National Maritime Center - dco.uscg.mil the marine gas turbine engine shown in the illustration, the 8th stage bleed air is used for which of the following? Illustration GT-0017

National Maritime Center Providing Credentials to Mariners

U.S.C.G. Merchant Marine Exam

Third Assistant Engineer, Unlimited

Q533 Gas Turbine Plants

(Sample Examination)

Page 1 of 23 Q533 Gas Turbine Plants

5/30/2018

U.S.C.G. Merchant Marine Exam Third Assistant Engineer, Unlimited Q533 Gas Turbine Plants Illustrations: 7

Choose the best answer to the following Multiple Choice Questions.

1. Newton's First Law of Motion states which of the following?

o (A) A body in motion will continue to stay in motion, when an equal and opposite external force is applied.

• (B) A body in a state of rest tends to remain at rest, and a body in motion continues to stay in motion at a constant speed, unless acted upon by some external force.

o (C) A body at rest will remain at rest when an external force is applied. o (D) A body in a state of rest tends to remain at rest, and a body in motion continues to stay in

motion, when an external force is applied.

If choice B is selected set score to 1.

2. Wrenches that are recommended for use on gas turbine engines should be plated with which of the following elements?

o (A) Silver o (B) Carbon o (C) Bronze • (D) Nickel

If choice D is selected set score to 1.

3. When auto-starting a gas turbine engine similar to the one shown in the illustration, a "False Start" indication will initiate if which of the following conditions occurs? Illustration GT-0016

o (A) Power turbine outlet temperature fails to reach a preset value. o (B) The power turbine fails to reach a preset RPM after the gas generator reaches a preset RPM. • (C) The gas generator rotor fails to reach a preset RPM after the starting motor has been

energized for a preset interval. o (D) The gas generator rotor fails to reach a preset RPM after the power turbine begins to rotate.

If choice C is selected set score to 1.

4. To keep the exit pressures relatively constant across a HP turbine blade, which type of construction is generally utilized?

• (A) Impulse-Reaction. o (B) Rateau. o (C) Impulse. o (D) Curtis.

If choice A is selected set score to 1.


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5. All clock positions, engine references, and enclosure references apply to viewing the gas turbine engine shown in the illustration, from which of the following locations? Illustration GT-0017

o (A) Intake end, looking toward the exhaust end. • (B) Rear (exhaust end), looking toward the intake end. o (C) Right side of the compressor to the left side. o (D) Left side of the power turbine to the right side.


6. Which of the following wrenches should NOT be used while working on a gas turbine?

o (A) Flare nut wrench. o (B) Crowfoot wrench. o (C) Box wrench. • (D) Adjustable wrench.


7. The lubrication principal utilized by the Kingsbury thrust bearing is which of the following?

• (A) Wedge-shaped oil film. o (B) Square-shaped oil film. o (C) Cylinder-shaped oil film. o (D) Free-sliding oil film.


8. Assuming at least a 500 rpm for the input shaft speed from the power turbine, as shown in the illustration, the synchronous self-shifting (SSS) clutch used on marine gas turbine main propulsion gears, requires which of the following inputs or conditions to make engagement possible? Illustration GT-0018

o (A) Availability of low-pressure air to provide control air pressure for engagement. o (B) Availability of high-pressure air to provide clutch air inflation pressure. o (C) When the input shaft speed from the power turbine falls below the output shaft speed. • (D) When the input shaft speed from the power turbine rises to the output shaft speed.


9. As shown in the illustration, the component labeled "F" would be identified as a ________. Illustration MO-0128

o (A) main condensate pump o (B) fuel oil service pump • (C) boiler water feed pump o (D) waste heat boiler circulating pump

If C choice is selected set score to 1.


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U.S.C.G. Merchant Marine Exam Third Assistant Engineer, Unlimited Q533 Gas Turbine Plants Illustrations: 7 10. What type of air seal is used in the sump and turbine areas of a gas turbine engine?

o (A) Lip-type • (B) Labyrinth-Honeycomb o (C) Fishmouth o (D) Pneumatic carbon ring


11. Each stage of an axial compressor of a gas turbine can compress the atmospheric air a total of how many times?

• (A) 1.2 times o (B) 2.2 times o (C) 3.2 times o (D) 4.2 times


12. Accelerometers are generally used on gas turbine engines to sense which of the following?

o (A) Rate of rotor speed changes. o (B) Gas generator speed with respect to power turbine speed. • (C) High frequency vibration. o (D) PLARA rate limited feedback to the FSEE.


13. The three most common types of combustors used in gas turbine engines are which of the following?

o (A) can, angular, and can-angular. o (B) can, derivative, and can-derivative. o (C) can, vortex, and can-vortex. • (D) can, annular, and can-annular.


14. The two basic types of compressors used in gas turbine engines are which of the following?

o (A) Axial and reciprocating. • (B) Centrifugal and axial. o (C) Axial and lobe. o (D) Centrifugal and reciprocating.



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15. Which of the following statements concerning fire-tube boilers is correct?

o (A) Flames impinge on the tubes. o (B) Combustion occurs in the tubes. o (C) Combustion gases flow through the tubes. o (D) Water flows through the tubes.

If choice is selected set score to 1.

16. The turbine nozzle blades convert the combustion gases heat and pressure energy into what form of energy?

o (A) Chemical • (B) Velocity o (C) Electrical o (D) Thermal


17. How do the high-velocity high-temperature gases cause the gas turbine rotor to rotate?

o (A) By increasing the velocity of the gases. o (B) By converting the high-velocity gas to low-velocity gas. • (C) By transferring velocity energy and thermal energy to the turbine blades. o (D) By creating a low-pressure area before the rotor.


18. What is the approximate percentage of air extracted from the compressor that is mixed with fuel for combustion in a gas turbine?

o (A) 12% • (B) 25% o (C) 50% o (D) 75%


19. If the lube oil scavenge temperature exceeds 300 degrees Fahrenheit on the gas turbine engine shown in the illustration, and reducing power does NOT bring the temperature within limits, the operator should do which of the following? Illustration GT-0017

o (A) Continue to operate at the reduced power level. o (B) Monitor the temperature while continuing to operate. o (C) Continue to reduce power on the engine. • (D) Shutdown the engine and troubleshoot.



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U.S.C.G. Merchant Marine Exam Third Assistant Engineer, Unlimited Q533 Gas Turbine Plants Illustrations: 7 20. What is a compressor midspan shroud?

• (A) A brace built into the middle of a rotor blade for damping. o (B) The center of a two-piece rotor blade. o (C) A method of securing stator blades. o (D) A support for the tips of the stator blades.


21. The acronym MFC represents which of the following?

o (A) Midframe compressor. o (B) Manifold fuel control. o (C) Maritime fuel congress. • (D) Main fuel control.


22. Under standard atmospheric conditions, 208.7 PSIG converts to approximately what in absolute pressure?

o (A) 104.7 PSIA • (B) 223.4 PSIA o (C) 194.0 PSIA o (D) 214.7 PSIA


23. Which of the following statements is true concerning the fuel oil ignition system of the gas turbine engine shown in the illustration? Illustration GT-0017

o (A) The igniters will de-energize when the power turbine exceeds a preset RPM. o (B) The igniters remain energized throughout the normal operation of the engine. • (C) The igniters will de-energize when the gas generator exceeds a preset RPM. o (D) The igniters will only energize if the exhaust gas temperature falls below a preset value.


24. The fuel oil system of a gas turbine engine provides all EXCEPT which of the following?

o (A) Provides accurately metered fuel for combustion o (B) Controls the angle of the variable stator vanes • (C) Acts as a cooling medium for the lube oil cooler o (D) Acts as a hydraulic medium to actuate the fuel control



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U.S.C.G. Merchant Marine Exam Third Assistant Engineer, Unlimited Q533 Gas Turbine Plants Illustrations: 7 25. Which of the following components prevent(s) objects smaller than 1/4 inch from entering the GE

LM2500 gas turbine?

o (A) Centerbody o (B) Demister pads • (C) FOD screens o (D) Inlet louvers


26. What is the purpose of the Controllable-Pitch Propeller (CPP) hydraulic oil power system?

o (A) Supplies high-pressure oil for both propeller blade actuation and stern tube sealing. • (B) Supplies high-pressure oil for blade actuation and control oil for propeller pitch control. o (C) Supplies low-pressure oil for propeller blade actuation and control oil for propeller pitch

control. o (D) Supplies low-pressure oil for both pitch control and stern tube sealing.


27. In a single shaft, cold-end drive gas turbine, the power output speed has what relationship to the speed of the compressor?

• (A) It is the same or in a direct relationship through reduction gears. o (B) It is in an inverse relationship through reduction gears. o (C) It varies independently of compressor speed. o (D) None of the above.


28. A centrifugal flow gas turbine uses what type of combustion chamber?

o (A) double-annular o (B) annular • (C) can o (D) can-annular


29. On the marine gas turbine engine shown in the illustration, the 8th stage bleed air is used for which of the following? Illustration GT-0017

o (A) Power turbine balance piston cavity pressurization. o (B) High-pressure turbine 2nd stage nozzle cooling. • (C) Lube oil sump pressurization and cooling. o (D) Power turbine blade cooling.



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U.S.C.G. Merchant Marine Exam Third Assistant Engineer, Unlimited Q533 Gas Turbine Plants Illustrations: 7 30. What is the purpose of the spring in a lip-type oil seal?

• (A) To keep the neoprene snugly fit around the shaft o (B) To seal against maximum fluid pressure o (C) To prevent air from entering the sump o (D) To remove burrs and dirt from the shaft


31. An open cycle gas turbine engine is best described by which of the following statements?

o (A) Working fluids are taken in, transformed, and then recuperated. o (B) Energy is added externally. o (C) Energy is neither created nor destroyed and the cycle is therefore perpetual. • (D) Working fluids are taken in, transformed, and then discarded.


32. Power is defined as which of the following?

o (A) Work performed through a distance. o (B) The rate of applying a force. • (C) The rate of doing work. o (D) Force applied through a distance.


33. What are two common methods of power turbine blade retention?

o (A) Fir-tree and bolting • (B) Bulb and dovetail o (C) Riveting and fir-tree o (D) Bulb and bolting


34. In a centrifugal compressor, which component reduces the velocity and increases the static pressure of the air?

o (A) Impeller • (B) Diffuser o (C) Eductor o (D) Volute



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35. Variable stator vanes give an axial gas turbine compressor which of the following capabilities?

o (A) Ability to maintain constant turbine primary air flow across all speeds. • (B) Ability to maximize turbine efficiency across all speeds. o (C) Ability to maximize turbine surge capacity across all speeds. o (D) Ability to maintain constant turbine compression ratio across all speeds.


36. Marine GTE fuel oil systems, as shown in the illustration, require fuel oil shutdown valves to be _________. Illustration GT-0021

• (A) piped in series o (B) piped in parallel o (C) piped in series-parallel o (D) manually operated from MPCMS


37. What type of engine starter motor is commonly found on the marine gas turbine shown in the illustration? Illustration GT-0006

o (A) AC induction motor o (B) DC series wound electric motor o (C) AC synchronous motor • (D) Hydraulic motor


38. A centrifugal compressor assembly consists of which of the following?

• (A) A rotating impeller and a stationary diffuser. o (B) Stationary vanes and rotating blades. o (C) A stationary impeller and a rotating diffuser. o (D) Rotating pistons and stationary liners.


39. What type of starter is commonly used on smaller gas turbine engines?

o (A) Air turbine • (B) Electric o (C) Hydraulic o (D) Pneumatic



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U.S.C.G. Merchant Marine Exam Third Assistant Engineer, Unlimited Q533 Gas Turbine Plants Illustrations: 7 40. Which of the following statements concerning fluid flow is true?

• (A) If a fluid flowing through a tube reaches a constriction or narrowing of the tube, the velocity of the fluid flowing through the restriction increases and the pressure decreases.

o (B) If a fluid flowing through a tube reaches a constriction or narrowing of the tube, the velocity of the fluid flowing through the restriction decreases and the pressure increases.

o (C) If a fluid flowing through a tube reaches a constriction or narrowing of the tube, the velocity of the fluid flowing through the restriction decreases and the pressure decreases.

o (D) If a fluid flowing through a tube reaches a constriction or narrowing of the tube, the velocity of the fluid flowing through the restriction increases and the pressure increases.


41. An axial compressor basically consists of which of the following?

o (A) A rotating impeller and a stationary diffuser. o (B) Rotating pistons and stationary liners. o (C) A stationary impeller and a rotating diffuser. • (D) Stationary vanes and rotating blades.


42. A turbine stage is represented by which of the following components and in which order?

o (A) Two sets of stationary vanes, one set of rotating blades. o (B) One set of rotating blades, one set of stationary vanes. • (C) One set of stationary vanes, one set of rotating blades. o (D) One set of rotating vanes, one set of stationary blades.


43. The Brayton Cycle is a series of events best described by which of the following statements?

o (A) Intake, decompression, combustion, expansion, exhaust. o (B) Intake, compression, combustion, explosion, exhaust. o (C) Intake, pressurization, ignition, exhaust. • (D) Intake, compression, combustion, expansion, exhaust.


44. The electrostatic vent fog precipitator removes oil mist from which of the following areas?

• (A) Main reduction gear o (B) Synchronous self-shifting clutch o (C) Lube oil storage tank o (D) Gas turbine engine



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U.S.C.G. Merchant Marine Exam Third Assistant Engineer, Unlimited Q533 Gas Turbine Plants Illustrations: 7 45. Which of the following designs is the most satisfactory method for attaching turbine blades to the

rotor disk?

o (A) Locking tab design. • (B) Fir-tree design. o (C) Pinning design. o (D) Retaining ring design.


46. A gas turbine engine's main lube oil system pump check valve serves to maintain system prime and perform what other function?

o (A) To increase system pressure o (B) To return oil to the main reduction gear sump • (C) To prevent reverse flow of oil through a secured pump o (D) None of the above


47. What is the term given to a process that occurs without a loss or gain of heat?

o (A) Isothermal o (B) Exothermic. o (C) Endothermic. • (D) Adiabatic


48. When working with gas turbine synthetic lube oil, which of the following safety measures should always be observed?

o (A) thoroughly wash any area of skin contact o (B) wear eye protection and rubber gloves o (C) avoid prolonged inhaling of vapors • (D) All of the above


49. What is the term used to describe the stationary vanes preceding the first stage of an axial compressor?

• (A) Inlet guide vanes. o (B) Variable inlet vanes. o (C) First stage stator vanes. o (D) Variable stator vanes.



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U.S.C.G. Merchant Marine Exam Third Assistant Engineer, Unlimited Q533 Gas Turbine Plants Illustrations: 7 50. A gas turbine engine in which exhaust gas heat energy is added to the compressor air charge before

entering the combustor, is classified as which of the following?

• (A) Regenerative cycle. o (B) ICR cycle. o (C) Reheat cycle. o (D) Combined cycle.


51. For the GE LM2500 gas turbine shown in the illustration, the 9th stage bleed air is used for which of the following? Illustration GT-0017

• (A) Power turbine cooling. o (B) High-pressure turbine second stage nozzle cooling. o (C) Sump pressurization and cooling. o (D) Compressor balance piston cavity pressurization.


52. Compressor characteristics are normally summarized in the form of which of the following?

• (A) Compressor map. o (B) Spread sheet. o (C) Straight line graph. o (D) Venn diagram.


53. Which of the following could cause compressor stall?

o (A) The angle at which the hot gases strike the turbine rotor blades is too high. o (B) The angle at which the air strikes the compressor rotor blades is too low. o (C) Air flow over the lower foil section becomes turbulent and destroys the pressure zone. • (D) The angle at which the air strikes the compressor rotor blades is too high.


54. On a GE LM2500 gas turbine powered vessel you are conducting a borescope inspection of the compressor. What is used on each compressor stage as a reference for indexing the blades?

o (A) The IGV actuator. • (B) The locking lug blades. o (C) Witness marks center punched on the #1 nozzle and blade. o (D) Scribe marks located on the stator and rotor diaphragm.



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U.S.C.G. Merchant Marine Exam Third Assistant Engineer, Unlimited Q533 Gas Turbine Plants Illustrations: 7 55. What feature is commonly used on articulated reduction gear arrangements for the correction of

misalignment between the 1st reduction gear and the 2nd reduction pinions?

o (A) Locked train shims. o (B) Torsion pads. o (C) Fixed block pads. • (D) Quill shafts.


56. Routine water washing of the gas turbine compressor shown in the illustration, is usually performed while operating under which of the following conditions? Illustration GT-0017

o (A) At 25% power. o (B) At 75% power. o (C) At 100% power. • (D) With the starter motor drive.


57. Which of the following is the principle that a magnetic speed sensor/pickup operates on?

o (A) Variations in the earth’s magnetic field are caused by ferrous materials. o (B) Vibration caused by shaft rotation can determine the speed of rotation. o (C) Force is the product of mass and acceleration. • (D) Voltage is produced when a ferrous material moves through a magnetic field.


58. What are the two principle functions of the turbine nozzle guide vanes?

o (A) Convert the heat energy of the hot gases into potential energy and direct the flow of gases to the turbine rotor blades.

o (B) Convert the potential energy of the hot gases into heat energy and direct the flow of gases to the turbine rotor blades.

• (C) Convert the heat energy of the hot gases into kinetic energy and direct the flow of gases to the turbine rotor blades.

o (D) Convert the heat energy of the hot gases into potential energy and direct the flow of gases to the compressor rotor blades.



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59. Control of the fuel oil metering valve in an automatically fired auxiliary boiler is accomplished by a __________.

o (A) pressure magnifying device in the steam coil outlet o (B) metering device in the air supply line • (C) steam pressure sensing device with linkage to the damper air vanes o (D) signal from the feed water electrode


60. Which of the following statements is true regarding centrifugal compressors?

o (A) Centrifugal compressors are complicated in design and heavy. o (B) The efficiency of a centrifugal compressor is greater than that of an axial compressor. • (C) The centrifugal compressor is frequently used on small, low power turbines. o (D) The impeller of a centrifugal compressor has a radial inlet and axial discharge.


61. Why are loose-fitting blades used on the first several stages of large axial compressors?

• (A) To minimize vibration while the engine is passing through critical speed ranges. o (B) To compensate for a malfunctioning compressor support bearing. o (C) To maintain close tolerances in the compressor. o (D) To compensate for the abrasive action of the blade tips.


62. Compared to other types of engines, what is the biggest advantage of a gas turbine engine?

o (A) Low power-to-weight ratio. o (B) Simplicity of installation. o (C) Simplicity of the control circuits. • (D) Highest power-to-weight ratio.


63. The main lubrication system utilized by the gas turbine engine shown in the illustration is what type? Illustration GT-0017

• (A) Dry sump o (B) Common drain sump o (C) Oil mist recovery sump o (D) Wet sump



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U.S.C.G. Merchant Marine Exam Third Assistant Engineer, Unlimited Q533 Gas Turbine Plants Illustrations: 7 64. (2.9.6.1-3) What is the most common type of spark igniter used on a gas turbine engine?

o (A) Delayed gap o (B) Resistive gap • (C) Annular gap o (D) Suppression gap


65. For the GE LM2500 gas turbine engine shown in the illustration, the HP turbine 2nd stage nozzle vanes are cooled by which of the following? Illustration GT-0020

o (A) 9th stage compressor air. o (B) 13th stage compressor air. • (C) 16th stage compressor air. o (D) Frame vent bleed air.


66. In a coil-type forced circulation auxiliary water-tube boiler, __________.

o (A) steam is recirculated through heating coils in the boiler o (B) unevaporated feed water is discharged through the skim tube • (C) steam demand response is comparatively rapid o (D) steam demand response is slow


67. Provisions for avoiding the buildup of ice on the intake air surfaces of a gas turbine plant can be found where?

o (A) In the stack intake ducting. o (B) In the inlet duct frame at the inlet to the engine. o (C) In the exhaust and intake ducting. • (D) Both A & B.


68. What is the term given to the condition in which cyclic pressure changes result in a repetitive failure and recovery of compressor air flow?

• (A) Surge. o (B) Laminar. o (C) Stall. o (D) Turbulence.



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U.S.C.G. Merchant Marine Exam Third Assistant Engineer, Unlimited Q533 Gas Turbine Plants Illustrations: 7 69. The gas generator section of the GE LM2500 gas turbine is composed of all of the following

components EXCEPT which of the following?

o (A) Two-stage HP turbine o (B) FOD screen o (C) Bellmouth • (D) Six-stage LP turbine


70. How is the clutch shown in the attached illustration engaged? Illustration GT-0018

o (A) Clutch engages automatically once the output assembly begins rotating. o (B) Pneumatic pressure from the compressor engages the clutch. • (C) Clutch engages automatically when input shaft flange is rotating faster than the output

assembly. o (D) Clutch is engaged manually prior to start up.



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6/10/2015

GT-0006

Adapted for testing purposes only from Gas Turbine Systems Supervisor

NAVEDTRA 14111

Further reproduction prohibited without permission. Page 17 of 23 Q533 Gas Turbine Plants


6/25/2015

GT-0016

Adapted for testing purposes only from Gas Turbine Systems Technician (Electrical) 3/

Gas Turbine Systems Technician (Mechanical) 3, Volume 2

NAVEDTRA 14114



6/26/2015

GT-0017



NAVEDTRA 14114

Further reproduction prohibited without permission.

EE DD

FF

CC

BB AA



6/29/2015

GT-0018



NAVEDTRA 14113



7/1/2015

GT-0020



NAVEDTRA 14114



7/7/2015

GT-0021



NAVEDTRA 14114

Further reproduction prohibited without permission.

A

B 1 2

3

5

4 6



10/20/2016

MO-0128

Adapted for testing purposes only

Further reproduction prohibited without permission Page 23 of 23 Q533 Gas Turbine Plants

Documents

National Maritime Center - dco.uscg.mil the marine gas turbine engine shown in the illustration, the 8th stage bleed air is used for which of the following? Illustration GT-0017