Question 10 DDE01 - Designated Duty Engineer - Unlimited HP

The Correct Answer is D **Explanation for Option D (Correct Answer):** The problem states that the required oil injection rate is 3 drops of oil per cranking minute, but the observed rate is only 1 drop per minute. This indicates that the current flow rate of lubricant is insufficient. The in-line lubricator uses an oil injection metering needle valve to control the flow rate of the lubricant into the air stream supplying the starting motor. To increase the flow rate (the number of drops per minute), the metering needle valve must be adjusted to allow more oil to pass, which is achieved by **further opening** the valve. **Explanation of Incorrect Options:** * **A) The starting air pressure supplied to the air-starting motors should be increased.** Increasing the starting air pressure (which is already within the normal range) might slightly affect the lubricator function, but its primary purpose is to increase the torque/speed of the starting motor. It is not the correct or direct method for adjusting the oil injection rate of the lubricator. * **B) The in-line lubricator oil injection metering needle valve should be further closed.** Closing the metering needle valve would restrict the oil flow even further, decreasing the oil injection rate below the current 1 drop per minute. This would move the system further away from the required 3 drops per minute. * **C) The oil in the in-line lubricator should be replaced with oil of lower viscosity than specified.** The problem explicitly states that the oil viscosity is correct ("as specified"). Changing the oil viscosity would be a troubleshooting step only if the viscosity were suspected of being incorrect (e.g., too high). Since the viscosity is confirmed as correct, and the primary adjustment mechanism is the metering valve, changing the specified oil is unnecessary and incorrect.