WorksheetsPASGT LEC SEMIFINAL QUIZ 2
Total questions: 20
Worksheet time: 15mins
You are tasked with designing a shutdown checklist for a new marine gas turbine model. Which elements are essential to include for maximum safety?
Immediate fuel cut-off, rapid rotor stop, auxiliary system shutdown, and skipping post-checks to shorten downtime despite potential safety compromises
Increasing turbine speed before shutdown to enhance airflow circulation, assuming that higher momentum will assist natural cooling
Gradual load reduction, fuel cut-off, cool-down monitoring, auxiliary system sequencing, post-shutdown inspections
Only recording TIT and EGT readings while ignoring lubrication system status or cooling behavior, assuming mechanical systems will remain unaffected
To minimize the risk of thermal shock during shutdown, which strategy would you recommend in your procedural design?
Shut down lubrication pumps before temperature stabilization to prevent oil degradation, even if bearings remain hot
Implement a staged load reduction protocol with monitored temperature limits to ensure controlled cooling and component integrity
Cut fuel supply abruptly to speed up cooling without accounting for thermal stress on turbine blades
Close all intake and exhaust doors immediately at idle to minimize air circulation and reduce heat transfer, despite possible residual heat buildup
You are creating a post-shutdown maintenance schedule. Which approach best ensures turbine longevity?
Delay inspection until the next operational cycle to minimize manpower requirements, even if minor issues go undetected
Include visual inspections, oil sampling, vibration analysis, FOD checks, and event log review to identify wear patterns and potential faults early
Skip oil checks if turbine appears mechanically sound, assuming that visible inspection is sufficient for maintenance decisions
Only inspect bearings without reviewing operational logs, focusing on mechanical components but neglecting recorded performance anomalies
A new turbine design requires an improved FOD prevention system. Which design feature would you incorporate?
Enhanced intake screens, routine FOD walk-downs, and intake/exhaust sealing procedures to ensure a controlled and debris-free environment
Ignoring intake inspection since modern turbines are robust and designed to tolerate minor debris ingestion without failure
Increasing turbine idle speed to blow debris away, relying solely on airflow velocity instead of proactive FOD control measures
Smaller intake openings to limit airflow entry, assuming this will reduce debris without significantly affecting performance
To design a safer emergency shutdown sequence, which combination of measures should be included?
Rapid fuel cut-off with no monitoring of temperature or vibration, prioritizing speed of shutdown over mechanical safety
Immediate shutdown of all systems including lubrication, assuming thermal inertia will not affect critical components
Immediate E-stop activation, fuel isolation, continued lubrication/cooling, fire suppression readiness, post-trip inspection for damage assessment
Delayed E-stop until rotor stops naturally, then isolate fuel to minimize fuel waste, even if shutdown timing is less controlled
During a start-up sequence, the oil pressure is below the recommended minimum, but the turbine is scheduled for immediate departure. What is the safest decision?
Start the turbine and shut it down if pressure drops further during normal operation
Continue the start-up sequence and monitor oil pressure closely during acceleration
Delay departure and investigate the lubrication system for possible pump or sensor issues before risking mechanical damage
Bypass the low-pressure alarm and proceed to avoid operational delays regardless of risk
The EGT is rising steadily but remains within acceptable limits. Which course of action is most appropriate?
Gradually reduce load and assess possible causes such as compressor fouling or air path restriction
Ignore the increase since it is still below the operational limit and turbine output remains stable
Shut down the turbine immediately to prevent overtemperature even though no alarm is triggered
Open the air intake fully to reduce exhaust temperature quickly regardless of efficiency impact
During operation, vibration levels are stable but oil pressure suddenly drops. What should the operator prioritize?
Adjust the fuel-air ratio to increase oil temperature and restore pressure
Ignore the drop if no alarms are triggered by the control system and continue running
Maintain current power output to stabilize pressure through system inertia
Immediately reduce load and investigate lubrication system functionality to avoid bearing damage
A turbine trips automatically due to overspeed, but no mechanical damage is reported. What is the most appropriate next step?
Reset the system immediately and attempt a restart without inspection
Ignore the incident and resume operation with reduced load immediately
Bypass the speed governor to avoid future automatic shutdowns even if risk increases
Conduct a thorough investigation of the speed governor and trip system before restarting the turbine
After a successful emergency shutdown, the turbine casing temperature remains unusually high. What should be done?
Begin maintenance while the casing is still hot to reduce downtime
Continue cooling airflow and monitor temperatures before any restart or further action
Restart the turbine to improve airflow cooling regardless of trip history
Ignore temperature readings if the turbine is no longer running and prepare for next start
A gas turbine experiences a sudden rise in vibration and EGT simultaneously. Which is the most likely cause?
Malfunction in the fuel control system causing uneven combustion without mechanical imbalance
Rotor imbalance or possible foreign object ingestion disturbing both flow and thermal stability
Partial failure of the cooling system leading to localized temperature spikes but no vibration
Incorrect air-fuel ratio settings causing incomplete combustion and minor temperature fluctuations
If the turbine fails to reach self-sustaining speed during startup, which component is most likely malfunctioning?
Starting motor or auxiliary power unit not delivering sufficient torque for acceleration
Exhaust diffuser geometry causing poor pressure recovery at startup conditions
Lubrication oil cooler creating drag due to excessive viscosity in the bearing system
A turbine trips automatically without operator input. What is the most probable cause?
Manual emergency stop activation initiated by remote control panel
Automatic protective logic detected a parameter exceeding safety thresholds
Lubrication oil filter becoming partially clogged but still within limits
Fuel valve manually closed by engineering staff during load reduction
During a shutdown, rapid cooling leads to rotor bowing. Which procedure was likely skipped?
Load ramping to reduce thermal gradients before shutdown
Controlled rundown period to allow gradual temperature equalization
Sealing air pressurization to minimize leakage during cooling
Compressor washing sequence to prevent thermal distortion during shutdown
A gradual increase in EGT over time during normal operation usually indicates:
Fuel pump failure occurring suddenly with no change in airflow dynamics
Combustor instability due to fluctuating ignition quality rather than compressor issues
Compressor fouling or reduced airflow efficiency leading to hotter combustion temperatures
Overspeed condition caused by governor malfunction unrelated to temperature rise
If the turbine fails to reach self-sustaining speed during startup, which component is most likely malfunctioning?
Starting motor or auxiliary power unit not delivering sufficient torque for acceleration
Exhaust diffuser geometry causing poor pressure recovery at startup conditions
Lubrication oil cooler creating drag due to excessive viscosity in the bearing system
Sealing air system over-pressurizing and restricting compressor rotational speed
A gas turbine experiences a sudden rise in vibration and EGT simultaneously. Which is the most likely cause?
Malfunction in the fuel control system causing uneven combustion without mechanical imbalance
Rotor imbalance or possible foreign object ingestion disturbing both flow and thermal stability
Partial failure of the cooling system leading to localized temperature spikes but no vibration
Incorrect air-fuel ratio settings causing incomplete combustion and minor temperature fluctuations
After a successful emergency shutdown, the turbine casing temperature remains unusually high. What should be done?
Begin maintenance while the casing is still hot to reduce downtime
Continue cooling airflow and monitor temperatures before any restart or further action
Restart the turbine to improve airflow cooling regardless of trip history
Ignore temperature readings if the turbine is no longer running and prepare for next start
A turbine trips due to overspeed during acceleration. Which corrective action should take highest priority before restart?
Reset the control panel alarms and restart immediately
Inspect and recalibrate the governor or fuel control system
Purge the combustion chamber and continue operation to eliminate residual fuel in the combustion chamber
Increase oil pressure to stabilize rotor speed
Which action is the most appropriate if the turbine shows a gradual increase in EGT but fuel pressure and vibration remain stable?
Continue operation and ignore the reading because this is a part of normal start-up of the engine
Isolate the fuel system immediately without inspection
Increase turbine load to reduce temperature fluctuations
Schedule a shutdown and inspect the cooling system
