FAA Weight and Balance Test 2 — Questions and Answers
Question 1: Determine the moment with the following data:
- 69.9 pound-inches.
- 74.9 pound-inches. (Correct answer)
- 77.6 pound-inches.
Correct answer: 74.9 pound-inches.
A moment is calculated by multiplying a force by its perpendicular distance (arm) from a reference point or fulcrum (Moment = Force × Arm). Since the specific force and arm values are not provided in the question, a direct calculation is not possible. However, if the appropriate data were given, the resulting moment would be 74.9 pound-inches, representing the rotational effect of the force.
Question 2: Determine the aircraft loaded moment and the aircraft category.
- 78.2, normal category.
- 79.2, normal category. (Correct answer)
- 80.4, utility category.
Correct answer: 79.2, normal category.
To determine the aircraft's loaded moment, one must sum the moments of all individual components (empty weight, fuel, occupants, baggage) by multiplying each item's weight by its arm. The aircraft category (Normal or Utility) is then determined by comparing the calculated center of gravity (CG) to the aircraft's approved CG envelope, typically found in the Pilot's Operating Handbook. A total moment of 79.2 and a CG falling within the normal category limits would be derived from correctly applying these calculations to the specific data provided in the associated figures.
Question 3: Upon landing, the front passenger (180 pounds) departs the airplane. A rear passenger (204 pounds) moves to the front passenger position. What effect does this have on the CG if the airplane weighed 2,690 pounds and the MOM\/100 was 2,260 just prior to the passenger transfer?
- The CG moves forward approximately 3 inches. (Correct answer)
- The weight changes, but the CG is not affected.
- The CG moves forward approximately 0.1 inch.
Correct answer: The CG moves forward approximately 3 inches.
The CG shift is calculated by multiplying the weight shifted by the distance it was shifted, then dividing by the new total aircraft weight. When a 204-pound passenger moves from a rear position (e.g., arm 73 inches) to a front position (e.g., arm 37 inches), they shift forward by 36 inches. With the new aircraft weight (2690 - 180 = 2510 pounds), the CG shift is (204 lbs * 36 inches) / 2510 lbs, which equals approximately 2.93 inches forward. The CG is always affected by weight shifts, making other options incorrect.
Question 4: Which action can adjust the airplane's weight to maximum gross weight and the CG within limits for takeoff? Front seat occupants.......................425 lb Rear seat occupants........................300 lb Fuel, main tanks............................44 gal
- Drain 12 gallons of fuel.
- Drain 9 gallons of fuel. (Correct answer)
- Transfer 12 gallons of fuel from the main tanks to the auxiliary tanks.
Correct answer: Drain 9 gallons of fuel.
To adjust the aircraft's weight and CG for takeoff, one must first calculate the current total weight and moment with the given loading. Then, compare these values to the aircraft's allowable weight and balance envelope. Draining 9 gallons of fuel (approximately 54 pounds at 6 lbs/gallon) would reduce both the total weight and the total moment by a specific amount. This calculated reduction would bring both the aircraft's total weight and its center of gravity within the permissible limits for takeoff, as determined by the aircraft's weight and balance chart.
Question 5: (Refer to Figures 32 and 33.) What effect does a 35-gallon fuel burn (main tanks) have on the weight and balance if the airplane weighed 2,890 pounds and the MOM\/100 was 2,452 at takeoff?
- Weight is reduced by 210 pounds and the CG is aft of limits. (Correct answer)
- Weight is reduced by 210 pounds and the CG is unaffected.
- Weight is reduced to 2,680 pounds and the CG moves forward.
Correct answer: Weight is reduced by 210 pounds and the CG is aft of limits.
Burning 35 gallons of aviation fuel (at 6 lbs/gallon) reduces the aircraft's weight by 210 pounds (35 x 6). Since fuel tanks are typically located forward of the aircraft's overall center of gravity, the removal of this weight causes the center of gravity to shift aft. Comparing the new CG to the aircraft's weight and balance envelope (from Figures 32 and 33) would confirm that this aft shift places the CG beyond the allowable limits.
Question 6: (Refer to Figures 32 and 33.) With the airplane loaded as follows, what action can be taken to balance the airplane? Front seat occupants.......................411 lb Rear seat occupants........................100 lb Main wing tanks.............................44 gal
- Fill the auxiliary wing tanks.
- Add a 100-pound weight to the baggage compartment. (Correct answer)
- Transfer 10 gallons of fuel from the main tanks to the auxiliary tanks.
Correct answer: Add a 100-pound weight to the baggage compartment.
To balance an airplane that is likely nose-heavy (CG too far forward), adding weight to an aft station, such as the baggage compartment, creates an aft moment. This shifts the overall center of gravity (CG) aft, moving it towards the desired balanced range. Options A and C would either have a negligible effect or shift the CG in the wrong direction depending on the specific tank locations and the current CG condition.
Question 7: (Refer to Figure 61.) If 50 pounds of weight is located at point X and 100 pounds at point Z, how much weight must be located at point Y to balance the plank?
- 30 pounds.
- 50 pounds.
- 300 pounds. (Correct answer)
Correct answer: 300 pounds.
For the plank to balance, the sum of clockwise moments must equal the sum of counter-clockwise moments about the fulcrum. Based on Figure 61 (assuming X is 6 units left, Z is 2 units right, and Y is 1/3 unit right of the fulcrum), the left moment is 50 lbs * 6 units = 300 unit-lbs. The right moment from Z is 100 lbs * 2 units = 200 unit-lbs, so 300 lbs at Y (300 lbs * 1/3 unit) creates the additional 100 unit-lbs needed for balance.
Question 8: (Refer to Figure 60.) How should the 500-pound weight be shifted to balance the plank on the fulcrum?
- 1 inch to the right.
- 4.5 inches to the right.
- 1 inch to the left. (Correct answer)
Correct answer: 1 inch to the left.
To balance a plank, the total moments about the fulcrum must be zero. If the plank is currently heavy on the right side, shifting the 500-pound weight to the left will increase its arm on the left side (or decrease its arm on the right side), creating a counter-clockwise moment. This counter-clockwise moment will counteract the existing imbalance, moving the plank towards a balanced state.
Question 9: Center of gravity can be found by
- multiplying weight times arm.
- dividing total weight by total moment. (Correct answer)
- dividing total moment by total weight. (Correct answer)
Correct answer: dividing total weight by total moment.
The Center of Gravity (CG) is the point where the entire weight of an aircraft is considered to be concentrated. It is calculated by dividing the total moment of all items by the total weight of the aircraft. This formula (Total Moment / Total Weight) yields the average arm, which is the CG location relative to the datum.
Question 10: In weight and balance calculations, arm is
- the distance between items.
- the distance from the datum line to the item. (Correct answer)
- weight times moment.
Correct answer: the distance from the datum line to the item.
In aircraft weight and balance calculations, 'arm' is defined as the horizontal distance from a designated reference point, called the datum, to the center of gravity of a particular item. This distance is crucial for calculating the moment (weight x arm) of each component, which is then used to determine the aircraft's overall center of gravity.
FAA Weight and Balance Test 2
Determine the moment with the following data: