How do you recover from a TRU fault while maintaining essential loads?

How do you recover from a TRU fault while maintaining essential loads?

• A. Replace TRU in air.
• B. Turn off all loads and wait.
• C. Use the remaining TRU or battery to energize essential DC buses, verify AC sources, and progressively re-energize nonessential loads.
• D. Assume shutdown of essential loads.

Answer: (C)

Maintaining essential loads is the priority when a TRU fault occurs. In this situation, you use the remaining TRU (or the battery) to keep the essential DC buses energized, which powers the critical aircraft systems you must have during flight. Once those essential buses are powered, you verify that the AC sources (like the engines or APU-driven generators) are healthy and able to support the system, then bring nonessential loads back online gradually. This approach preserves flight-critical functions while safely restoring other systems, avoiding sudden surges or overloads. Replacing the TRU in air isn’t an immediate, practical fix during flight. Turning off all loads and waiting would deprive essential systems of power and isn’t acceptable for safe operations. Assuming shutdown of essential loads would similarly leave you without the minimum power necessary to fly and navigate.

Maintaining essential loads is the priority when a TRU fault occurs. In this situation, you use the remaining TRU (or the battery) to keep the essential DC buses energized, which powers the critical aircraft systems you must have during flight. Once those essential buses are powered, you verify that the AC sources (like the engines or APU-driven generators) are healthy and able to support the system, then bring nonessential loads back online gradually. This approach preserves flight-critical functions while safely restoring other systems, avoiding sudden surges or overloads.

Replacing the TRU in air isn’t an immediate, practical fix during flight. Turning off all loads and waiting would deprive essential systems of power and isn’t acceptable for safe operations. Assuming shutdown of essential loads would similarly leave you without the minimum power necessary to fly and navigate.