Question 42 DDE04 - Designated Duty Engineer - 1000-4000 HP

The Correct Answer is D **Explanation for Option D (Correct Answer):** Pressure-compensated governors, such as those used on marine propulsion diesels, often incorporate safety features integrated into their design or accessories. When fitted with a connection for the engine's main lube oil pressure line, this connection serves a critical safety function related to the engine's health. 1. **Alarm Activation:** The pressure line feeds into a sensing mechanism (often a switch or transducer) within the governor system or its associated panel. If the engine lube oil pressure drops below a safe operational threshold, this mechanism is designed to immediately trigger a low-pressure alarm, alerting the crew. 2. **Engine Shutdown (Safety Function):** Crucially, the system is also designed to initiate an automatic engine shutdown if the lube oil pressure continues to fall to a dangerously low level (a level that indicates catastrophic failure or imminent damage). This function is vital because running a diesel engine without adequate lubrication rapidly leads to severe internal damage. The governor system uses the pressure signal to physically pull the fuel rack to the zero-fuel position, stopping the engine. Therefore, the lube oil pressure connection provides the input signal necessary for both activating a low-pressure alarm and executing a protective engine shutdown. **Explanation of Incorrect Options:** **A) It is used as a governor lubricant and as a hydraulic power medium for the power cylinder.** * **Incorrect:** While some governors use engine lube oil for sensing pressure, the main hydraulic power medium for most modern, pressure-compensated governors (like those manufactured by Woodward) is *their own self-contained oil supply* (often referred to as governor oil), which is separate from the engine's main lubricating oil system. The engine lube oil connection is purely for sensing/safety, not for primary lubrication or hydraulic power transmission within the governor itself. **B) It is used solely for the purpose of achieving engine shutdown on low engine lube oil pressure.** * **Incorrect:** While engine shutdown is a primary goal, modern safety systems are typically designed for two tiers of protection: warning (alarm) first, and then immediate action (shutdown). Saying it is used *solely* for shutdown ignores the integrated alarm function that precedes the shutdown. **C) It is used solely for the purpose of activating an alarm on low engine lube oil pressure.** * **Incorrect:** This option is inadequate. While activating an alarm is a function, stopping the engine under dangerously low pressure is the ultimate protection provided by the safety system. Relying only on an alarm could lead to catastrophic engine failure if the crew does not react instantly.