SPC Weight and Balance 1 — Questions and Answers
Question 1: What is the 'datum' used in aircraft weight and balance calculations?
- The point where the aircraft's weight is perfectly balanced
- An imaginary vertical plane from which all arm measurements are taken (Correct answer)
- The center of the aircraft's fuselage
- The point directly below the main landing gear
Correct answer: An imaginary vertical plane from which all arm measurements are taken
The datum is an imaginary vertical reference plane chosen by the manufacturer from which all horizontal distances (arms) are measured for weight and balance purposes.
Question 2: How is 'moment' calculated in weight and balance?
- Weight divided by arm
- Arm divided by weight
- Weight multiplied by arm (Correct answer)
- Weight added to arm
Correct answer: Weight multiplied by arm
Moment equals weight multiplied by arm (Moment = Weight × Arm), and it represents the turning force of that weight about the datum.
Question 3: What does an aircraft's 'empty weight' typically include?
- Airframe, engine, unusable fuel, and full engine oil (Correct answer)
- Airframe only, without any fluids
- Airframe, engine, and all usable fuel
- Airframe, passengers, and baggage
Correct answer: Airframe, engine, unusable fuel, and full engine oil
Standard empty weight includes the airframe, engines, all permanently installed equipment, unusable fuel, and full engine oil as specified in the POH.
Question 4: What is 'useful load'?
- The weight of fuel, passengers, and baggage only
- The maximum gross weight minus the basic empty weight (Correct answer)
- The weight of the aircraft minus engine oil
- The weight of payload minus fuel
Correct answer: The maximum gross weight minus the basic empty weight
Useful load is the difference between maximum allowable gross weight and the aircraft's basic empty weight, representing what the pilot can add (fuel, passengers, cargo).
Question 5: What happens to aircraft handling if the center of gravity (CG) is located too far forward?
- The aircraft becomes longitudinally unstable
- The aircraft tends to pitch up uncontrollably
- The aircraft becomes nose-heavy and requires excessive back pressure to rotate (Correct answer)
- Stall speed decreases significantly
Correct answer: The aircraft becomes nose-heavy and requires excessive back pressure to rotate
A forward CG makes the aircraft nose-heavy, requiring more elevator back pressure to maintain level flight and to rotate for takeoff, which can make rotation difficult.
Question 6: Where is the weight and balance data specific to your aircraft found?
- FAR/AIM
- Airport Facility Directory
- Pilot's Operating Handbook (POH) / Airplane Flight Manual (AFM) (Correct answer)
- Aeronautical Information Manual
Correct answer: Pilot's Operating Handbook (POH) / Airplane Flight Manual (AFM)
Aircraft-specific weight and balance data, including empty weight, CG location, and loading limits, is found in the Pilot's Operating Handbook or Airplane Flight Manual for that specific aircraft.
Question 7: What is the standard weight used for aviation gasoline (avgas) in weight and balance calculations?
- 5 pounds per gallon
- 6 pounds per gallon (Correct answer)
- 7 pounds per gallon
- 8 pounds per gallon
Correct answer: 6 pounds per gallon
Aviation gasoline (avgas) is standardly assumed to weigh 6 pounds per gallon for weight and balance calculations.
SPC Weight and Balance 1
What is the 'datum' used in aircraft weight and balance calculations?