Question 17 OSE02 - Assistant Engineer - OSV

The Correct Answer is C **Why option C is correct:** The required oil injection rate for the vane-type air-starting motors is 3 drops of oil per cranking minute, and the current rate is only 1 drop per minute. This indicates that the lubricator is not delivering enough oil. The in-line lubricator uses a metering needle valve to control the flow rate of the lubricating oil into the airstream. To increase the flow rate (from 1 drop/min to the required 3 drops/min), the needle valve must be adjusted to allow more oil to pass through. Opening the needle valve (unscrewing or rotating it further away from the seat) will achieve this necessary increase in the oil injection rate. **Why the other options are incorrect:** * **A) The oil in the in-line lubricator should be replaced with oil of lower viscosity than specified.** While lower viscosity oil flows more easily, the problem statement explicitly notes that the current oil viscosity is *correct* (as specified). Using oil of lower viscosity could compromise the lubrication quality and potentially damage the air motor components, and it is a maintenance error to deviate from specified viscosity when a simple adjustment (C) is available to fix the flow rate. * **B) The starting air pressure supplied to the air-starting motors should be increased.** The problem states that the start air pressure is already "within the normal range." Air pressure primarily controls the torque and speed of the starter motor, not the flow rate of the oil from the lubricator (which is mechanically or pneumatically metered based on air flow but regulated by the needle valve). Increasing the air pressure beyond the normal range could damage the air motor seals or potentially lead to excessive speed, and it would not be the correct procedure for addressing low oil injection rate. * **D) The in-line lubricator oil injection metering needle valve should be further closed.** Closing the needle valve would restrict the oil flow even further, decreasing the injection rate below the current 1 drop per minute, moving the system further away from the required 3 drops per minute.