SPC Weight and Balance 2 — Questions and Answers
Question 1: What is the 'center of gravity' (CG) of an aircraft?
- The point through which the total weight of the aircraft acts vertically downward (Correct answer)
- The geometric center of the fuselage
- The midpoint between the nose and tail
- The point directly above the main landing gear
Correct answer: The point through which the total weight of the aircraft acts vertically downward
The CG is the theoretical point through which the entire weight of the aircraft is considered to act, and it must remain within prescribed limits for safe flight.
Question 2: What effect does exceeding the maximum gross weight have on an aircraft's stall speed?
- Stall speed decreases
- Stall speed remains unchanged
- Stall speed increases (Correct answer)
- Stall speed is not affected by weight
Correct answer: Stall speed increases
Operating above maximum gross weight increases stall speed because the wings must generate more lift, requiring a higher angle of attack before stalling.
Question 3: A pilot calculates the total moment for a loaded aircraft. The next step to find the actual CG location is to:
- Multiply total moment by total weight
- Divide total moment by total weight (Correct answer)
- Subtract total weight from total moment
- Add total weight to total moment
Correct answer: Divide total moment by total weight
CG location (in inches from datum) is found by dividing total moment by total weight, giving the distance from the datum to the balance point.
Question 4: What is a 'moment envelope' (CG envelope) used for in weight and balance?
- Calculating fuel burn rates during flight
- Determining approved CG range at various aircraft weights (Correct answer)
- Establishing maximum takeoff distances
- Recording aircraft maintenance history
Correct answer: Determining approved CG range at various aircraft weights
The moment envelope (or CG envelope) is a graph in the POH that shows the acceptable range of CG positions at various weights, allowing pilots to verify the aircraft is safely loaded.
Question 5: Which of the following is generally NOT included when calculating an aircraft's useful load?
- Pilot and passengers
- Usable fuel
- Baggage
- Permanently installed avionics (Correct answer)
Correct answer: Permanently installed avionics
Permanently installed avionics are part of the basic empty weight, not useful load; useful load consists of items the pilot adds, such as occupants, baggage, and usable fuel.
Question 6: As fuel is consumed during flight, how might the aircraft's CG change?
- CG always moves forward as fuel burns
- CG always moves aft as fuel burns
- CG movement depends on where the fuel tanks are located relative to the CG (Correct answer)
- CG does not change as fuel burns
Correct answer: CG movement depends on where the fuel tanks are located relative to the CG
The direction CG shifts as fuel burns depends on the tank location relative to the current CG; if fuel tanks are aft of CG, burning fuel moves CG forward, and vice versa.
Question 7: What is 'tare weight' in the context of aircraft weight and balance?
- The weight of passengers and baggage
- The weight of unusable fuel
- The weight of equipment such as chocks or blocks that is placed on the scales during weighing but is not part of the aircraft (Correct answer)
- The maximum allowable takeoff weight
Correct answer: The weight of equipment such as chocks or blocks that is placed on the scales during weighing but is not part of the aircraft
Tare weight is the weight of any items (chocks, wheel blocks, fire extinguishers) placed on the scales during official weighing that must be subtracted to get the true aircraft weight.
SPC Weight and Balance 2
What is the 'center of gravity' (CG) of an aircraft?