DDE – 1000/4000 HP, Revision & Practice Exams

While air is being compressed in a centrifugal flow gas turbine, what happens to the direction of air flow?

1. Changes only at the compressor discharge.
2. Changes only at the compressor inlet.
3. Changes at each separate component. ✓
4. Changes only once from inlet to outlet.

Two functions of the compressor stator vanes include which of the following?

1. Direct air flow to each rotor stage at the correct angle and deliver air to the combustor at the correct velocity and pressure. ✓
2. Direct air flow to rotor blades at the correct angle and are shaped to cause a velocity increase and a pressure decrease.
3. Direct air flow to rotor blades at the correct angle and are shaped to produce a velocity increase and maintain a constant pressure.
4. Direct air flow to rotor blades at the correct angle and are shaped to maintain a constant velocity and produce a pressure increase.

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

1. can ✓
2. annular
3. can-annular
4. double-annular

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

1. can, derivative, and can-derivative.
2. can, angular, and can-angular.
3. can, annular, and can-annular. ✓
4. can, vortex, and can-vortex.

The circle of turbine stationary vanes that convert pressure and thermal energy to velocity energy and direct the combustion gases in the direction of turbine wheel rotation is referred to as what?

1. Nozzle assembly. ✓
2. Diffuser assembly.
3. Rotor assembly.
4. Compressor assembly.

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

1. Synchronous self-shifting clutch
2. Lube oil storage tank
3. Main reduction gear ✓
4. Gas turbine engine

You are preparing for a borescope inspection of an LM2500 gas turbine engine. You are reviewing the correct geometric orientation nomenclature which includes which of the following?

1. All references left, right, and radial are orientated as viewed from aft looking forward on the engine. ✓
2. All references left, right, and radial are orientated as viewed from forward looking aft on the engine.
3. All references are made from the combustor section, forward to the HP turbine and aft to the power turbine.
4. All references are made from the combustor section, aft to the HP turbine and forward to the power turbine.

The wooden plug fitted tightly in the vent of a damaged tank may prevent the tank from __________.

1. collapsing
2. developing free surface moments
3. developing free surfaces
4. filling completely ✓

Which of the following statements is true concerning an immersion suit and its use?

1. Only a light layer of clothing may be worn underneath.
2. They provide sufficient flotation to do away with the necessity of wearing a life jacket. ✓
3. They should be tight fitting.
4. A tear in the suit will not appreciably reduce its value.

A simple precaution to reduce the possibility of accidental fires in the paint locker, is to __________.

1. label the fixed firefighting system
2. store paint cans on metal shelves only
3. not allow oily rags to accumulate in the space ✓
4. place a portable fire extinguisher immediately outside the locker

The longer an oil fire is permitted to burn, the __________.

1. easier it is to control
2. easier it is to extinguish
3. harder it is to extinguish ✓
4. less chance there is of reignition

If the water level as indicated by the gauge glass of an auxiliary boiler is in question, it should be blown down. Which of the following statements represents the proper procedure for performing a gauge glass blow down?

1. The gauge glass should be blown down twice; first with the upper cut-out valve open and then with the lower cut-out valve open.
2. The gauge glass should be blown down twice; first with the lower cut-out valve open and then with the upper cut-out valve open. ✓
3. The gauge glass should be blown down once with both the upper cut-out and lower cut-out valves open simultaneously.
4. The gauge glass should be blown down once with the lower cut-out valve open.

The acronym CDP stands for which of the following?

1. Compressor Discharge Pyrometer.
2. Choke Down Point.
3. Coupling Disassembly Point.
4. Compressor Discharge Pressure. ✓

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

1. By increasing the velocity of the gases.
2. By transferring velocity energy and thermal energy to the turbine blades. ✓
3. By converting the high-velocity gas to low-velocity gas.
4. By creating a low-pressure area before the rotor.

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

1. Thermal
2. Kinetic ✓
3. Chemical
4. Electrical

After measuring the length to which a section of shoring should be cut, you should cut the shoring __________.

1. approximately 1/2 inch longer than the measured length to allow for trimming
2. approximately 1/2 inch shorter than the measured length to allow for the use of wedges ✓
3. approximately 1/2 inch shorter per foot of the measured length to allow for wet expansion
4. to the same length as the measured length

Which of the components listed are interchangeable between different backpack self-contained breathing apparatus produced by various manufacturers?

1. The facepiece
2. The regulator
3. The air cylinder ✓
4. All of the above

The hand brake of a lifeboat winch is __________.

1. manually disengaged when hoisting a boat
2. applied by dropping the counterweighted lever ✓
3. controlled by the centrifugal brake mechanism
4. automatically engaged if lowering speed is excessive

The most likely location for a liquid cargo fire to occur on a tanker would be __________.

1. In the amidships house
2. At the main deck manifold
3. At the vent header
4. In the pumproom ✓

A hand portable CO2 fire extinguisher is effective on burning oil only __________.

1. To prevent rekindling
2. If applied promptly ✓
3. If applied in connection with foam
4. If attempts to extinguish the fire with low velocity fog have failed

In the presence of an open flame or hot surfaces, chlorinated fluorocarbon refrigerants decompose and form what chemical substance?

1. water vapor
2. phosgene gas ✓
3. carbon monoxide
4. petroleum crystals

Both the direction of flow and fluid flow rate of a variable displacement radial piston pump are determined by the relative positions of the __________.

1. floating ring and pump shaft
2. floating ring and cylinder body ✓
3. pump shaft and horizontal ports
4. pump shaft and central valve

A vessel is in compliance with federal regulations regarding the discharge of sewage by __________.

1. treating sewage in an approved system
2. holding all sewage onboard
3. pumping the sewage ashore to an approved container
4. all of the above ✓

Which of the procedures or conditions listed could result in damaging a transistor beyond repair?

1. Providing insufficient voltage to the input circuit.
2. Installing a transistor whose current rating exceeds the design circuit current.
3. Providing incorrect polarity to the collector circuit. ✓
4. Applying silicone grease between the heat sink and the transistor mounting.

When configuring a digital multimeter as an ohmmeter, what will MOST likely be displayed on the screen when the test leads are shorted together?

1. A reading of "OL" ohms will be displayed.
2. A reading of residual test lead and internal resistance will be displayed (typically .2 to .5 ohms).
3. A reading of 0 ohms will be displayed.
4. B or C could be correct depending upon the digital multimeter. ✓

When a battery-operated megohmmeter (insulation tester) is used to perform a dielectric absorption test, the resistance is measured and recorded from each conductor to ground each minute for 10 consecutive minutes. What condition accounts for a gradual rise in resistance each successive minute?

1. The insulation has direct continuity with ground.
2. The insulation is in good condition. ✓
3. The insulation is cracked and otherwise deteriorated.
4. The insulation is contaminated with moisture.

As the electrolyte level in the cells of a lead-acid battery evaporates over time, what will tend to happen to the specific gravity of the electrolyte in the cells as the level drops due to evaporation?

1. The specific gravity of the electrolyte will increase as only the water will evaporate from the electrolyte solution. ✓
2. Although the specific gravity will change due to evaporation, there is no predictable tendency either way.
3. The specific gravity of the electrolyte will remain unchanged as both the water and sulfuric acid will evaporate from the electrolyte solution.
4. The specific gravity of the electrolyte will decrease as only the sulfuric acid will evaporate from the electrolyte solution.

The arc resulting from the tripping of a circuit breaker is prevented from damaging the contacts. How is this done?

1. extinguishing the arc by means of an arc chute ✓
2. an inverse timed thermal trip for short circuit currents
3. designing the contacts to open slowly
4. instantaneous magnetic trip for overload currents

In which of the following branch circuits types would time lag fuses (or dual-element fuses) be MOST likely used?

1. emergency lighting circuits
2. general alarm circuits
3. motor starting circuits ✓
4. main lighting circuits

A boiler safety valve must be capable of __________.

1. Closing with a chattering motion to free scale deposits from the seats
2. Opening gradually above a designated pressure
3. Remaining open until all pressure in the steam drum is relieved
4. Remaining open until a preset pressure drop occurs ✓

The boiler water gauge glasses should be blown down __________.

1. twice each day on the midnight and afternoon watches
2. when the boiler water level changes in a steaming boiler
3. every 12 hours of steady boiler steaming operation
4. when you are in doubt about the water level ✓

Treatment of boiler feedwater for the control of hardness is necessary to prevent __________.

1. foaming
2. excessive feedwater alkalinity
3. carryover
4. waterside scale deposits ✓

The correct radial clearances between the rotor and the casing in a propulsion turbine are maintained by the turbine __________.

1. diaphragms
2. interstage packing
3. thrust bearing
4. journal bearings ✓

Which of the filters listed will deplete the additives in lubricating oil?

1. Extended area membrane filter
2. Cloth bag extractor
3. Absorbent filter
4. Adsorbent filter ✓

A Kingsbury, or pivot shoe type thrust bearing, can bear much greater loads per square inch of working surface than can parallel surface bearings because provisions are made in the Kingsbury bearing __________.

1. to allow the leveling plates to pivot on the collar when thrust loads are applied
2. for the shoes to tilt slightly, thereby allowing the formation of a wedge-shaped oil film under a thrust load ✓
3. for adjusting the filler piece thickness behind the pivotal-shoes to give a more accurate fit
4. for automatically adjusting clearances to the correct value when wear occurs

The flash point of a residual fuel oil should be used to determine the highest temperature to which the oil may be heated __________.

1. in a storage tank ✓
2. for centrifuging
3. for atomizing
4. in the recirculating line

Turbine casing flanges are sometimes provided with a system of joint grooving to __________.

1. form a labyrinth seal between the casing halves
2. ensure perfect alignment of casing halves
3. inject sealing compound between the casing halves ✓
4. increase contact pressure between the casing halves' flanges

The splits located in the halves of main reduction gear bearings are aligned at an angle to the horizontal in order to resist __________.

1. oil loss
2. wiping ✓
3. axial stress
4. steam loss

When checking the cylinder jacket water cooling expansion tank level on a main propulsion diesel engine on your towing vessel while underway on a coast-wise voyage, what should be the expansion tank level?

1. The level should be in the upper part of the sight glass when the engine is at operating temperature. ✓
2. The level should be out of sight high in the sight glass when the engine is at operating temperature.
3. The level should be in the lower part of the sight glass when the engine is at operating temperature.
4. The actual level is unimportant as long as it is visible in the sight glass when the engine is at operating temperature.

The main propulsion diesel engines used to power the ship-docking tug to which you are assigned are started with vane-type air-starting motors designed to operate at 250 psig. The in-line lubricator should provide 3 drops of oil per cranking minute, as long as the in-line lubricator oil viscosity is as specified. If the start air pressure is within the normal range and the oil viscosity is correct, but the oil injection rate is only 1 drop per minute, what should be done?

1. The starting air pressure supplied to the air-starting motors should be increased.
2. The in-line lubricator oil injection metering needle valve should be further closed.
3. The oil in the in-line lubricator should be replaced with oil of lower viscosity than specified.
4. The in-line lubricator oil injection metering needle valve should be further opened. ✓

The diesel engines on your towing vessel are all protected with dry-type air filters. The air filters should be inspected and replaced in accordance with manufacturer instructions. What is the generally accepted criteria that would dictate when filter replacement becomes necessary?

1. The air filter element should be replaced when the pressure rise across the element increases above the specified maximum.
2. The air filter element should be replaced when the pressure rise across the element decreases below the specified minimum.
3. The air filter element should be replaced when the pressure drop across the element decreases below the specified minimum.
4. The air filter element should be replaced when the pressure drop across the element increases above the specified maximum. ✓

You are replacing an automotive type cooling water thermostat on one of the diesel generator sets on your ship docking tug. The markings on the original thermostat indicate that it was set to begin opening at 180oF. Which of the following thermostats marked for Celsius would be a replacement that comes closest to the value at which opening begins as compared to the original thermostat?

1. 70oC
2. 80oC ✓
3. 90oC
4. 100oC

The two-stroke cycle main propulsion engines on the harbor tug to which you are assigned are fitted with turbochargers for scavenging purposes. Assume that you are checking the air box drains in an installation that is valved with external drain piping to a drains tank. When you open the air box drain valves, no drainage occurs when in fact there is an accumulation of oil and moisture on the floor of the air boxes. What should you do?

1. Blow through the drain openings with compressed air to clear the drains.
2. Increase the crankcase pressure to blow the air box drain openings clear.
3. Increase the air box pressure to blow the air box drain openings clear.
4. Mechanically poke through the drain openings with a rod to clear the drains. ✓

A main-propulsion diesel engine on your ship docking tug has experienced a safety shutdown due to high lubricating oil temperature. What is the appropriate response?

1. Allow the engine to cool off for two minutes, then restart and monitor the lubricating oil temperature to verify the cause of the shutdown.
2. Allow 2 hours for the engine to cool down before attempting to inspect the engine and correct the cause of the trip before attempting to restart the engine. ✓
3. Immediately restart the engine, and monitor the oil temperature to verify the cause of the shutdown.
4. Immediately perform the engine inspections to determine the cause of the high oil temperature safety shutdown.

When rolling over a main engine on your river push boat prior to starting with the cylinder test valves open to expel any fluids accumulated within the cylinders, a rather large amount of water is discharged. What is the appropriate response?

1. Start the engine, but monitor all fluid levels very closely, especially that of the jacket water.
2. Start the engine, but maintain the jacket water expansion tank level higher than normal.
3. Start the engine, but run the engine with the cylinder test valves cracked slightly open.
4. Do not allow the engine to be started until the cause of the water discharge has been determined and corrected. ✓

Suppose each of the main propulsion engines on your harbor assist tug is equipped with a variable speed governor equipped with a solenoid actuated shutdown device. After a high temperature alarm, after continuing to rise, what is the most likely engine high temperature condition that would initiate a safety trip shutdown?

1. High charge air temperature
2. High fuel temperature
3. High exhaust temperature
4. High jacket water temperature ✓

Diesel engine closed, re-circulating cooling water systems are particularly prone to cavitation corrosion/erosion. Which of the listed cooling system/engine components has surfaces in contact with the coolant that are most susceptible to this type of corrosion and erosion?

1. Engine exhaust cooling water jackets
2. Cylinder head cooling water passages
3. Wet-type cylinder liners ✓
4. Cylinder cooling water jackets