Third Assistant Engineer, Revision & Practice Exams

In a closed feed and water cycle, which of the conditions listed could prevent vacuum from reaching the desired level?

1. Steam pressure to air ejectors maintained at 10 psig above designed supply pressure.
2. Condensate recirculating back to the condenser during maneuvering.
3. Steam leaking from the turbine glands.
4. Marine growth on the cooling water side of the main condenser. ✓

Which of the listed systems would be a potential source for the high-pressure drain system?

1. Fuel oil tank heating coils
2. Steam systems operating in excess of 150 psi ✓
3. Galley steam tables
4. Laundry steam pressing machines

When burning fuel oil in a boiler, a high CO2 content is desired in the stack gas because __________.

1. efficient combustion is indicated even though the heat liberated is less than the heat produced by burning to CO
2. less excess air is required to produce CO2 than CO
3. efficient combustion is indicated and the heat liberated is equal to the heat produced by the formation of CO
4. more heat is liberated by the production of CO2 than CO ✓

Fuel oil is transferred to the settling tanks for __________.

1. the purpose of removing any volatile gases present in the fuel
2. heating to the correct temperature for proper burner atomization
3. purging of any large air bubbles that have formed
4. heating to allow water and sediment to settle out ✓

Carbon dioxide dissolved in boiler water is dangerous in a modern power boiler because the gas __________.

1. combines with oxygen to cause severe waterside scaling
2. breaks the magnetic iron oxide film inside boiler tubes
3. combines with sulfates to cause severe waterside pitting
4. forms carbonic acid which attacks the watersides ✓

Water retained in the lube oil system of a main propulsion turbine installation is undesirable because it __________.

1. causes pitting of the gear teeth ✓
2. results in excessive cooling of bearing surfaces
3. causes the turbine to overspeed
4. raises the flash point of the oil to a dangerously high level

A cloudy or milky appearing lube oil sample, taken from the main lubricating oil system could be caused by __________.

1. insufficient gland sealing steam
2. excessive gland sealing steam ✓
3. insufficient cooling water to the lube oil cooler
4. excessive cooling water to the lube oil cooler

Which of the following operational practices is helpful in avoiding the accumulation of condensate in the main reduction gear casing?

1. The temperature of the lubricating oil should not exceed the gear manufacturer's recommendation when the unit is operating at full load.
2. Avoid applying gland sealing steam to the low-pressure turbine until you are ready to start up the first stage air ejector.
3. Always ensure that the lubricating oil pressure is 14-17 psi when operating in unusually cold waters.
4. After the main unit is secured, lubricating oil should be circulated until the temperature of the oil and reduction gear casing approximates the engine room temperature. ✓

Fuel combustion in a diesel engine cylinder should begin just before the piston reaches top dead center and should __________.

1. end at bottom dead center
2. end when fuel injection has been completed
3. continue through the afterburning period ✓
4. be completed exactly at top dead center

Differential needle valves used in fuel injectors are directly closed by __________.

1. spring force ✓
2. cam action
3. firing pressure
4. fuel oil pressure

Because of the close tolerances used in diesel engine fuel oil pumps, a worn plunger requires __________.

1. grinding the spare plunger to the barrel
2. replacing the plunger and the barrel ✓
3. highly polishing both the plunger and barrel
4. replacing plunger only

Which of the automatic boiler controls listed should be tested prior to lighting off an auxiliary boiler?

1. Low water level cutoff switch ✓
2. Voltage output of the ignition transformer
3. Automatic bottom blow valve
4. Insulation resistance readings in the ignition system high tension leads

A variable capacity, pressure atomizing, fuel oil burner functions to __________.

1. maintain a constant fuel temperature
2. provide a wide range of combustion ✓
3. provide a constant fuel return pressure
4. maintain smokeless fuel oil atomization

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 turbine nozzles convert heat and pressure energy to velocity energy by means of which of the following?

1. Deflection process.
2. Convergent process. ✓
3. Divergent process.
4. Convergent-Divergent process.

In a compartment that has been completely flooded with water, the greatest pressure will be exerted __________.

1. along the top of the bulkhead
2. at a point that is one-third from the bottom of the bulkhead
3. along the bottom of any bulkhead ✓
4. at the vertical center of the bulkhead

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 ✓

Hazardous conditions exist which may result in spontaneous combustion when __________.

1. oil-soaked rags are stowed in the machine shop ✓
2. powdered aluminum is stowed dry
3. dry metal turnings accumulate
4. all of the above

Which of the listed characteristics applies to a semi-portable CO2 system?

1. Each cylinder must weigh less than 50 pounds.
2. It has distribution piping installed permanently.
3. The cylinders are mounted horizontally.
4. It has a portable hose and nozzle. ✓

The most important characteristic of a fire extinguishing agent to be used on electrical fires is for the agent to be __________.

1. easily removable
2. flame resistant
3. non-conducting ✓
4. wet

One of the main concerns when fighting a galley fire is __________.

1. contaminating food with extinguishing agent
2. spreading of fire through the engineering space
3. the igniting of a grease fire in the range hood ventilation system ✓
4. the loss of stability

Which of the following statements is true regarding oxygen indicators?

1. A cotton filter placed in the end of the sampling tube prevents damaging the instrument when exposed to strongly acidic gases.
2. Prolonged exposure to gases such as CO2 may affect the accuracy of the indicator. ✓
3. The instrument is capable of providing an immediate accurate reading of any space with no delay.
4. All of the above.

Before work may safely commence on a high voltage system, what must first be done after disconnection and isolation?

1. The circuit must be tested and proved dead first with an off-line tester, then grounded.
2. The circuit must be tested and proved dead first with a live-line tester, then grounded. ✓
3. The circuit must be grounded first, then tested and proved dead with an off-line tester.
4. The circuit must be grounded first, then tested and proved dead with a live-line tester.

The theoretical minimum compression ratio necessary to ensure compression ignition in a direct injection diesel engine is __________.

1. 10 to 1
2. 12 to 1 ✓
3. 16 to 1
4. 20 to 1

Modern marine diesel engines equipped with mechanical fuel injection operate on a combustion cycle which is __________.

1. entirely constant pressure
2. entirely constant volume
3. a combination of constant volume and constant pressure ✓
4. a combination of constant temperature and constant pressure

The intake ports of a two-stroke cycle diesel engine are opened and closed by the action of the __________.

1. camshaft
2. piston movement ✓
3. exhaust valves
4. vertical drive

The start of fuel oil injection into the cylinder of a four-stroke cycle diesel engine occurs during the __________.

1. intake stroke
2. exhaust stroke
3. power stroke
4. compression stroke ✓

An eight cylinder, four-stroke cycle, single acting diesel engine has a 650 mm bore and a 1400 mm stroke. What will be the developed indicated metric horsepower if the average mean effective pressure is 30 kg/cm2 at a speed of 100 RPM?

1. 1,689 kW
2. 9,111 kW ✓
3. 12,388 kW
4. 24,776 kW

The greatest turbulence in a diesel engine cylinder is created by the __________.

1. shape of the combustion chamber ✓
2. fuel injection spray pattern
3. cylinder swept volume
4. degree of penetration of the fuel oil droplets

Bearing "crush" as applied to diesel engine main bearings, will result in __________.

1. positive seating of the bearings in their housings ✓
2. above normal operating temperatures
3. damage to the journals
4. damage to the bearings

Compared to a naturally aspirated diesel engine, a supercharged diesel engine has __________.

1. a cylinder air charge of higher pressure ✓
2. reduced cylinder mean effective pressure
3. less valve overlap
4. reduced blow-by

In a naturally aspirated diesel engine, the volume of air intake is directly associated with engine __________.

1. compression ratio
2. displacement ✓
3. fuel pressure
4. cylinder clearance volume

A naturally aspirated diesel engine at full throttle will have an intake manifold pressure __________.

1. slightly less than atmospheric pressure ✓
2. constantly decreasing as engine load increases
3. approximately equal to exhaust manifold pressure at all times
4. that is widely fluctuating

In a diesel engine exhaust system, the cooling of the exhaust gases below their dew point, will result in __________.

1. increased engine back pressure
2. sulfuric acid corrosion ✓
3. surface pitting of the turbocharger compressor blades
4. moisture impingement on the turbocharger compressor blading

Which of the listed characteristics is common to both wet and dry type diesel engine exhaust muffler systems?

1. They function as spark arresters. ✓
2. Both have a dust collecting chamber.
3. They never require any maintenance.
4. Both mufflers contain moving parts.

Wet-type exhaust silencers, that are used with some lifeboat diesel engines, utilize which design feature?

1. The exhaust gases are preheated in the silencer to reduce noise.
2. A cooling water spray and internal baffles break up the exhaust gas flow. ✓
3. The silencer is equipped with a water seal.
4. The exhaust temperature always increases when passing through the silencer.

A water jacket is placed around the exhaust manifolds of propulsion diesel engines to __________.

1. Reduce heat radiation to the engine room ✓
2. Aid in preventing turbocharger overheating
3. Condense and drain moisture from exhaust gases
4. Dampen exhaust gas pulsations in the manifold

In a diesel engine jacket water cooler, with sea water cooling the fresh water, the __________.

1. Jacket water pressure must always be less than the sea water pressure
2. Sea water temperature must never be warmer than 40°F
3. Jacket water temperature must always be less than 60°F
4. Jacket water pressure should always be greater than the sea water pressure ✓

When vapor is in contact with and remains at the same temperature as the boiling liquid from which it was generated, the vapor and liquid are said to be in which of the following?

1. sensible contact
2. saturated condition ✓
3. latent contact
4. critical state

Which of the following drawbacks of a gas turbine engine provides the greatest potential for injury to personnel?

1. High pitched noise ✓
2. Mechanical stresses the engine is subject to
3. High temperature of the exhaust gases
4. Susceptibility to foreign object damage

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

1. Energy is neither created nor destroyed and the cycle is therefore perpetual.
2. Working fluids are taken in, transformed, and then recuperated.
3. Working fluids are taken in, transformed, and then discarded. ✓
4. Energy is added externally.

Why is a gas turbine considered to operate on the Brayton cycle?

1. Combustion causes no increase in volume.
2. Combustion causes an increase in total mass flow.
3. Combustion occurs with no increase in pressure. ✓
4. Combustion causes large increase in pressure.

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. ✓

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

1. Exothermic
2. Adiabatic ✓
3. Isothermal
4. Endothermic

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

Which of the following conditions represents a particular advantage of using a positive pressure type self- contained breathing apparatus in an atmosphere that is immediately dangerous to life or health?

1. The positive pressure in the facepiece prevents contaminated air from entering the facepiece. ✓
2. The average operating time for most air cylinders is over an hour.
3. The equipment is compact and the wearer can work in confined spaces without difficulty.
4. The equipment used is lightweight and easy to wear by reducing physical strain on the wearer.

When normal operating pressure is applied to the hydraulic oil in a high-pressure system, the oil __________.

1. viscosity will decrease
2. viscosity will increase ✓
3. volume will increase
4. floc point will increase

Release of refrigerant to the atmosphere during the process of purging of air and non-condensable gases can be kept to a permissible minimum by what action?

1. purging through the top of the receiver rather than the top of the condenser
2. purging through the discharge service valve rather than the top of the condenser
3. purging through a dehydrator
4. cracking the purge valve briefly and allowing the refrigerant to re-settle between purges ✓

When checking the oil level on a reciprocating air compressor fitted with a dipstick, under what conditions should the oil level be checked?

1. With the compressor running at speed and loaded.
2. With the compressor running at speed and unloaded.
3. With the compressor in the auto mode and currently not running.
4. With the compressor in the off mode incapable of starting. ✓

What statement is true concerning the operation of continuous-level liquid level detectors?

1. Continuous-level detectors produce a digital signal inversely proportional to the liquid level in the tank.
2. Continuous-level detectors produce a digital signal proportional to the liquid level in the tank.
3. Continuous-level detectors produce an analog signal inversely proportional to the liquid level in the tank.
4. Continuous-level detectors produce an analog signal proportional to the liquid level in the tank. ✓

A reciprocating refrigeration compressor may be tested for leaking discharge valves by stopping the compressor, turning the discharge service valve all the way in, and then turning the compressor over by hand. If the discharge valves are leaking, the high-side pressure gauge will show pressures which react in which way?

1. decreasing with each stroke
2. decreasing to a vacuum
3. rising and falling with each stroke ✓
4. increasing with each stroke

What is the name of the structural member that is designed to transfer load from one deck to another?

1. Girders
2. Stiffeners
3. Pillars ✓
4. Beams

Which of the listed components of a hydraulic system would enable the pump to be temporarily shut down, and yet still provide an instantaneous source of hydraulic force?

1. Sump actuator
2. Pressure compensator valve
3. Modulator
4. Accumulator ✓

Concerning air conditioning system steam heating coils, what statement is true?

1. Steam heating coils are usually the header type and vertically installed. ✓
2. Steam heating coils are usually the serpentine type and vertically installed.
3. Steam heating coils are usually the header type and horizontally installed.
4. Steam heating coils are usually the serpentine type and horizontally installed.

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.

An open primary coil in a voltage transformer (VT) will be indicated by which of the listed conditions?

1. Overloaded secondary coil.
2. No voltage on the output of the secondary coil. ✓
3. Low resistance value on the primary coil.
4. An infinite resistance value on the secondary coil.

What is the nominal output voltage of a 6-cell lead-acid battery?

1. 6 volts
2. 7.5 volts
3. 12 volts ✓
4. 18 volts

The torque load that a synchronous motor can handle is dependent on the hold-in strength of the poles. Hence, to increase the hold-in torque, it is necessary to __________.

1. decrease the resistance of the field rheostat
2. increase the torque angle of the rotor magnets
3. increase the direct current supplied to the rotor magnets ✓
4. decrease the 3-phase armature winding current

Regulations require that shipboard cabling use stranded copper conductors. Why is copper a superior conductor compared to aluminum?

1. Even though copper has more resistance than aluminum, copper is lighter in weight than aluminum.
2. Even though copper is more corrosive than aluminum, copper is lighter in weight than aluminum.
3. Even though copper is heavier in weight than aluminum, copper has less resistance than aluminum. ✓
4. Even though copper is lower in conductivity than aluminum, copper has more resistance than aluminum.

What is the shape of the schematic symbol for an operational amplifier used in an analog circuit?

1. trapezoid
2. square
3. circle
4. triangle ✓

Periodic testing using a special sensing device may be performed to detect potentially dangerous loose or corroded bus bar and controller connections. What is the name of this testing technology?

1. infra-red thermography ✓
2. corrosion electrolysis
3. visual pyrotronics
4. electric vibro-analysis

What is an ammeter used to measure?

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

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. ✓

Circulation of water and the steam/water mixture within a natural circulation boiler is retarded by __________.

1. Large changes in steam density
2. Fluid friction in the downcomers, drums, generating tubes, and headers ✓
3. High feedwater pressure
4. Back pressure in the steam drum acting on the user tubes

Overheating of the generating tubes will occur when a boiler reaches its end point of __________.

1. Circulation ✓
2. Moisture carryover
3. Evaporation
4. Combustion

The primary operational difference between a huddling chamber type safety valve and a nozzle reaction type safety valve is the __________.

1. Principle by which blowdown is accomplished ✓
2. Manner in which lifting pressure is adjusted
3. Manner in which steam pressure causes initial valve opening
4. Difference in valve relieving capacities

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 ✓

Chemicals are added to boiler water to __________.

1. eliminate the need for blowdowns
2. prevent scale forming deposits ✓
3. stabilize feedwater if a boiler becomes salted up
4. maintain an acidic condition in the feedwater

8 ounces of oxygen, dissolved in 500,000 pounds of water, is a concentration of __________.

1. 1.0 ppm ✓
2. 4.0 ppm
3. 8.0 ppm
4. 16.0 ppm

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 ✓

What boiler water chemistry is necessary to ensure the precipitation of hard scale forming calcium?

1. Hydrazine concentrations should be at the proper level.
2. Boiler water should be slightly acidic.
3. Boiler water should have a reserve of phosphates. ✓
4. Boiler water hardness should be high.

The major reason dissolved gases are removed from boiler feedwater is because they may cause __________.

1. a false boiler water level
2. corrosive conditions in the boiler ✓
3. vapor lock in the feed pumps
4. condenser vacuum loss

Which of the following represents a significant system limitation to be aware of when a burner management system is operated in the "HAND" mode?

1. The flame failure alarm cannot function when the boiler is "HAND" fired.
2. The burner sequence control is fully automatic even in the "HAND" mode.
3. Some boiler safety interlocks are bypassed when the boiler is "HAND" fired. ✓
4. The burner is not capable of maintaining a high firing rate when the boiler is in the "HAND" mode.