Question 69 UFIV01 - Chief Engineer - UFIV

The Correct Answer is D **Explanation of why option D is correct:** Repairs to the fuel injection system or the governor directly affect how the engine is fueled and thus controlled. Any fault during reassembly or calibration can lead to the engine receiving too much fuel when started, resulting in an uncontrolled acceleration or "runaway" (overspeed). To stop a diesel engine that is running away, the fundamental requirement is to remove the source of power. Since a diesel engine uses compression ignition, the power source is the fuel and/or the air required for combustion. Therefore, making provisions to quickly shut off the **inlet air and/or the fuel supply** (e.g., via the emergency fuel rack shutoff or an emergency air intake damper) is the primary and most effective safety precaution taken before starting the engine under these circumstances. **Explanation of why the other options are incorrect:** * **A) Provisions should be made to shut off the engine's starting air supply to stop the engine in case there is an over speed on start-up.** * Once the engine starts and is running on its own power, the starting air supply is no longer used or needed. Shutting off the starting air will not affect an engine that is already running away due to excess fuel. * **B) Provisions should be made to shut off the engine's lubricating oil supply to stop the engine in case there is an over speed on start-up.** * Shutting off the lubricating oil supply will cause rapid engine damage and seizure over time, but it will not stop an engine that is actively overspeeding or running away in the critical moment. This action would create a catastrophic failure without immediately solving the overspeed problem. * **C) Provisions should be made to shut off the engine's control electrical power supply to stop the engine in case there is an over speed on start-up.** * While many large marine diesel engines rely on electrical power for ancillary controls (pumps, indicators), the core combustion process on most main propulsion diesel engines is mechanical (especially regarding the fuel rack position controlled by the governor). Simply removing the control power may inhibit future electronic control but might not immediately halt combustion or stop a mechanically controlled fuel injection system that is already stuck in the full-fuel position. The direct action required is physical deprivation of air or fuel.