FAA Powerplant Written Practice Test

What marking tool should not be used on turbine engine components exposed to high temperatures?

1. Permanent marker

2. Wax or grease pencil

3. Graphite lead pencil

4. Non-toxic paint

The correct answer is: Wax or grease pencil

Using a wax or grease pencil on turbine engine components exposed to high temperatures is incorrect because these materials can melt or degrade under extreme conditions. High temperatures typical of turbine engines can cause the wax or grease to transfer to the component surfaces, potentially compromising the integrity of the parts and causing adverse operational effects. In contrast, permanent markers and non-toxic paints can be formulated to withstand higher temperatures without degrading. Similarly, a graphite lead pencil produces markings that are more stable under heat conditions. Understanding the materials and their reactions to the high-temperature environments in turbine engines is crucial for maintaining the reliability and safety of the engine system.