USCG Third / Second Assistant Engineer Unlimited

In a two-stroke crosshead marine diesel, scavenging is the process of:

• ASweeping exhaust gas out of the cylinder with fresh charge air through the scavenge ports
• BCooling the charge air after the turbocharger to raise its density
• CMetering fuel into the cylinder just before top dead center
• DCirculating jacket water through the cylinder liner cooling spaces

Each module of the Third Assistant Engineer Unlimited examination (Q531 through Q538) requires a minimum passing score of:

• A60 percent
• B70 percent
• C80 percent
• D90 percent

Under 46 CFR 11.903(c)(9), an applicant raising grade from Third Assistant Engineer to Second Assistant Engineer Unlimited, who has already been examined at the operational level, generally:

• AMust retake all eight Q531-Q538 modules
• BMay raise grade without further written examination
• CMust pass only the Q534 safety module again
• DMust complete the 1AE01 management battery first

A fuel oil purifier (centrifugal separator) is fitted upstream of the diesel service tank primarily to:

• ARemove water and solid contaminants from the fuel before it reaches the engine
• BRaise the fuel temperature to the engine maker's injection viscosity
• CMeter the exact fuel quantity delivered to each cylinder
• DDevelop the pressure required to open the injector needle

In a four-stroke marine diesel engine, which events occur during one complete cycle (two crankshaft revolutions)?

• AIntake, compression, power, and exhaust
• BIntake and power only
• CCompression and exhaust only
• DScavenge and compression only

On a slow-speed crosshead diesel main engine, the crosshead and its guide primarily:

• ATake the side thrust from the connecting rod so the piston rod stays in line and the cran…
• BTransmit valve timing from the camshaft to the exhaust valve actuator
• CCarry the axial propeller thrust delivered by the tailshaft
• DMeter cylinder oil onto the liner running surface

Starting air for large marine diesels is commonly stored in the air receivers at approximately which pressure?

• A25 to 30 bar (about 360 to 435 psig)
• B6 to 8 bar, the same as typical control-air pressure
• C10 to 12 bar, the same as general service air
• D150 to 200 bar, the same as breathing-air cylinders

A critical safety practice for a diesel plant's starting-air system is to:

• AKeep the receivers and lines drained of oil and water so combustible deposits cannot supp…
• BLeave the starting-air master valve open while the turning gear is engaged so the engine…
• CHold the receivers at maximum pressure continuously and skip routine condensate draining
• DSet the compressor to deliver air as hot as possible so moisture stays in vapor form in t…

In a diesel fuel injection system, the function of the high-pressure fuel pump and injector is to:

• AAtomize and inject a metered quantity of fuel near top dead center for combustion
• BHeat residual fuel to its correct injection viscosity
• CPurify the fuel by removing water and sludge
• DTime the opening of the exhaust valve relative to crank angle

Heavy fuel oil for large marine diesels is heated in the final heater before the engine primarily to:

• AReduce viscosity into the engine maker's injection viscosity range
• BRaise the fuel above its flash point so it ignites more readily in the cylinder
• CSettle water and sludge out of the fuel in place of purification
• DRaise fuel pressure at the injector to the required opening pressure

Cylinder lubricating oil on a large two-stroke crosshead diesel is fed to the liner primarily to:

• ALubricate the rings and liner and neutralize acidic combustion products formed from fuel…
• BFill the crankcase sump and lubricate the main and crosshead bearings
• CProvide the hydraulic medium for the exhaust valve actuators
• DCool the piston crown through the telescopic pipe

A running diesel engine's lube-oil pressure falls below the safe minimum. The correct watchstander response is to:

• AReduce load and stop the engine in accordance with the casualty procedure if pressure is…
• BIncrease the fuel rack to raise engine speed and lift oil pressure
• CCut in the standby lube-oil pump and remain at full load while the cause is investigated
• DOpen the lube-oil filter bypass and continue at sea speed

The prime mover for a ship-service generator set on a typical motor vessel is usually:

• AA medium- or high-speed four-stroke diesel driving an alternator
• BA slow-speed crosshead two-stroke geared to the propeller shaft
• CAn exhaust-gas turbo-generator driven only by main engine exhaust
• DA steam turbo-generator supplied from the auxiliary boiler

In a turbocharged diesel, the turbocharger compressor's main function is to:

• AIncrease the mass of air delivered to the cylinders so more fuel can be burned
• BExtract exhaust heat to generate steam in the economizer
• CCool the charge air before it enters the scavenge manifold
• DDrive the camshaft that times fuel injection

Turbocharger compressor surge is best described as:

• AAn aerodynamic flow instability with violent pressure and flow reversals when the compres…
• BThe normal pressure pulsation felt in the manifold as the exhaust valves open in sequence
• COverspeeding of the turbocharger rotor caused by excessive exhaust gas temperature
• DRotor imbalance produced by deposits building up on the turbine blades

A scavenge fire in a two-stroke marine diesel is the burning of:

• AOil and carbon deposits accumulated in the scavenge air space and under-piston area
• BFuel leaking from a high-pressure pipe onto a hot exhaust manifold
• CLube oil vapor inside the crankcase after a bearing runs hot
• DSoot deposits igniting in the exhaust-gas economizer tube nest

Jacket-water cooling systems on marine diesels are chemically treated primarily to:

• AInhibit corrosion and scale formation in the engine water spaces
• BRaise the boiling point so the system can run at a lower pressure
• CIncrease the specific heat of the coolant so less flow is needed
• DNeutralize the acid formed by fuel sulfur on the cylinder liner running surface

Seawater flow through a diesel plant's central cooler is lost while the engine is on load. The first indication at the control station is most likely to be:

• ARising jacket-water and lube-oil temperatures
• BFalling scavenge air pressure with cooling temperatures unchanged
• CA low-level alarm on the jacket-water expansion tank
• DA rising crankcase oil level with normal running temperatures

The governor on a diesel generator set controls:

• AFuel rack position, to hold the set speed as electrical load changes
• BExcitation current, to hold the generator's terminal voltage
• CCharge air pressure, by regulating the turbocharger wastegate
• DCooling water flow, to hold jacket temperature at setpoint

On a controllable-pitch propeller (CPP) motor ship, ship speed and direction of thrust are normally changed by:

• AVarying propeller blade pitch while the engine holds a steady speed
• BReversing the main engine for each speed reduction
• CEngaging and disengaging the shaft-generator clutch
• DChanging the main reduction gear ratio while under way

An oil mist detector fitted to a large diesel crankcase warns of:

• AAn abnormally high oil mist concentration that can precede a crankcase explosion
• BWater contamination of the crankcase oil from a cracked liner
• CLoss of oil pressure at the main and crosshead bearings
• DExcessive cylinder oil feed reaching the scavenge space

The oil mist detector alarms high on a running main engine. The safest response is to:

• AReduce fuel, stop the engine per the casualty procedure, and leave the crankcase closed u…
• BStop the engine and open the crankcase doors at once to find the hot spot
• CHold sea speed and increase lube-oil cooler flow to cool the mist
• DSlow down and continue to the next port with the alarm accepted

Exhaust piping in the machinery space is lagged, and often water-jacketed, primarily to:

• AKeep hot surfaces from igniting leaking oil and from burning personnel
• BRaise exhaust gas velocity so the turbocharger produces more boost
• CPrevent soot from forming inside the exhaust manifold
• DHold exhaust gas above its dew point to stop uptake corrosion

An exhaust-gas economizer on a motor ship recovers main engine exhaust heat mainly to:

• ARaise steam for fuel heating, tank heating, and other service loads while the engine is r…
• BPreheat the scavenge air before it enters the cylinders
• CReduce exhaust gas temperature so the engine meets NOx Tier III limits
• DSuperheat the steam produced by the auxiliary oil-fired boiler

An indicator diagram taken from a diesel cylinder is used mainly to assess:

• ACompression and peak firing pressure, and how that unit's combustion compares with the ot…
• BTurbocharger compressor efficiency at part load
• CCrankshaft deflection and main bearing alignment
• DCylinder liner wear rate between overhauls

At steady load, one cylinder of a multi-cylinder diesel reads significantly higher exhaust temperature than the others. The most likely cause is:

• AOver-fueling or late injection on that unit
• BA fouled scavenge air cooler, which affects all cylinders
• CA fouled turbocharger turbine, which lowers boost across the engine
• DA cracked cylinder head admitting jacket water to that cylinder

The ideal Brayton cycle, on which a simple marine gas turbine is based, consists of:

• AAdiabatic compression, constant-pressure heat addition, adiabatic expansion, and constant…
• BAdiabatic compression, constant-volume heat addition, adiabatic expansion, and constant-v…
• CIsothermal compression, isentropic expansion, isothermal heat rejection, and isentropic c…
• DConstant-pressure evaporation, compression, constant-pressure condensation, and throttling

In a marine gas turbine with a free power turbine, the power turbine:

• ARuns on its own shaft, driven aerodynamically by gas from the gas generator, and drives t…
• BDrives the gas-generator compressor through a common shaft
• CProvides the starting torque that spins the gas generator up to light-off speed
• DRecovers exhaust heat downstream to raise steam in a waste-heat boiler

Surge in an axial gas-turbine compressor is normally guarded against by:

• AVariable inlet guide vanes and stator vanes together with interstage bleed valves
• BIncreasing fuel flow during acceleration to raise turbine inlet temperature quickly
• CReducing inlet filtration so the pressure loss ahead of the compressor is smaller
• DClosing the exhaust bypass to raise back pressure on the power turbine

Exhaust gas temperature (EGT) is a closely watched gas-turbine parameter because it:

• AIndicates hot-section gas temperature, which if exceeded shortens or destroys turbine bla…
• BShows when fuel supply pressure has dropped below the nozzle minimum
• CWarns that the inlet air filters are icing and restricting flow
• DConfirms that lube-oil supply temperature is within limits

A gas-turbine start in which EGT rises above the start limit shortly after light-off is called a:

• AHot start, which must be aborted and followed by a cool-down or motoring cycle
• BHot restart, which is a start attempted while the engine is still at operating temperature
• CHung start, in which the gas generator fails to accelerate past self-sustaining speed
• DWet start, in which fuel is admitted but ignition does not occur

Hot corrosion of gas-turbine hot-section components is accelerated by:

• ASea-salt ingestion combined with sulfur in the fuel, forming molten sulfate deposits on h…
• BProlonged operation at idle with low turbine inlet temperature
• CCompressor water washing carried out at the maker's recommended interval
• DUse of synthetic lubricating oil in the accessory gearbox

Air bled from a gas-turbine compressor is used for:

• AAnti-icing, cross-starting other units, seal pressurization, and similar pneumatic servic…
• BSupplying the combustion air delivered to the burner cans
• CCooling the lubricating oil in the oil cooler
• DProviding the motive medium for the compressor water-wash rig

A gas turbine is run at idle or motored for a period before final shutdown mainly to:

• ACool the rotor and casings evenly and avoid thermal distortion or rotor bow
• BPurge any unburned fuel remaining in the combustor and drains
• CRecharge the starting air receiver before the next start
• DLet the scavenge pumps empty the bearing sumps completely

A recuperator fitted to a gas-turbine plant improves thermal efficiency by:

• AUsing turbine exhaust heat to preheat compressor discharge air before it enters the combu…
• BCooling compressor discharge air between spools to reduce the work of compression
• CRaising steam from the turbine exhaust to drive a separate steam turbine
• DInjecting water into the compressor inlet to increase mass flow

Gas-turbine fuel systems use fine filtration and water coalescers because:

• AFuel nozzles and hot-section parts are quickly damaged by particulates and free water
• BFiltration raises the calorific value of the fuel before combustion
• CThe filters set the fuel pressure supplied to the nozzles
• DFiltration removes the sulfur that causes hot corrosion

Which fuel is involved in a Class A fire?

• AOrdinary combustibles such as wood, paper, cloth, and bedding
• BFlammable liquids such as fuel oil, lubricating oil, and solvents
• CEnergized electrical equipment such as switchboards and motors
• DCombustible metals such as magnesium and sodium

Before a fixed CO2 total-flooding system is released into a machinery space, the crew must:

• AAccount for all personnel, evacuate the space, and stop ventilation and close all openings
• BStart all machinery-space fans on high to clear smoke before release
• COpen the engine-room skylight to vent heat before discharging
• DBegin boundary cooling with the firemain before sounding the release alarm

Which practice satisfies the minimum requirement for entering an enclosed space such as a double-bottom tank?

• ATest the atmosphere for oxygen, flammable gas, and toxic gases, work under a signed entry…
• BVentilate for a fixed period and enter without testing if the fans have run overnight
• CEnter wearing self-contained breathing apparatus instead of testing the atmosphere
• DSend one person in briefly to look around while a second watches from the deck above

Under MARPOL Annex I, machinery-space bilge water discharged at sea through an oily-water separator must not exceed an oil content of:

• A15 ppm
• B100 ppm
• C5 ppm
• D1,000 ppm

Machinery-space bilge, sludge, and oily residue operations are recorded in the:

• AOil Record Book Part I
• BOil Record Book Part II, which covers cargo and ballast operations
• CGarbage Record Book required by MARPOL Annex V
• DEngine-room bell book kept by the watch engineer

When the oil content meter on an operating oily-water separator reads above 15 ppm, the installation is required to:

• AAutomatically stop the overboard discharge and divert the effluent back to a holding tank…
• BSound an alarm only, leaving the discharge decision to the watch engineer
• CAutomatically slow the feed pump until the reading falls below the limit
• DSwitch the sample line to clean seawater so the reading can be confirmed before stopping

Which practice belongs in a safe bunkering operation?

• AHold a pre-transfer conference, agree the plan and emergency stop signal, plug the scuppe…
• BTop the tanks to 100 percent so that a second transfer is not needed
• CRely on the barge's meter reading rather than gauging the receiving tanks
• DHold the maximum transfer rate until the final tank is nearly full

Free surface effect in a partly flooded compartment tends to:

• AReduce stability through a virtual rise of the center of gravity
• BIncrease GM, because the added water lowers the center of gravity
• CHave no effect until the compartment is more than half full
• DAffect trim only, leaving transverse stability unchanged

When dewatering a flooded machinery space with a portable submersible pump, the suction should be placed:

• AAt the lowest accessible point of the flooding, with the discharge safely led overboard
• BJust below the water surface so the pump does not pick up debris
• COn the fixed bilge main suction, using the ship's bilge pump instead of the portable unit
• DIn the engine-room sump tank so the water can be treated before it goes overboard

Lockout/tagout is applied before mechanical work on a pump in order to:

• AIsolate every energy source and stored energy so the machine cannot start or move unexpec…
• BRecord the machine's running hours before the overhaul begins
• CProvide the written record of the work for the next class survey
• DEnsure that the standby unit starts automatically while the pump is open

A Safety Data Sheet for a chemical used in the engine room provides:

• AHazard identification, first-aid measures, firefighting media, handling and storage, expo…
• BThe vessel's Inventory of Hazardous Materials used for ship recycling
• CThe supplier's certificate of analysis showing the purity of the delivered batch
• DThe Garbage Management Plan categories for disposing of the empty container