10 exam-style questions with answers and explanations, straight from our 1,030-question bank. Tap an answer to check yourself. When you're ready, take the scored version in the free practice test.
After a mechanical fuel-injection pump is removed and reinstalled, one cylinder of a six-cylinder propulsion diesel develops a higher exhaust temperature. Its compression pressure remains normal, but the firing-pressure trace rises later and reaches a lower peak than before. The other cylinders are unchanged. Where should troubleshooting begin?
Correct answer: B - Retarded timing of the serviced injection pump
Two identical 500-kW diesel generators are operating in parallel with manual load sharing. No. 1 carries 410 kW and No. 2 carries 190 kW. Their reactive loads are equal, and bus voltage and frequency are normal. To equalize the real load while preserving the reactive-load balance, the engineer should:
Correct answer: D - Raise No. 2 governor demand and lower No. 1 governor demand gradually.
A refrigerated store is warming under an unchanged heat load, with normal evaporator airflow and no ice buildup. At the evaporator outlet, the measured pressure corresponds to a saturation temperature of -12°C, and the pipe temperature is -1°C. On the high side, the condensing saturation temperature is 38°C and the liquid-line temperature is 30°C. This plant's normal evaporator-outlet superheat is 4-7 K. Which interpretation explains the loss of refrigeration capacity?
Correct answer: A - 11 K superheat, consistent with evaporator starvation.
A machinery-space fire has resisted the initial attack. Everyone is outside the space and accounted for, the fuel shutoffs have been operated, and the ventilation fans are stopped. The fixed CO2 system is ready, but the machinery-space ventilation dampers remain open. What must be completed before the authorized release?
Correct answer: C - Close the dampers and the other openings required by the fire plan.
Opening a large steam user causes boiler drum pressure to fall. The gauge-glass level rises briefly, although steam mass flow exceeds feedwater mass flow and blowdown is unchanged. The level remains within its operating limits. The temporary rise should be understood as:
Correct answer: D - Drum swell raising the indicated level while the boiler loses water inventory.
A gas turbine lights off normally, but its gas-generator speed levels off at 42% and does not reach the maker's 55% self-sustaining speed within the permitted acceleration time. Flame indication remains steady, and exhaust temperature is 500°C against a 650°C start limit. Fuel is cut off and the prescribed motoring sequence begins. How should this event be entered in the machinery log?
Correct answer: A - Hung start
The main engine's duplex lubricating-oil filter differential pressure reaches 0.9 bar. The maker specifies changeover at 0.7 bar; the bypass opens at 1.2 bar. Oil temperature, downstream oil pressure, and bearing temperatures remain normal. The clean standby chamber has been filled and vented, and the filter is designed for changeover under load. What is the appropriate operating response?
Correct answer: C - Change over to the clean chamber and verify downstream oil pressure.
A fully primed centrifugal pump draws from a vented tank through a leak-tight suction line. As the tank level falls, a gravel-like noise develops and discharge pressure fluctuates. The suction inlet remains submerged. Reducing flow with the discharge valve, within the pump's approved operating range, quiets the pump. Taken together, these observations point to:
Correct answer: B - Cavitation from insufficient available net positive suction head
A pressure transmitter is calibrated for 2.0-10.0 bar with a linear 4-20 mA output. During a fault check, an independent calibrated gauge reads 6.0 bar and the loop current measured at the display input is 12.0 mA, but the display reads 5.0 bar. The discrepancy is most consistent with an error in the:
Correct answer: A - Display input's engineering-unit scaling
While machinery-space bilge water is being discharged in U.S. navigable waters, the oil-content monitor reads 8 ppm. An observer confirms that an oil sheen is forming directly from the vessel's discharge. The separator and its alarm are operating. Which instruction governs this situation?
Correct answer: D - Stop discharging overboard; retain the mixture for lawful disposal.
The National Assistant Engineer (Limited) Steam/Motor/GT (USCG-AE-LTD) exam is organized into 1 knowledge domains. These free practice questions are drawn from across them so you can see where you're strong and where to study:
The full bank has 1,020 more USCG-AE-LTD questions with explanations.
Continue in the free practice test →
View plans