FAA AMT Airframe Practice Exam 2026 – All-in-One Study Guide to Master Aviation Maintenance Technician Certification!

The correct answer is C. In an EFIS (Electronic Flight Instrument System), the symbol generator (SG) plays a crucial role in the system. Its function is to receive and process input signals from various aircraft and engine sensors, such as airspeed sensors, altitude sensors, engine sensors, etc. These input signals are then converted into meaningful data that can be displayed on the EFIS screens for the pilot. Essentially, the symbol generator acts as an interface between the sensors on the aircraft and the displays in the cockpit, ensuring that accurate and relevant information is presented to the flight crew in real-time.

Option A is incorrect because while the symbol generator does play a role in displaying data, its primary function is to process and format the data for display rather than directly displaying it.

Option B is incorrect because controlling flight data entry is not the main function of the symbol generator. Flight data entry is typically performed through other systems or interfaces in the cockpit.

Option D is incorrect because the symbol generator is not designed to act as a backup power source. Backup power sources are usually provided by separate systems in the aircraft to ensure redundancy in critical systems during emergencies.