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Engine · 277 questions

Gas Turbines - USCG Exam Questions

Gas turbine theory, construction, operation, and the support systems found in gas turbine propulsion plants.

Every question below is a real U.S. Coast Guard exam question with four choices. Answer one and the correct choice is revealed instantly, with the USCG reference and illustration where the question uses one.

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Questions 1–100 of 277 · page 1 of 3

  1. #102 When working with gas turbine synthetic lube oil, which of the following safety measures should always be observed?
  2. #124 On the gas turbine shown in the illustration, which of the following best describes the main principle of operation of the component contained within... illustration
  3. #125 The term used to describe a gas turbine in which air drawn from the atmosphere passes through the engine only once is which of the following?
  4. #126 A gas turbine that has a regenerator between the compression and combustion sections in which exhaust gas heat energy is added to the air charge is cl...
  5. #127 The term used to describe a gas turbine in which the turbine exhaust passes through a cooler and back to the compressor inlet is which of the followin...
  6. #129 In a regenerative or recuperative gas turbine cycle configuration, the heat of the turbine exhaust gas is used to do what?
  7. #131 For the same amount of available power, how does a low speed two-stroke diesel engine compare to a recuperated gas turbine configuration?
  8. #134 Assuming you maintain the same power output, how will a decrease in the compressor inlet air temperature effect a gas turbine engine's efficiency and...
  9. #135 On a gas turbine engine, a high outside air temperature can cause high turbine inlet temperature, low mass/weight of airflow through the turbine, and...
  10. #136 Assuming that the turbine inlet temperature of a gas turbine engine remains constant, which of the following operating parameter changes would be note...
  11. #138 What design feature is incorporated into the main propulsion gas turbine to eliminate compressor surge?
  12. #139 What is the designed compressor pressure ratio of the gas turbine compressor rotor shown in the illustration? Illustration GT-0004 illustration
  13. #142 Which of the following components are installed in the lube oil system shown in the illustration? Illustration GT-0024 illustration
  14. #143 How many lube oil sumps are installed on the marine gas turbine engine shown in the illustration? Illustration GT-0024 illustration
  15. #144 Which of the following is true concerning the main engine lube oil system of the marine gas turbine shown in the illustration? Illustration GT-0024 illustration
  16. #148 Lubricating oil contamination in a gas turbine bearing oil sump will most likely come from which of the following?
  17. #152 The Main Fuel Control module used on a marine gas turbine engine as shown in the illustration, is responsible for managing which function(s)? Illustra... illustration
  18. #154 A fuel analysis report for a gas turbine propelled vessel indicates a calcium level in excess of 0.5 ppm. High calcium levels in distillate fuels for...
  19. #155 A gas turbine engine is experiencing a high rate of corrosion in the hot section of the engine. Which of the following fuel contamination issues could...
  20. #156 During an operation of a gas turbine equipped with an intercooler and recuperator, a low combustion air temperature to the combustor section could be...
  21. #160 On a gas turbine powered vessel equipped with a synchro self shifting (SSS) clutch, you are preparing for a power turbine over speed test. What would...
  22. #161 What type of main reduction gear arrangement prevents independent axial and rotational movement of the pinions?
  23. #163 The main thrust bearing directly positions which part(s) of the main reduction gear?
  24. #165 Gear backlash is best described as which of the following?
  25. #170 On a gas turbine powered vessel, what is the last step after an off-line water wash?
  26. #172 On a gas turbine propulsion vessel, you notice a slow but steady increase in gas turbine vibration and specific fuel consumption as the voyage has pro...
  27. #184 When conducting a borescope inspection of the compressor, why can Airfoil and tip cracks be difficult to detect?
  28. #185 When inspecting the combustion section of a gas turbine engine, what wattage light source should you use?
  29. #187 A reddish -colored oxide usually forms on which of the following metals?
  30. #188 A white-gray powdery deposit can usually found on which of the following metals?
  31. #189 Active corrosion on copper alloys is indicated by which of the following?
  32. #191 Compressor tip clang can be usually attributed to which of the following operating conditions?
  33. #192 Compressor rotor blade tip curl is usually caused by which of the following?
  34. #193 Once a compressor is broken in, which of the following factors will most likely cause blade tips to rub?
  35. #197 A compressor blade platform that is tilted or raised may indicate which of the following failures?
  36. #200 The dimples of a combustor dome band that has a low operating time will usually have what kind of damage?
  37. #201 Distortion of the combustor liner assembly is evident when you observe which of the following conditions?
  38. #202 Which of the following is the most probable cause if, while underway, the main propulsion gas turbine air intake blow-in doors open?
  39. #204 In which of the following ways can compressor surge cause excessive temperatures in the turbine section?
  40. #205 On the marine gas turbine engine shown in the illustration, what temperature should be carefully monitored following a shutdown for an engine fire? Il... illustration
  41. #206 On a ship with a marine gas turbine as shown in the illustration, a fire emergency stop is initiated when __________. Illustration GT-0017 illustration
  42. #207 If a fire is detected in a main propulsion gas turbine enclosure, which of the following would occur prior to automatic release of the fire extinguish...
  43. #209 During an operation of a main propulsion gas turbine, the engine shuts down. Which of the following is the most probable reason for the shutdown?
  44. #210 Which of the following is the most likely cause for the main propulsion gas turbine engine tripping during start up?
  45. #214 A total of how many shock mounts are used to secure the LM2500 enclosure to the ship's foundation?
  46. #220 Which of the following components prevent(s) objects smaller than 1/4 inch from entering the engine?
  47. #233 The thermal energy added to the gas as it flows through the combustion section has what effect on the gas?
  48. #234 In a gas turbine, the air charge is permitted to be compressed adiabatically by what factor, process, or condition?
  49. #235 The Brayton Cycle is a series of events best described by which of the following statements?
  50. #236 Why is a gas turbine considered to operate on the Brayton cycle?
  51. #237 In a twin-spool turbine, secondary air is most essential for cooling in what section?
  52. #238 Which of the following statements is true regarding centrifugal compressors?
  53. #239 A centrifugal compressor assembly consists of which of the following?
  54. #240 While air is being compressed in a centrifugal flow gas turbine, what happens to the direction of air flow?
  55. #241 What is the disadvantage of a dual-entry centrifugal compressor compared to a single-entry centrifugal compressor?
  56. #242 When working in or around intake areas, which of the following precautions should be taken?
  57. #243 On the GE LM2500 gas turbine engine, magnetic pickups are utilized for what purpose?
  58. #244 In a gas turbine propulsion installation, the typical control system is designed to perform which of the following three functions?
  59. #245 Thermal energy is the only form of energy that can be added to or removed from a substance. How is thermal energy that is added to a substance stored?
  60. #246 Rankine is the temperature scale that corresponds to which of the following?
  61. #247 Which of the following terms refers to thermal energy in transition?
  62. #248 Kelvin is the absolute temperature scale that corresponds to which of the following?
  63. #249 What is the term given to a process that occurs without a loss or gain of heat?
  64. #250 Which of the following is the definition of absolute temperature?
  65. #251 What is the purpose of the spring in a lip-type oil seal?
  66. #252 What type of air seal is used in the combustor and turbine mid-frame of a gas turbine?
  67. #253 What type of seal is used in the gearbox of a gas turbine engine?
  68. #254 What type of air seal is used in the sump and turbine areas of a gas turbine engine?
  69. #256 Which of the following statements is true concerning the fuel oil ignition system of the gas turbine engine shown in the illustration? Illustration GT... illustration
  70. #264 In comparing a centrifugal-type to an axial-type compressor, which of the following statements is true?
  71. #265 The two basic types of compressors used in gas turbine engines are which of the following?
  72. #266 Rotation of the Controllable Pitch Propeller (CPP) blades is achieved through axial movement of what component in the hub body assembly?
  73. #267 The fuel oil system of a gas turbine engine provides all EXCEPT which of the following?
  74. #268 Gas turbine fuel manifold pressure is established by which of the following actions?
  75. #269 Before combustion can occur, the combustion air must be delivered to the combustor at a high-pressure and low-velocity. High-velocity, low-pressure ai...
  76. #270 In a centrifugal compressor, which component reduces the velocity and increases the static pressure of the air?
  77. #271 Which of the following wrenches should NOT be used while working on a gas turbine?
  78. #272 Which of the following instruments is designed to help you when performing an internal inspection of the gas turbine engine?
  79. #273 The only hand tools that should be used on gas turbine engines are chrome plated, nickel plated, or which of the following?
  80. #274 Wrenches that are recommended for use on gas turbine engines should be plated with which of the following elements?
  81. #277 How is the clutch shown in the attached illustration engaged? Illustration GT-0018 illustration
  82. #278 The term "lockout" on the Synchro-Self-Shifting (SSS) clutch system means that the _________.
  83. #279 How do you manually lockout an SSS clutch?
  84. #280 Which of the following statements is true about the "lockout control" on a Synchro-Self-Shifting (SSS) clutch?
  85. #287 For the GE LM2500 gas turbine engine shown in the illustration, the HP turbine 1st stage nozzle vanes are cooled by which of the following? Illustrati... illustration
  86. #289 Turbine disks are commonly attached to the shaft by which of the following methods?
  87. #290 To keep the exit pressures relatively constant across a HP turbine blade, which type of construction is generally utilized?
  88. #291 HP turbine blades are generally cooled by which of the following methods?
  89. #292 Which of the following designs is the most satisfactory method for attaching turbine blades to the rotor disk?
  90. #293 "Standard Day" conditions, as defined by the ISO, is which of the following?
  91. #297 On a propulsion marine gas turbine, if full power temperatures become excessive, what action should the operator take?
  92. #298 If the lube oil scavenge temperature exceeds 300 degrees Fahrenheit on the gas turbine engine shown in the illustration, and reducing power does NOT b... illustration
  93. #299 Accelerometers are generally used on gas turbine engines to sense which of the following?
  94. #300 Displacement, velocity and acceleration describe three types of which of the following?
  95. #302 Which of the following could cause compressor stall?
  96. #303 The two main types of compressor stall are known as what?
  97. #304 What is the term given to the condition in which cyclic pressure changes result in a repetitive failure and recovery of compressor air flow?
  98. #305 How can compressor stall be prevented?
  99. #306 Compressor surge is caused by which of the following factors?
  100. #307 When a compressor is in a stall condition, what will happen to the combustor and turbine temperatures?

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