DDE – Unlimited 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.

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

1. To compensate for a malfunctioning compressor support bearing.
2. To compensate for the abrasive action of the blade tips.
3. To minimize vibration while the engine is passing through critical speed ranges. ✓
4. To maintain close tolerances in the compressor.

What type of seal is used in the gearbox of a gas turbine engine?

1. Labyrinth-Windback
2. Lip-type
3. Fishmouth
4. Carbon ring ✓

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

Before any auxiliary diesel engine hydraulic starting system is opened for servicing or repair, you must __________.

1. Place all control levers in the "HOLD" position
2. Ensure that the hydraulic fluid reservoir is full
3. Block all hydraulic hoses using high-pressure covers
4. Bleed off all hydraulic pressure from the system ✓

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

1. Impulse-Reaction. ✓
2. Rateau.
3. Curtis.
4. Impulse.

What is the purpose of the spring in a lip-type oil seal?

1. To keep the neoprene snugly fit around the shaft ✓
2. To remove burrs and dirt from the shaft
3. To seal against maximum fluid pressure
4. To prevent air from entering the sump

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

1. Supplies low-pressure oil for propeller blade actuation and control oil for propeller pitch control.
2. Supplies low-pressure oil for both pitch control and stern tube sealing.
3. Supplies high-pressure oil for blade actuation and control oil for propeller pitch control. ✓
4. Supplies high-pressure oil for both propeller blade actuation and stern tube sealing.

The only hand tools that should be used on gas turbine engines are chrome plated, nickel plated, or which of the following?

1. Cadmium plated
2. Unplated ✓
3. Silver plated
4. Bronze plated

When conducting a borescope inspection, you must be aware of all of the following factors EXCEPT which?

1. The inspection areas and ports.
2. The limitations of your equipment.
3. The engineer’s experience. ✓
4. The internal reference points.

For the GE LM2500 gas turbine engine shown in the illustration, the 13th stage bleed air is used for which of the following? Illustration GT-0017

1. Power turbine balance piston cavity pressurization
2. Sump pressurization and cooling
3. Power turbine cooling
4. High-pressure turbine 2nd stage nozzle cooling ✓

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? Illustration GT-0020

1. 8th stage compressor air
2. 9th stage compressor air
3. 13th stage compressor air
4. 16th stage compressor air ✓

When fighting a shipboard fire, crew members securing doorways, hatches, and applying cooling water to adjacent decks and bulkheads, while monitoring the spread of heat and smoke, are setting a _________.

1. fire boundary ✓
2. buffer zone
3. cooling zone
4. safety perimeter

The most effective method of extinguishing a class "A" fire is by __________.

1. blanketing and smothering
2. using a sodium based dry chemical
3. quenching and cooling ✓
4. using non-conducting extinguishers

When pumping down an air conditioning system to test the low-pressure cut-out switch, assuming that the compressor is running, what should be done to initiate the test?

1. stop the compressor
2. secure the condenser
3. stop the circulating pump
4. close the "king" valve ✓

Which of the following statements is true concerning the illustrated gauge manifold set? Illustration RA-0001

1. The valves labeled "G" and "C" must both be open to read system pressures on the respective gages labeled "A" and "B".
2. Closing the valve labeled "G" isolates the port labeled "H" from the port labeled "J". ✓
3. Opening fully and back-seating the valve labeled "G" isolates the gauge labeled "A" from the port labeled "H".
4. Closing the valve labeled "G" isolates the port labeled "H" from the gauge labeled "A".

A device used to hold open the refrigeration compressor suction valve during starting to reduce the compression load is called what?

1. relief valve
2. discharge line bypass
3. suction line bypass
4. cylinder unloader ✓

What is an ammeter used to measure?

1. continuity
2. current ✓
3. resistance
4. voltage

In the illustration of the one-line distribution system diagram, if at sea the 450 VAC section of the main switchboard experiences a complete loss of power, what statement is true concerning the operation of the emergency diesel-generator? Illustration EL-0014

1. It will automatically start but the automatic bus transfer device must be manually shifted to "Emergency Power" to supply the 450 VAC section of the emergency bus.
2. It will automatically start and automatically supply power to the 450 VAC section of the main bus through the automatic bus transfer device.
3. It must be manually started but once running will automatically supply power to the 450 VAC section of the emergency bus through the automatic bus transfer device.
4. It will automatically start and automatically supply power to the 450 VAC section of the emergency bus through the automatic bus transfer device. ✓

Which of the following methods should be used to dress the face of silver-plated contacts?

1. Burnishing with a burnishing tool
2. Filing with a mill file
3. Knurling with a knurling tool
4. Sanding with 400 grit sandpaper ✓

When raising steam on a cold boiler under normal conditions, you should always __________.

1. Take 24 hours to raise steam
2. Use a large orifice burner sprayer plate to start
3. Raise steam within one hour or less
4. Use a small orifice burner sprayer plate to start ✓

When fighting a liquefied natural gas fire, you should __________.

1. use only carbon dioxide
2. secure the source of gas, then extinguish the fire ✓
3. extinguish the fire, then secure the source of gas
4. use only dry chemical

When preparing to pump flammable liquids with a centrifugal pump, you should __________.

1. have a standby pump running with the discharge valve closed
2. check for gland leakage and any fire hazard ✓
3. draw a small quantity of liquid to prime the pump
4. lift the relief valve by hand to check its operation

What type of main reduction gear arrangement prevents independent axial and rotational movement of the pinions?

1. Locked train ✓
2. Unlocked train
3. Hydraulic suspension
4. Independent suspension

The service life of a worn aluminum piston for an auxiliary diesel, for which no spares are readily available, can be extended by __________.

1. turning down the piston skirt to concentric values
2. knurling the piston skirt surface ✓
3. building up the piston skirt with a liquid epoxy material and then re-machining
4. increasing the dimensions of the ring land grooves

Water in the fuel supply to a steaming boiler can be detected by __________.

1. Observation of the fuel oil heater drains
2. Sputtering of the fires ✓
3. Panting of the casing
4. Dense white smoke being observed in the periscope

The purpose of the mica used in a boiler water gauge glass assembly is to prevent __________.

1. Leakage from the glass
2. Etching of the glass ✓
3. Overheating of the glass
4. Light refraction in the glass

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

1. Lube oil sump pressurization and cooling ✓
2. High-pressure turbine 2nd stage nozzle cooling
3. Power turbine balance piston cavity pressurization
4. Power turbine blade cooling

What effect does preheating, concurrent heating, or post heating have on welding a joint?

1. Increasing the temperature gradient in the weld area and intensifying internal stresses.
2. Increasing the temperature gradient in the weld area and relieving internal stresses.
3. Decreasing the temperature gradient in the weld area and relieving internal stresses. ✓
4. Decreasing the temperature gradient in the weld area and intensifying internal stresses.

When using foam, a "Class B" fire is extinguished by __________.

1. cooling the surface
2. smothering the fire ✓
3. replacing the fuel
4. all of the above

Which of the following statements is true concerning carbon dioxide when used as a fire extinguishing agent?

1. Carbon dioxide should be applied slowly to a large engine room fire.
2. Its smothering effect is excellent for class "B" fires. ✓
3. Its total cooling effect is far greater than water.
4. Carbon dioxide is corrosive when exposed to fire.

If a fire occurs in an electric cable, in which the inner layers of insulation, or the insulation covered by armor is burning, you should __________.

1. Cut the cable with an insulated cable cutter
2. Secure power to the cable
3. Separate the two ends
4. All of the above ✓

If you see an individual fall overboard, what is the FIRST thing you should do?

1. hail "Man Overboard"
2. pass the word to the bridge
3. throw a life ring overboard ✓
4. sound three prolonged blasts

A health hazard term listed on a Safety Data Sheet (SDS) that indicates allergic-like reaction in some people after repeated exposure is __________.

1. sensitizer ✓
2. pyrophoric hazard
3. skin contact hazard
4. oxidizer

In cleaning up an oil spill, the use of straw or reclaimed paper fibers would be an example of which type of oil removal?

1. Absorbent removal ✓
2. Chemical agent removal
3. Mechanical removal
4. None of the above

Which of the substances listed can be used to shield sensitive equipment from static magnetic fields?

1. Bakelite
2. Iron ✓
3. Glass
4. Mica

Ships requiring extremely rapid maneuvering response using propeller shaft speed and direction as the sole means of controlling propeller thrust are most likely to use what type of drive system?

1. Diesel-electric drive ✓
2. Direct or geared diesel drive
3. Steam turbine geared drive
4. Gas turbine geared drive

What would be the indication of a grounded switch or cable as measured by a megohmmeter?

1. "zero" ✓
2. being unsteady in the high range
3. infinity
4. being unsteady in the low range

Prior to starting a main propulsion diesel engine fitted on your salvage tug, it has been determined that the transfer of make-up oil is required. At what checked level should you stop adding make-up oil?

1. When the oil level rises to the ADD mark on the side of the dipstick marked ENGINE STOPPED and OIL COLD.
2. When the oil level rises to the FULL mark on the side of the dipstick marked ENGINE STOPPED and OIL COLD. ✓
3. When the oil level rises to a level well above the FULL mark on the side of the dipstick marked ENGINE STOPPED and OIL COLD.
4. When the oil level rises to the between the ADD and FULL marks on the side of the dipstick marked ENGINE STOPPED and OIL COLD.

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. ✓

When interpreting the engine lube oil supply header pressures for the main engines on your river push boat, what statement is true assuming that the lube oil pump is engine-driven?

1. As the lube oil temperature increases, the supply header pressure tends to decrease, and as the engine rpm increases, the supply header pressure tends to increase. ✓
2. As the lube oil temperature increases, the supply header pressure tends to increase, and as the engine rpm increases, the supply header pressure tends to decrease.
3. As the lube oil temperature increases, the supply header pressure tends to increase, and as the engine rpm increases, the supply header pressure tends to increase.
4. As the lube oil temperature increases, the supply header pressure tends to decrease, and as the engine rpm increases, the supply header pressure tends to decrease.

The harbor tug to which you are assigned has diesel generators fitted with injectors with the operating principle as shown in the illustration. What statement is true concerning the metering principle used in this system? Illustration MO-0146

1. The amount of fuel injected is dependent upon the distance of plunger travel.
2. The amount of fuel injected is dependent upon the pressure of the inlet fuel to the injector and the length of time the orifice is open during metering. ✓
3. The amount of fuel injected is dependent upon the cylinder compression pressure and the cylinder compression temperature.
4. The amount of fuel injected depends upon the injector pre-load torque setting.

The freshwater cooling systems serving the main engines on your harbor tug are arranged as shown in the illustration. If the fresh water thermostatic control valve fails in the position where 100% of the flow from flange "A" is permanently ported to flange "B" and flange "C" is permanently blocked, while starting and warming the engine with no load, what would be the resulting warm up time period? Illustration MO-0137

1. With no load, the engine would require a much shorter than normal time frame to warm up.
2. With no load, the engine would require a relatively normal time frame to warm up. ✓
3. With no load, it is not possible to describe the time frame required to warm up the engine.
4. With no load, the engine would require a much longer than normal time frame to warm up.

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. ✓

The lubricating oil system supporting the main propulsion reduction gear on the ship-docking tug to which you are assigned is fitted with a lube oil strainer as shown in the illustration. What strainer attribute will dictate the degree of filtration in terms of the particle size capable of being filtered? Illustration MO-0057

1. The dimensions of the triangular oil passages in each disc conveying the strained oil upward
2. Vertical spacing between the metal discs as determined by the thickness of the cleaner blades ✓
3. The length of the oil sump enclosing the straining element
4. The number of discs in the disc-stack making up the straining element

The escort tug to which you are assigned is fitted with hydraulic clutches similar to that shown in the illustration. If the time required for the clutch to disengage is unacceptably long, which of the following conditions would most likely be responsible for this? Illustration MO-0089

1. Clutch operating fluid is maintained at too low a temperature.
2. Fluid clutch sump level maintained at too high a level.
3. Clutch operating fluid is maintained at too high a temperature.
4. Solid contaminants are present in the hydraulic fluid. ✓

The main engines on your harbor tug are protected with a low crankcase oil level detector protective device designed to provide an alarm when the main sump oil level drops below a certain level. It is malfunctioning, and upon investigation you determine from the technical manual that the oil level detector is a sealed unit. What statement best represents the best strategy to remedy this situation?

1. The oil level detector is adjusted just as if it was an unsealed unit, but the seals must be re-established before placing the unit back into operation.
2. The oil level detector is adjusted just as if it was an unsealed unit, without regard to any seals associated with the unit.
3. The oil level detector seals must be broken before adjustments can be made, as long as new seals are established before placing the unit back into operation.
4. The oil level detector must be replaced with a new detector if it is found to be defective, since field adjustments are not possible on this type of unit. ✓

The rated speed of the main propulsion diesel engines on your towing vessel is 900 rpm. The installed centrifugal over speed trip device similar to the one shown in the illustration is designed to shut down the engine at 110% of rated speed. Upon testing the over speed trip device, you determine that the actual shutdown occurs at 945 rpm. Which of the following would account for this? Illustration MO-0101

1. The throw-out weight (item 10) pivot bolt (not labelled) is binding within the counterweight (item 1 through 9) drilling.
2. The compression spring (item 12) was excessively compressed when the over speed trip was last set.
3. The throw-out weight (item 10) link bolt (item 15 and 16) is binding within the spring guide (item 14) drilling.
4. The jam nut was not properly tightened against the adjusting nut (items 13) when the over speed trip was last set. ✓

When cleaning burner atomizers associated with an oil-fired auxiliary boiler fitted on your harbor tug, which of the following metals would be recommended to use in fabricating a tool for the purposes of carbon removal?

1. Tungsten
2. Chrome-moly steel
3. Copper ✓
4. Titanium

The engine manufacturer for the main engines used on your harbor tug specifies a supplemental coolant additive consisting of molybdate and nitrite be used to supplement the heavy-duty antifreeze for the closed, re-circulating freshwater cooling system. A test-strip comparison chart as shown in the illustration is used for coolant testing purposes. If the molybdate concentration color corresponds to row 2 and the nitrite concentration color corresponds to column B, what statement is true? Illustration MO-0211

1. The molybdate and nitrite concentrations levels are too low, and additional supplementary coolant additive is required. ✓
2. The molybdate and nitrite concentrations levels are too high, and a portion of the coolant must be drained and replaced with fresh water.
3. The molybdate and nitrite concentrations levels are within acceptable limits, and no further correction is required.
4. It is not possible to determine the molybdate and nitrite concentration levels from the information given.

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. ✓

The river push boat to which you are assigned is fitted with generator engines as partly shown in the illustration. What statement is true concerning the cylinders? Illustration MO-0163

1. The cylinder walls are integral (non-replaceable) to the cylinder block.
2. The cylinder liners are of the wet type and are replaceable inserts. ✓
3. The cylinder liners are of the jacketed type and are replaceable inserts.
4. The cylinder liners are of the dry type and are replaceable inserts.

The river push boat to which you are assigned has diesel generators fitted with intake and exhaust systems as shown in the illustration. What does the component labeled "3" represent? Illustration MO-0176

1. Exhaust manifold
2. Charge air manifold
3. Wet muffler
4. Charge air cooler ✓

When preparing to change the oil of the speed control governor of one of the main propulsion engines on your towboat, you should consult the governor instruction manual to determine the proper viscosity of the oil to use. What is the primary factor that will determine the recommended viscosity?

1. The operating oil temperature range of the governor. ✓
2. The output power of the governor as expressed in inch-pounds.
3. The maximum rated power output of the engine.
4. The speed range (from idle to maximum governed speed) of the engine.

Suppose the generator set drive engines on your ship docking tug are fitted with hydraulic isochronous governors such as shown in the illustration. How is the speed set point conveyed from the generator control panel on the main switchboard conveyed to the governor fitted on the diesel engine? Illustration MO-0160

1. Hydraulically via tubing connections
2. Mechanically via cable connections
3. Pneumatically via tubing connections
4. Electrically via wire connections ✓

The salvage tug to which you are assigned is fitted with a totally pneumatic propulsion control system as shown in the illustration. If the astern clutch fails to engage from all control locations, but the ahead clutch properly engages from all control locations, which of the following system faults best accounts for these symptoms? Illustration MO-0168

1. The ahead clutch engagement pilot air tubing has separated from the clutch actuator 4-way control valve at the clutch control panel.
2. The control lever at the pneumatic remote-control station has a blocked astern clutch engagement pilot port.
3. The astern clutch engagement pilot air tubing has separated from the clutch actuator 4-way control valve at the clutch control panel. ✓
4. The control lever at the engine room control station has a blocked astern clutch engagement pilot port.

The rate of heat transfer in a water-tube boiler can be increased by __________.

1. operating the boiler at less than normal water level
2. installing fins on the firesides of water-tubes ✓
3. increasing the amount of excess air to the burners
4. treating the boiler water with chemical oxygen scavengers

Boiler refractory previously baked out and fired is most sensitive to __________.

1. sustained high furnace temperature
2. rapid heating
3. radiant heat of the burner
4. rapid cooling ✓

Which of the following is the best reason for opening the air cock when draining a water-tube boiler?

1. Water flows out of the boiler too rapidly with the air cock closed.
2. With the air cock open, the boiler drains without producing a vacuum. ✓
3. Air coming into the boiler will help dry out the boiler's surface.
4. Air mixed with the water will create a cleansing effect in the tubes.

Before using a boiler compressed air soot blower system, you should __________.

1. drain the soot blower pneumatic operating lines ✓
2. reduce the boiler pressure
3. decrease the forced draft fan speed
4. lower the water level

Normally a boiler water sample should be taken __________.

1. after the boiler has been blown down
2. when the boiler has been refilled with makeup
3. before the boiler has been blown down or chemicals added ✓
4. from the highest point in the feed system

The property of a fuel oil which is a measurement of its available energy, is known as its __________.

1. cetane index
2. heating value ✓
3. cetane number
4. viscosity index

What type of strainer is used in a turbine lube oil system to remove metallic particles?

1. Fuller's earth filter
2. Simplex filter
3. Magnetic basket strainer ✓
4. Metal edge strainer

When monitoring steam propulsion plant lubricating oil temperatures while underway, what represents the temperature rise across an individual bearing?

1. The temperature difference between the bearing lube oil outlet temperature and the lube oil cooler oil outlet temperature. ✓
2. The temperature difference between the bearing lube oil outlet temperature and the lube oil cooler oil inlet temperature.
3. The temperature difference between the lube oil cooler oil inlet temperature and the lube oil cooler oil outlet temperature.
4. It is NOT possible to determine individual bearing temperature rises for lubricating oil.

On main turbine propulsion units, gear-type flexible couplings are generally used between the __________.

1. second reduction and the shaft thrust bearing
2. quill shaft and high-speed pinion
3. rotor shaft and quill shaft
4. rotor shaft and pinion shaft ✓

The component shown in the illustration, labeled "I", is the __________. Illustration SE-0013

1. second reduction pinion
2. first reduction gear ✓
3. first reduction pinion
4. second reduction gear

In diesel engines, hydraulic valve lifters are used to __________.

1. obtain greater valve lift
2. reduce valve gear pounding ✓
3. increase valve operating lash
4. create longer valve duration

The Fairbanks Morse part labeled "G", as shown in the illustration, is a __________. Illustration MO-0040

1. connecting rod bushing ✓
2. bearing shell
3. piston bushing
4. connecting rod cap

The thermal energy added to the gas as it flows through the combustion section has what effect on the gas?

1. Decreases volume
2. Decreases pressure
3. Increases volume ✓
4. Increases pressure

A temperature of 69.5 degrees Fahrenheit converts to approximately what temperature in degrees Rankine?

1. 529.5 degrees R. ✓
2. 342.5 degrees R.
3. 203.5 degrees R.
4. 590.5 degrees R.

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?

1. Quill shafts ✓
2. Fixed block pads
3. Torsion pads
4. Locked train shims

While standing watch underway on a ship with the gas turbine shown in the illustration, a fire emergency stop is initiated when which of the following occurs? Illustration GT-0017

1. The fire emergency shutdown switch located on the gas turbine module is activated.
2. Either the primary or reserve gas turbine module CO2 system activates.
3. One of the UV flame detectors is activated.
4. All of the above. ✓

What type of combustor is used by the GE LM2500 gas turbine?

1. Cannular
2. Annular ✓
3. Can
4. Can-annular

The struts of the GE LM2500 compressor front frame provide passages for all of the following mediums EXCEPT which of the following?

1. Fuel oil ✓
2. Scavenge oil
3. Lube oil
4. Seal-pressurization air

Fire detecting systems on merchant vessels may be arranged to sense __________.

1. smoke
2. rate of temperature rise
3. ionized particles
4. all of the above ✓

During cargo operations, a deck fire has occurred due to a leaking cargo line. You should FIRST __________.

1. blanket the cargo spill with foam
2. prevent the spread of fire with a foam dam
3. apply CO2 on the burning fuel at its source
4. stop the transfer of cargo ✓

Your vessel is taking on bunkers from a shoreside facility. If oil begins flowing from one tank vent, which of the following actions should be taken FIRST?

1. Set out drip pans and sawdust and begin to mop up the spill.
2. Signal the shore control point to shut down. ✓
3. Close the valve on the tank vent line.
4. Open the intake valve to an adjacent tank.