Where is the red disc that indicates the APU bottle has not been discharged located?

Where is the red disc that indicates the APU bottle has not been discharged located?

• A. On the aft fuselage, just below the right horizontal stabilizer
• B. On the nose
• C. In the cockpit
• D. In the main cabin

Answer: (A)

The red disc is an exterior visual indicator for the APU fire bottle status. It’s placed on the aft fuselage, just below the right horizontal stabilizer, so crew or maintenance can quickly confirm whether the APU bottle has discharged without opening any panels. If the bottle has not discharged, the red disc is visible; after discharge, the indicator changes from red to not showing that status. The nose, cockpit, and main cabin locations are not used for this purpose, since the APU and its fire-suppression components are in the tail area and require an exterior indicator for a quick, unobstructed check.

The red disc is an exterior visual indicator for the APU fire bottle status. It’s placed on the aft fuselage, just below the right horizontal stabilizer, so crew or maintenance can quickly confirm whether the APU bottle has discharged without opening any panels. If the bottle has not discharged, the red disc is visible; after discharge, the indicator changes from red to not showing that status. The nose, cockpit, and main cabin locations are not used for this purpose, since the APU and its fire-suppression components are in the tail area and require an exterior indicator for a quick, unobstructed check.