How does a 35-gallon fuel burn affect the weight and CG if the airplane weighed 2,890 pounds at takeoff?

After a 35-gallon fuel burn in an airplane that weighed 2,890 pounds at takeoff, the weight of the airplane decreases, as fuel is consumed and not replaced. Since aviation fuel weighs approximately 6 pounds per gallon, burning 35 gallons results in a weight reduction of about 210 pounds (35 gallons x 6 pounds/gallon = 210 pounds). Therefore, the new weight of the airplane would be 2,890 pounds - 210 pounds, resulting in a total weight of 2,680 pounds.

Regarding the center of gravity (CG), the fuel that is burned is typically located in the wings, so as this fuel burns, the weight decreases but the distribution of the remaining weight shifts. Depending on the aircraft design and its loading configuration, this can sometimes result in the CG moving aft, especially if there's a significant change in the distribution of weight.

In this context, while the weight has indeed decreased by 210 pounds, it's also crucial to note that the CG may be affected by that fuel burn, potentially leading to situations where it could be over the aft limits, especially if the remaining load is insufficiently forward. Therefore, while the weight is reduced, the condition of the CG needs careful consideration