Question 2 CEL01 - Chief Engineer - Limited

The Correct Answer is A ### Explanation for Option A (Correct) **A) the system has been drained and then filled with new oil** Purging (bleeding) air is essential whenever a significant amount of air is introduced into the hydraulic circuit. When a hydraulic system is drained for maintenance or fluid replacement, air replaces the oil in the lines, components, actuators, and the pump casing. When the system is refilled, this trapped air becomes suspended or pocketed within the fluid and components. Because air is highly compressible, operating the system without purging will result in spongy operation, erratic movement, noise, excessive heat, and potential damage (like cavitation) to the pump. Therefore, after a major fluid change or system service, purging the system is a mandatory step. --- ### Explanation for Incorrect Options **B) adding small amounts of oil to the system** Adding small amounts of oil to top off the reservoir (as long as the level never dropped low enough to starve the pump inlet) typically does not introduce air into the operational lines or components. Purging is not necessary for routine minor oil additions. **C) the system has been idle for a long period of time** While long-term idleness may cause some minor fluid seepage past seals or contraction of elastomers, it does not inherently introduce significant volumes of air into the operational hydraulic lines, provided the system was closed and properly sealed when it was shut down. **D) the system has been overheated** Overheating is a thermal issue that causes fluid breakdown, seal degradation, and potentially fluid vaporization. While overheating is damaging and may require subsequent maintenance (like fluid replacement, which *would* require purging), the act of overheating itself does not introduce external air into the system lines.