What is the purpose of a crossfeed valve in a twin-engine installation?

• A. To allow fuel transfer between left and right wing tanks to balance tanks or supply a pump when one pump is inoperative.
• B. To vent fuel across tanks.
• C. To regulate fuel temperature.
• D. To replace the engine-driven pump.

Answer: (A)

In a twin-engine fuel system, the crossfeed valve creates a pathway between the left and right wing fuel tanks so fuel can be transferred from one side to the other and to the engines as needed. This flexibility lets you keep both engines fed if one pump or feed line is inoperative, and it helps maintain fuel balance as tanks empty at different rates. If the left wing pump fails, the crossfeed can supply the left engine from the right-wing fuel, preventing an engine cutoff. It’s not about venting fuel, nor about regulating temperature, and it doesn’t replace the engine-driven pump—it's an alternate route to keep fuel flowing when needed.