Question 3 UFIV01 - Chief Engineer - UFIV

The Correct Answer is D **Explanation for Option D (Correct):** The illustration MO-0122 typically depicts a large, slow-speed, two-stroke diesel engine (common for main propulsion on factory ships). A critical design feature of these engines is the "air box" (or scavenging air manifold) which surrounds the lower part of the cylinder liner. The air box is where compressed scavenging air enters the cylinder through ports cut into the liner wall (when the piston is near bottom dead center). To facilitate maintenance and inspection, these air boxes are equipped with removable covers known as "air box handhole covers." When the piston is correctly positioned (above the scavenging ports), removing these covers allows a direct visual inspection of the piston rings (both compression and oil control rings) via the liner's scavenging ports. This is the standard, practical, and non-invasive procedure for inspecting the rings in this type of engine. **Explanation of Incorrect Options:** * **A) The inspection takes place by removing the appropriate cylinder head valve cover and viewing through the resulting opening.** This is incorrect. The valve cover (or cylinder head inspection cover) allows access to the valve gear (rockers, springs, etc.) on the top of the cylinder. It does not provide any view down the cylinder wall to the piston rings, which are much further down. * **B) The inspection takes place by removing the appropriate oil pan cover and viewing through the resulting opening.** This is incorrect. The oil pan cover (or crankcase inspection door) provides access to the running gear (crankshaft, connecting rod bearings, crosshead). While it allows viewing the underside of the piston skirt and connecting rod, the piston rings are housed high up in the piston grooves and are obscured by the cylinder liner and piston structure from this angle. * **C) It is not possible to inspect the compression rings while in place inside the engine.** This is incorrect. As detailed in the explanation for D, visual inspection of the rings while the engine is assembled is entirely possible and standard procedure by using the air box handhole covers.