What is the maximum fuel imbalance allowed?

• A. 100 lbs
• B. 178 lbs
• C. 210 lbs
• D. 267 lbs

Answer: (B)

Fuel imbalance between the left and right wing tanks affects where the aircraft’s center of gravity sits. If one side is heavier, the CG shifts and the airplane can become harder to control in certain phases of flight or outside the approved weight-and-balance envelope. The system is designed with a specific allowable imbalance so you can still fly safely while ensuring the CG stays within certified limits and the fuel system can still feed the engine reliably (using crossfeed if needed).

For the PC-12 NGX, that published limit is 178 pounds between the left and right wing tanks. Keeping the imbalance at or below this value helps maintain the proper CG range from takeoff through landing and prevents fuel-feed issues, which is why this is the correct maximum. It also corresponds to roughly 26 gallons of Jet A, helping you visualize the amount of fuel difference allowed.

If the imbalance approaches the limit, you balance by transferring fuel or selecting the other tank to ensure you stay within the allowable range.