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Q1. Describe, with the aid of an S/N curve, the relationship between applied stress and the number of applied stress fluctuations in fatigue crack propagation. (5)

Define the term Stress Raiser, giving examples and explaining the influence of a stress raiser on the propagation of a crack. (5)

Define the term Fatigue Limit, explaining, with examples, how poor maintenance and poor machine operation can result in fatigue crack propagation even though a component has been designed to avoid fatigue cracking (6)

Q2. As Chief Engineer write instructions for the main and auxiliary engine fuel change-over procedures to be followed when a vessel is due to move into an Emission Control Area. Approximate times must be mentioned to ensure that the vessel does not infringe any regulations and the instructions must mention steps required to avoid cross-contamination of fuel in service tanks, where MGO is carried as the low sulphur fuel. (16)

Q9. Explain why multiple air inlet and exhaust valves are fitted to some medium speed diesel engines.(4)

Explain how the valve actuator (tappet) clearance is set for multiple valve installations. (4)

Write a procedure for checking the valve operating mechanisms of a medium speed engine. (8)

Q5. Write a report for the engineering superintendent regarding the replacement of the fuel injectors of three main engine units due to severe erosion of the nozzle holes and burning of the injector tips. The report must explain how the defects were detected, the likely cause of the damage and the action which has been instituted to prevent further incidents of this type. (16)

Q4. With reference to medium speed diesel engine cylinder liners:

a. Explain the cause and effects of polishing and glazing; (6)

b. Explain the action of an anti-polishing ring during the operation of the engine; (5)

c. Describe how effective cylinder lubrication is achieved. (5)

Q6. Write instructions for the actions to be taken by a duty engineer following activation of a slow speed main engine exhaust gas differential temperature alarm during a period of unmanned machinery operation. The instructions must cover the period from activation of the alarm to return of the main engine to normal operation. (16)

Q6. A. Describe how crosshead bearing and guide clearances can be checked. (6)

b. Describe, with the aid of a sketch, the procedure for checking the condition of a crosshead engine bottom end bearing. (10)

Q9. With reference to boilers and steam generation systems:

(a) Explain the term water hammer, stating how it is caused and describing the possible consequences of it; (4)

(b) explain how water hammer can be avoided; (4)

(c) describe, with the aid of a sketch, how the boiler fuel system may be operated in port to comply with local emission control regulations. (8)

Q9. A. Describe, with the aid of a sketch, a system for burning gaseous fuel in a two-stroke diesel engine, indicating safety features fitted and explaining why the gas has to be injected into the cylinder rather than mixed with the combustion air outside of the cylinders. (12)

B. Define the term Methane Slip, explaining how it occurs and why it is undesirable. (4)