GoJet Airlines CRJ-550 Practice Test 2026 – Comprehensive Exam Prep

The main idea is that the DC Emergency Bus stays alive to power essential safety systems when normal power is lost. In this aircraft, the engine fire extinguishers rely on that bus to discharge. When you command an engine fire extinguishing action, the squibs that release the extinguishing agent are energized by power from the DC Emergency Bus, allowing immediate deployment even with the main electrical system out. The other items listed—APU fire extinguisher, Fuel SOV, and Hydraulic SOV—aren’t powered by the DC Emergency Bus in the listed source, so they aren’t the devices kept alive by that bus in an electrical emergency.