deterioration with age or change in control components. -HAECO notes Ch 1-4 pg 144 Water Injection System Adding water increases the mass being accelerated out of the engine, increasing thrust, but it also serves to cool the turbines. Since temperature is normally the limiting factor in turbine engine performance at low altitudes, the cooling effect allows the engine to be run at higher RPM with more fuel injected and more thrust created without overheating. The drawback of the system is that injecting water quenches the flame in the combustion chambers somewhat, as there is no way to cool the engine parts without coincidentally cooling the flame. This leads to unburned fuel out the exhaust and a characteristic trail of black smoke. 228. Take-off wet thrust / SHP engine power rating ???? maximum power available ? a. For emergency situation and is not time limited. b. While using water injection and is normally limited operation time * c. At standard condition and engine are trimmed to this rating Takeoff (wet) - This is the maximum thrust certified for takeoff for engines that use water injection. The rating is selected by actuating the water injection system and setting the aircraft throttle to obtain the computed 'Wet’ takeoff Thrust in terms of engine pressure ratio. The rating is restricted to takeoff, is time limited, and has altitude and ambient air or water temperature limitations. 229. Wet thrust a. Used in high temperature with limited time * b. Used in high altitude c. No limit 230. Water injection is used a. Normally under landing b. Under bad weather condition c. Under high ambient temperature takeoff * 231. High ambient temperature will a. Sometimes add water in the inlet to reduce the temperature * b. c. Turbo engine affect less than piston engine 232. The use of water injection in a gas turbine engine is for the recovery of thrust when the engine is operating at: a. Low density altitudes b. High altitude cruise c. Take-off power * 233. Where to use water injection? a. Compressor inlet or combustion chamber * b. Compressor inlet or turbine c. Combustion chamber or turbine 234. Gas turbine water injection system are designed to spray water into the: a. Compressor outer and /or the combustion chamber outlet b. Compressor inlet and/ or the combustion chamber inlet * c. Free turbine Water may be injected directly into the compressor inlet, the diffuser just ahead of the combustion chamber, or both the inlet and diffuser. – Jeppesen Ch 7 pg 17 235. Water used in water injection system is a. Demineralised water * b. Tap water c. Methanol *Demineralized water & water/methanol.? 236. Water/methanol in water injection is a. Power increase with no fuel flow increase b. Power increase by burning methanol, no fuel flow increase * c. Power increase by burning methanol, fuel flow increase Furthermore, the lower turbine inlet temperature resulting from water injection allows the fuel control to increase the fuel flow to the engine. -fuel flow may increase, but not necessarily out 237. Primary purpose of methanol in water injection a. To reduce turbine inlet temperature b. Lower freezing point of water c. To add power as fuel * A typical water injection system uses a mixture of water and methanol. This is done because injecting only water reduces the turbine inlet temperature. The addition of methanol partially restores the drop in turbine inlet temperatures because the methanol acts as a source of fuel and burns in the combustion chamber. In addition, the methanol works as an antifreeze to help prevent the water from freezing when the aircraft climbs to altitude. -methanol is used both for anti-icing properties and as a fuel 238. Water injection a. Water cooling, alcohol for anti-freeze * b. Alcohol cooling, water increase air density c. Alcohol cooling, water enrich oxygen [RR Page 181] 239. An injection of water methanol... a. Cooling the air mass, * b. Supplement the fuel.. c. Increasing the velocity.. 240. Once the water injection system is activated, what to do with the remained water? a. Leave it as it is, will be kept for further use b. Will be drained overboard * c. All water will be consumed, inject until no more is left over Drains and check valves allow the water supply lines to empty when the system is not in use, preventing freeze-ups. – Jeppesen Ch 7 pg 18 Fuel 241. Fuel is suitable as a lubricant in fuel pump and fuel control unit because it has: a. High viscosity * b. Low viscosity c. Anti-foaming characteristic As a general rule, turbine fuels are much more viscous than reciprocating fuels. This allows the fuel to act as a lubricant in pumps and fuel control units – Jeppesen Ch 7 pg 13 -both high viscosity and anti-foaming characteristic are important characteristics of a lubricant 242. Chose a quality which is NOT practicable for a turbine engine fuel? a. Have as high a calorific valve as possible * b. Do not freeze under all conditions of flight c. Provide adequate lubrication for the moving parts of the fuel system. -the other two are possible to achieve, but calorific value of the fuel can always be higher 243. The turbine fuel designation Jet A1 indicates: a. The freezing point * b. The performance characteristic c. The octane number One thing to keep in mind is that jet fuel designations, unlike those for avgas, are merely numbers that label a particular fuel and do not describe any performance characteristics. – Jeppesen ch 7 pg 12 244. What is Jet A1 fuel? a. Freezing point -47 deg C * 245. Difference between general aviation fuel and Jet A1 is that Jet A1 contains: a. Lead b. Kerosene * The primary difference between aviation gasolines and turbine fuel is that all turbine fuels contain kerosene. Jet A and Jet A1 both contain kerosene, and the ‘A’s are referred to kerosene-type fuel Jet B contains naphtha 246. Turbine fuel and kerosene difference a. In color b. Lead* c. Kerosene The primary difference between aviation gasolines and turbine fuel is that all turbine fuels contain kerosene. Jet fuel is a clear to straw-colored fuel, based on either an unleaded kerosene (Jet A-1), or a naphtha-kerosene blend (Jet B). It is similar todiesel fuel, and can be used in either compression ignition engines or turbine engines. – wiki -impure kerosene will contain lead, but it is a bad quality for turbine fuels because it causes knocking 247. Jet A1 a. Blend of gasoline and kerosene b. Kerosene/Te… lead c. Kerosene * 248. Difference between Jet A and Jet A1 a. ? b. Jet A1 has a lower freezing point than Jet A * c. Jet A has a lower freezing point than Jet A1 249. Extreme low temperature: a. Jet A1 b. Jet A c. Jet B * -jet A: -40 deg C -jet A1: -47 deg C -jet B: -60 deg C 250. Kerosene is more difficult in visual inspection on the contamination of water than gasoline because: a. Kerosene’s SG is far from water b. Kerosene’s SG is close to water * 251. SFC definition: a. (Mention about maximum operating flight, wrong) b. One unit of fuel used for one unit of thrust provided * c. How much fuel use in one minutes to produce maximum power (Thrust) specific fuel consumption: how much fuel required to produce one pound of thrust 252. To achieve at low SFC a. Higher thrust setting b. Higher exhaust velocity * c. Low temperature gas If a high thrust level is to be obtained, a tremendous amount of fuel has to be burnt. This will result in high fuel consumption – pg 27 -> (a) is not correct Higher exhaust velocity (assuming that there is no fuel penalty) will create more thrust, and so you don’t burn as much fuel The final term, best economy, describes the mixture ratio that will develop the greatest amount of engine power for the least amount of fuel flow. This condition is usually obtained by leaning the mixture control until the highest exhaust gas temperature and rpm are achieved while throttle is in a set position. Fuel Tank / Refuelling 253. Location of fuel heater a. Between FCU and fuel cock b. Between HP pump and FCU c. At upstream of the filter * -fuel cock = fuel valve In sequence: boost stage (up to LP), fuel heater, filter, gear pump (up to HP), fuel metering unit (FMU) On many engines, a fuel-cooled oil cooler (Part 8) is located between the L.P. fuel pump and the inlet to the fuel filter (fig. 10-13) – RR pg 126 254. High pressure fuel filter is located: a. Upstream of fuel heater b. Downstream of fuel heater * c. Upstream of booster pump 255. The HP fuel cock is placed in a. Pride engine fuel b. At FCU outlet *** c. After the fuel/air cooler 256. Fungi and bacteria presence in the fuel tank a. Corrosion * b. Water contamination c. Fuel-Ice Water can hasten fungal growth, causing corrosion in fuel tanks. Microbiological contamination of fuel can cause inaccurate fuel contents indications, blockage of filters, and corrosion of aluminium alloy fuel tanks. 257. Where fungi and bacteria accumulate at the bottom of the fuel tank? When fungal and bacteria in fuel tank,... a. Corrosion will take place and sometime to an appreciable extent. * b. Wet wings will not be affected c. Fuel ice contamination will result * 258. Low pressure backing fuel pump? a. Supply a sufficient fuel pressure for HP pump * b. Use while HP fuel pump failure c. Transfer fuel from pipe to another To ensure that a satisfactory fuel pressure to the spray nozzles is maintained at high altitudes, a back pressure valve, located downstream of the throttle valve, raises the pressure levels sufficiently to ensure satisfactory operation of the fuel pump servo system. – RR pg 113 259. The purpose of the fuel drain system on a gas turbine engine is to: a. Drain the unburned fuel collected in the combustion chamber whilst the engine is running b. Collect the unburned fuel on failure to start and fuel which has leaked from certain fuel system glands. * c. Return fuel to the inlet side of the fuel control unit when the pressure cock is closed A fuel drainage system accomplishes the important task of draining the unburned fuel after engine shutdown. Draining accumulated fuel reduces the possibility of exceeding tailpipe or turbine inlet temperature limits due to an engine fire after shutdown. In addition, draining the unburned fuel helps to prevent gum deposits in the fuel manifold, nozzles, and combustion chambers which are caused by fuel residue. Oil Oil system pressure relief valve: opens when oil pressure is too high, and also open for cold start Main oil filer pressure relief valve: bypasses filter if filter is blocked Fuel/oil cooler bypass valve: bypasses the heat exchange mechanism if FUEL temperature is too high; there is also a trim flow route for excess oil from the cooler, because pump capacity is more than you actually need 260. What is the function of the oil system relieve valve? a. Regulate oil pressure * b. Minimize oil loss c. Provide a filter bypass 261. Oil pump relieve valve is to a. Protect the oil cooler b. Regulate oil pressure c. Provide a recirculating loop in case of system blocked * PUMP relief valve: This valve is set to open at a much higher pressure than the system relief valve and opens only to return the oil to the inlet side of the pump should the system becomes blocked 262. What is the function of oil bypass valve? a. Pass unfiltered oil when filter blocked * b. Regulate the pressure 263. When will oil cooler valve bypass be open: a. Oil cooled, and is the valve is blocked * b. Oil cooler is blocked, and oil pressure is high c. Oil cooled,... d. --- e. Oil cool & cooler blocked* f.Oil cool & oil pressure too high g. Oil pressure too high & cooler blocked When the oil is cold, the bypass valve allows the oil to bypass the cooler. However, once the oil heats up, the bypass valve forces the oil to flow through the cooler. -EEC allows oil to bypass the fuel/oil cooler under certain fuel temperature and fuel flow conditions -if oil pressure is too high, there is a different trim valve from the fuel/oil cooler back to the tank but it doesn’t bypass the actual cooler 264. Oil filter, bypass relieving valve a. Prevent the oil back flow to the oil pump b. Let unfilled oil through the pump when the boost pump is shut off * 265. In oil lubrication system, last chance filter is located at a. Scavenge line b. Outlet of oil tank c. Oil line before oil jet spray* 266. Magnetic chip detector (MCD) located at a. Pressure pump outlet b. Scavenge line * c. Filter outlet Chip detector’s and magnetic plugs are often fitted in the oil system in the return oil side, and should be removed for examination at regular intervals for presence of metal particles. 267. Magnetic plug is installed a. Into the flow b. In order to pick up the ferrous chips * c. ? return line 268. Magnetic plug usually install with a. Oil-drain plug * b. Oil-fill plug -usually referred to as magnetic drain plug 269. Magnetic detector is a. Fitted at case drain for collect ferrous debris b. Inserted in oil line for conditioning & monitoring * [Jeppesen A&P Technician Book Powerplant Page 9-33] Magnetic plugs or chip detectors may be fitted in the return oil side of a system to provide a warning of impending failure without having to remove and inspect the scavenge strainers. -magnetic detector is more for monitoring that for actually picking up garbage from the oil line 270. Magnetic(?) plugs are? a. Fitted on the case-drain lines to collect ferritic debris b. Inserted in the oil flow and inspected for condition and monitoring * c. Installed one for each pump and retained within a selfsealing valve housing. 271. Dry sump lubrication system a. Oil is carried in its own separated oil tank* 272. Dry sump system of engine, the oil tank: a. Does not need expandable space b. May have expandable space filled extended range and transit c. Must need expandable space * 273. Compressor oil leakage caused by a. Seal failure * 274. An oil leak into compressor may cause a. Increases in oil and breather pressure b. Burning and distress on the compressor c. Oil baking onto the compressor or dirt sticking to it. * The primary source of oil contamination in a reciprocating engine is combustion byproducts that escape past the piston rings and oil carbonizing that occurs when oil becomes trapped in the pores of the cylinder walls and is burned. Additional contaminants that can become trapped in lubricating oils include gasoline, moisture, acids, dirt, carbon, and metal particles. If allowed to accumulate over a period of time, these contaminants can cause excessive wear on internal engine components. 275. Internal oil leaking of... may: a. A decrease in fuel consumption b. A decrease in engine performance * c. A decrease in breather pressure 276. Oil tank a. Always pressurized b. Has a vent * -in accordance with FAA regulations: http://www.flightsimaviation.com/data/FARS/part_23-1013.html 277. Sub vent pressure system in oil tank, function a. Slightly negative to assist the flow b. To ambient pressure to prevent pump cavitation c. Slightly positive to prevent pump cavitation * To ensure a positive flow of oil to the oil pump inlet, most oil reservoirs are pressurized. Pressurizing the reservoir also helps to suppress oil foaming which, in turn, prevents pump cavitation. 278. Oil pressure pump: a. b. Gear pump & helical c. Piston & gear pump * The two types of constant displacement pumps that are used in reciprocating engine lubrication systems include the gear and gerotor pump. 279. Measuring the engine oil temperature at? a. Within oil tank * b. Measuring at the point where oil flow into bearing compartment c. Measuring at the point where oil flow out bearing compartment The oil temperature indicated is sensed either in the oil tank or plumbing to the pressure pump or in the oil pressure supply line from the pump. 280. Engine oil flow plan a. b. Cooler first then to the veering gears  hot tank c. To the bearing gears, then scavenge to the drain system, back in cooler  cold tank 281. The difference between a hot tank and a cold tank is that hot tank is: a. Inside the engine b. Located downstream of sub-pressure system * c. Located upstream of sub-pressure system* 282. Hot tank lubrication system, the oil from boost pump direct to: a. Cooler -> bearing and gear * b. System breather -> fuel-oil-cooler -> bearing and gear c. Bearing and gear -> from scavenge to cooler 283. Cleanable oil filter components: a. Screen, spacer, and water * b. Pleated screen, pleated spacer, and pleated water c. Screen, spacer, and consumable screen d. --- e. Screen and spacer, pleated screen and water screen f.Pleated screen, pleated space, and water screen * g. Water screen, screen and spacer and disposable screen A typical screen-disk filter consists of several wafer-thin screens that are separated by spacers. This configuration allows the filter to be easily disassembled and cleaned. Lubrication systems (chp 9) pg 30 – pleated filter is separate from cleanable filter 284. Which statement is correct? a. Synthetic turbine oils will affect thermosetting plastics. b. Prolonged exposure to synthetic oils may cause dermatitis * c. The flush points of synthetic turbine oils are very low [Jeppesen A&P Technician Book Powerplant Page 9-6: Can soften rubber products & resin] 285. Engine lubricating oil is a. Synthetic oil * b. Mineral oil c. Heavy duty oil Mineral oil: reciprocating engine Synthetic oil: turbine engine 286. Engine oil is best to use: a. Low viscosity b. High viscosity * c. Constant viscosity Gas turbine engine oil must have a high enough viscosity for good load carrying ability, but it must also be of sufficient low viscosity to provide good flow ability Oils used in reciprocating engines usually have a relatively high viscosity for several reasons. 287. Synthetic lubrication oil spillage, what to do: a. Wiped, washed, and cleaned with suitable cleaning agent * b. Neutralized with an approved agent c. Mopped up and flushed with plenty of water If a spill occurs, wipe it up immediately with a petroleum solvent. Engine Control (FADEC / EEC) 288. For FADEC powered engine, an alternate mode operation means: a. For ground test purposes b. If the prime power parameter fail * c. For use on take-off only The computer that controls your engines like to do it using EPR but if something prevents that, it can also use LP RPM. - http://code7700.com/g450_fadec_alternate_control_mode.html 289. FADEC power from: a. Aircraft electrical battery b. Engine special generator * c. ? engine shut down, and when engine running -the engine has its own PMA to generate AC, just for the EEC 290. EEC conjunction is used with: a. Pressure injection system b. Hydro-mechanical unit c. FADEC * FADEC = EEC + powerplant subsystems/components + aircraft interfaces A supervisory EEC consists of an electronic control and a conventional hydromechanical fuel control unit A full-authority digital engine control, or FADEC, performs virtually all the functions necessary to support engine operation during all phases of flight. In addition, all FADEC systems are fully redundant and, therefore, eliminate the need for a hydromechanical fuel control unit. A typical FADEC system consists of a redundant, two-channel EEC that can pull information from either channel. 291. The main advantage of FADEC is: a. Efficiency is always maximum, reduce complexity, add flexibility * 292. When an engine is overspeed, FCU will: a. Cut off the fuel supply b. Reduce the fuel flow to reduce the speed * 293. The HP shaft is overspeed: a. b. Reduce the fuel flow rate * c. Immediately cut the fuel flow -most automatic fuel control units sense inlet air temperature, compressor RPM, burner pressure, position of power lever 294. In turboprop, turbine N2 indication too high, engine will a. Bleed off compressor air b. Decrease fuel flow * 295. The difference of FCU in turbojet and turboshaft engine is that FCU in a turboshaft engine also controls: Hydro-mechanical fuel control in turbojet vs turboshaft, FCU in turboshaft also controls: a. N1 and N2 RPM b. Turbine inlet temperature c. Free turbine RPM * 296. Turboshaft engine FCU control: a. Turbine inlet temperature b. Compressor RPM * c. Turbine RPM To do this, the fuel control unit monitors compressor inlet temperature and engine speed. H.P. compressor shaft r.p.m. is governed by a hydro-mechanical governor which uses hydraulic pressure proportional to engine speed as its controlling parameter. A rotating spill valve senses the engine speed and the controlling pressure is used to limit the pump stroke and so prevent overspeeding of the H.P. shaft rotating assembly. 297. Throttle lever angle is related to a. The throttle lever in the cockpit * b. The EEC transducer / controlled by ECU c. The fuel control system……….. 298. Electrical engine control governor a. TIT, shaft speed, inlet air pressure b. TIT, fuel pressure, inlet air pressure, lever angle * c. Fuel pressure, lever angle As stated in para. 8, some engines utilize a system of electronic control to monitor engine performance and make necessary control inputs to maintain certain engine parameters within predetermined limits. The main areas of control are engine shaft speeds and exhaust gas temperature (E.G.T.) which are continuously monitored during engine operation - 299. Digital Engine Control sensing element a. Fuel Pressure, … 300. Fuel flow regulation principle a. By fuel schedule b. Constant pressure by pressure relief valve c. Differential pressure from throttle position and engine RPM * 301. The fuel control usually senses compre... temperature a. As a function of the density of the... * b. As a base for standard day temperature c. To re reference the EGT limit 302. Gas turbine engine power control by a. Fuel * b. Fuel & intake air c. Intake air -you can’t control intake air; you can only control bleed air 303. When propeller RPM exceed (100% operating RPM)....moves the blade to a a. Lower pitch angle b. Higher pitch angle * c. Free wheeling position 304. Turbo-prop … fuel control … flyweight … is controlled by: a. RPM b. Fuel pressure c. Power spring … * 305. Hyper…. Fuel control, flyweight a. RPM * b. Fuel pressure c. Fuel flow 306. Hydro-mechanical fuel control system governor control by a. Fuel pressure b. Spring feeder The engine speed governor can be of the pressure control type described in para. 15, or a hydro-mechanical governor as described in para. 23. H.P. compressor shaft r.p.m. is governed by a hydro-mechanical governor which uses hydraulic pressure proportional to engine speed as its controlling parameter. A rotating spill valve senses the engine speed and the controlling pressure is used to limit the pump stroke and so prevent overspeeding of the H.P. shaft rotating assembly. The controlling pressure is unaffected by changes in fuel specific gravity. 307. Turboprop overspeed governor is adjusted? a. Automatically during flight * b. In flight by cockpit controls c. When installed [Jeppesen A&P Technician Book Powerplant Page 12-42] 308. When aircraft is flying at high altitude, the fuel control unit: a. Increase the fuel rate when the increase amount of air intake b. Reduce the fuel flow rate * The fuel control unit adjusts fuel flow to match the amount of air intake, because combustion needs to occur at a specific fuel:air ratio If altitude decreases, amount of air decreases, so fuel flow should also decrease Fuel control units meter the correct amount of fuel into the combustion section to obtain an optimum air-to-fuel mixture ratio of 15:1 by weight For instance, as the aircraft altitude increases, the compressor delivery pressure falls and the capsule assembly expands to reduce the V.M.O. 309. Gas turbine engine is controlled at CSD an increase of flight altitude , the sense of fuel ???? such that? Fuel flow when increasing altitude with constant engine speed a. Fuel flow is adjusted to match the increased airflow b. Fuel flow reduces c. Fuel flow remains the same if the forward speed of the aircraft changes by proportional amount. * 310. Altitude increase, and the thrust setting is same, a. Fuel consumption increase b. Fuel consumption decrease * c. No change 311. Airspeed increase with attitude, fuel control unit: a. Adjust the fuel flow, according to the airspeed * b. Reduce the fuel flow Conversely, an increase in aircraft forward speed causes the capsule assembly to be compressed and increase the V.M.O. The reduced system pressure drop causes the fuel pump to increase its output to match the increased airflow. Constant Speed Drive (CSD) 312. CSD warning indicator light are usually operated by: a. Over temperature or over pressure condition b. Over temperature or low pressure condition * c. Over temperature or drive disconnect condition Flight Conditions 313. The highest velocity inside a jet engine is a. At compressor outlet b. At the turbine exit c. At the exhaust * d. --- e. Compressor outlet f.Combustion chamber outlet g. Nozzle guide vane outlet* 314. What does exhaust gas velocity relate to? The velocity of.. through...exhaust... relates to the: The velocity of airflow at propelling nozzle due to a. Potential energy (PE) of gas b. Pressure energy of gas c. Kinetic energy (KE) of gas * 315. In practice, the highest pressure inside a jet engine occurs a. At the compressor outlet * b. At the combustion chamber outlet c. At the turbine EGT, EPR EGT is affected by mixture. Peak EGT occurs at approximately the "stoichiometric" (chemically correct) mixture of 14.7 pounds of air for each pound of fuel, at which there is exactly the right amount of oxygen to oxidize all the hydrocarbon chains in the fuel. Leaner mixtures cause EGT to decrease simply because less fuel produces less energy. Richer mixtures also cause EGT to decrease because excess (unoxidized) fuel absorbs heat energy when it vaporizes. Consequently, peak EGT can be used to identify a stoichiometric mixture, and decreases in EGT from peak can be used to establish mixtures richer or leaner than stoichiometric -this means that bleed valve open (less air to combustor) or bleed valve close (more air to combustor) could both lead to a decrease in EGT depending on what the combustion condition is 316. What is EPR? a. Inlet total pressure to exhaust total pressure ratio * EPR = measured as the ratio of the total pressure in the engine nozzle (after the turbine) divided by the total pressure in the inlet section of the engine (ahead of the compressor) 317. EPR definition a. Inlet to Exhaust b. Exhaust to Inlet * c. --- d. Compressor inlet/jet pipe * e. Compressor outlet/jet pipe f.Compressor inlet/compressor outlet 318. When the engine is stationary, the reading of EPR is a. 0 b. 1 * c. 1.5 -there is no difference in pressure in front of and behind the engine 319. If an engine pressure ratio indicates just above 1 when turbine engine stop running: Engine pressure ratio indicator shows indication just above “1” after engine shut down, a. No action is needed as it is normal * b. It means the transmitter has reading shift and needs replacement c. The indicator is out tolerance and should be adjusted to 1 * d. Not a fault, this is due to drag of measuring equipment and needs calibration ** 320. Blade surge off take ASAP a. Reduce power loss b. Regain pressure and temp compromising engine performance* 321. When the engine surge bleed valve closes, you would observe a. A rise in EPR, a drop in EGT * b. A drop in EPR, a drop in EGT c. A drop in EPR, a rise in EGT d. --- e. A rise in rotational speed and a drop in exhaust gas temperature * f.A drop in rotational speed and a drop in exhaust gas temperature g. A drop in rotational speed and a rise in exhaust gas temperature Bleed valve closure can be confirmed by noting rpm increased approximately 3% and EGT decreased by 50 degrees C from previous IDLE indication Bleed valve CLOSE -> RPM INCREASE + EGT DECREASE -pretty sure that closing the bleed valve will allow more air in the back, which means higher pressure at the back -> higher pressure ratio IF SURGE BLEED VALVE IS OPEN: (For whatever reason, whether is it stuck open or bleed air taken for anti-icing or other) Also, assuming that throttle is left in the same position EPR decreases because there is less air to produce thrust RPM decreases -EGT rises slightly, EPR and RPM shift indications because of change in compression delivered to combustor 322. If the air is supplied from the HP stage compressor for the engine anti-icing: a. EGT and RPM increase b. EGT increase and RPM decrease * c. No change Bleed air anti-icing: A disadvantage of this type of system is that, whenever bleed air is taken from a turbine engine, engine power output decreases. The power decrease is generally indicated by a slight rise in EGT and a shift in both EPR and fuel flow 323. If air is tapped from the high compressor of a turbine engine... a. Engine pressure ratio (EPR) and exhaust gas temperature decreases b. EPR remains constant and EGT decreases c. EPR decreases and EGT increases * 324. When air is taken from the compressor of an airplane engine, its power a. Goes up b. Goes down * c. Remain the same 325. Air bleed from compressor, power and EGT a. Increase, Decrease b. Decrease, Increase * c. (Can’t remember) 326. When there is a leakage of air in the compressor: a. EGT and EPR will decrease -EPR will definitely decrease Seals 327. Turbine interstage seal for the cavities is …. a. Control air cooling & velocity b. Prevent hot gas ingestion by turbine through cavities * Cooling air for the turbine discs enters the annular spaces between the discs and flows outwards over the disc faces. Flow is controlled by interstage seals and, on completion of the cooling function, the air is expelled into the main gas stream Prevention of hot gas ingestion is achieved by continuously sup

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