Question 42 DDE01 - Designated Duty Engineer - Unlimited HP

The Correct Answer is B **Explanation for Option B (Correct Answer):** Option B is the correct and safest procedure because a safety shutdown triggered by high lubricating oil temperature indicates a critical failure mode (e.g., component friction, cooling system failure, pump failure, or insufficient oil flow) that risks severe mechanical damage. 1. **Cool Down Period:** A high-temperature shutdown means metal components (bearings, pistons, etc.) are thermally stressed. Attempting to immediately inspect hot components is dangerous and inaccurate (metal expansion distorts measurements). Allowing a significant cool-down period (like 2 hours, depending on engine size and ambient temperature) is essential to relieve thermal stress and prevent thermal shock upon restart. 2. **Inspection and Correction:** The engine must *not* be restarted until the root cause of the trip is identified and corrected. High oil temperature suggests imminent bearing damage or seizure. Inspection involves checking oil levels, filter condition, cooler performance, and potentially internal components. Restarting without correction guarantees a repeat shutdown and likely catastrophic failure. **Explanation for Incorrect Options:** **A) Allow the engine to cool off for two minutes, then restart and monitor the lubricating oil temperature to verify the cause of the shutdown.** * **Incorrect:** Two minutes is wholly insufficient time for a large diesel engine (like those used on a tug) to cool down meaningfully after a critical overheating event. Restarting after such a short period risks immediate repeat overheating, seizure, or catastrophic failure, as the underlying cause has not been investigated or corrected. **C) Immediately restart the engine, and monitor the oil temperature to verify the cause of the shutdown.** * **Incorrect:** This is extremely dangerous and violates standard safety procedures. Restarting an engine immediately after a high-temperature safety shutdown almost guarantees severe mechanical damage (such as wiping out bearings or piston seizure) because the cause (the lack of adequate cooling or lubrication) is still present. Safety shutdowns are protective; they are not diagnostic tools to be ignored. **D) Immediately perform the engine inspections to determine the cause of the high oil temperature safety shutdown.** * **Incorrect:** While inspection is necessary, performing inspections *immediately* is unsafe and impractical. Engine surfaces, piping, and oil can be extremely hot (hundreds of degrees), posing severe burn hazards to personnel. Components must be allowed to cool down sufficiently before handling and detailed inspection can safely commence.