What is cross feed system?

• A. Twin engine aircraft incorporate this to feed one engine from both fuel tanks (engine failure)
• B. A system to balance fuel across wings
• C. A system to vent vapors
• D. A system to heat fuel

Answer: (A)

Cross feed is a fuel system capability that lets fuel be transferred between tanks and delivered to any engine from either tank. In a twin-engine setup, each engine is normally fed from its own tank, but if a pump or feed line on one side fails or you need to draw from the other tank to keep an engine supplied, the crossfeed valve can be opened. This ensures continuous engine operation and provides flexibility for balancing fuel between wings as consumption changes. It’s not about venting vapors or heating fuel, and its primary purpose is routing fuel between tanks to prevent an engine from losing feed and to aid fuel balance when needed.