The IDG DISC switchlight FAULT light illuminates under which conditions?

• A. High CSS oil temperature or Low oil pressure
• B. Low CSS oil temperature or High oil pressure
• C. High CSS oil temperature or High oil pressure
• D. Low CSS oil temperature or Low oil pressure

Answer: (A)

The IDG DISC switchlight FAULT is tied to the IDG’s oil-condition monitoring. It comes on whenever the oil is not within safe operating limits. Specifically, if the CSS oil temperature becomes too high or the oil pressure drops too low, the fault light illuminates. This serves to alert you to disconnect the IDG to prevent damage, since either condition means the generator isn’t being lubricated or cooled adequately.

Normal oil temperature and pressure would not trigger the light, and conditions like low temperature or high pressure aren’t fault signals for this indicator.