PPL PPL Weight and Balance 1 — Questions and Answers
Question 1: What is the standard weight of aviation fuel (100LL) per US gallon used in weight and balance calculations?
- 6.0 pounds (Correct answer)
- 6.7 pounds
- 7.5 pounds
- 8.33 pounds
Correct answer: 6.0 pounds
Aviation gasoline (100LL) weighs 6.0 pounds per gallon at standard temperature, which is the value used in standard weight and balance calculations.
Question 2: In weight and balance, what is the 'datum'?
- The total weight of all items loaded in the aircraft
- An imaginary vertical reference plane from which all arm measurements are taken (Correct answer)
- The point at which the aircraft physically balances when suspended
- The maximum weight the aircraft structure can safely carry
Correct answer: An imaginary vertical reference plane from which all arm measurements are taken
The datum is an imaginary vertical plane selected by the manufacturer from which all horizontal distances (arms) are measured for weight and balance purposes.
Question 3: What is a 'moment' in weight and balance calculations?
- The weight of an object multiplied by its arm (distance from datum) (Correct answer)
- The total weight of the aircraft at takeoff
- The distance from the datum to the center of gravity
- The maximum load that can be placed at a given station
Correct answer: The weight of an object multiplied by its arm (distance from datum)
A moment is the product of a weight and its arm (distance from the datum), expressed in pound-inches, and represents the turning force that weight exerts about the datum.
Question 4: What effect does an aft (rearward) center of gravity beyond limits have on longitudinal stability?
- Increases pitch stability and makes stall recovery easier
- Decreases longitudinal stability and can make recovery from a stall difficult or impossible (Correct answer)
- Has no significant effect on aircraft stability
- Increases the aircraft's stall speed
Correct answer: Decreases longitudinal stability and can make recovery from a stall difficult or impossible
An aft CG beyond the approved limit reduces longitudinal stability, making the aircraft pitch-sensitive and potentially unrecoverable from a stall or spin.
Question 5: 'Useful load' is defined as the difference between which two weights?
- Maximum gross weight and basic empty weight (Correct answer)
- Maximum ramp weight and maximum takeoff weight
- Zero fuel weight and maximum landing weight
- Operating empty weight and payload weight
Correct answer: Maximum gross weight and basic empty weight
Useful load equals maximum gross weight minus basic empty weight, representing the total weight available for fuel, oil (if not included in empty weight), passengers, baggage, and cargo.
Question 6: A forward CG condition beyond limits primarily causes which problem?
- Insufficient elevator authority to raise the nose for landing flare (Correct answer)
- Increased lateral stability and improved roll control
- Higher cruise speeds due to reduced induced drag
- Improved spin recovery characteristics
Correct answer: Insufficient elevator authority to raise the nose for landing flare
An excessively forward CG requires full up-elevator to flare for landing; beyond the forward limit, the pilot may not have enough elevator authority to arrest the descent rate.
Question 7: Which document specifies the approved CG limits and weight and balance data for a specific aircraft?
- The Aeronautical Information Manual (AIM)
- The Pilot's Operating Handbook (POH) / Airplane Flight Manual (AFM) (Correct answer)
- The Airport/Facility Directory (Chart Supplement)
- FAR Part 91
Correct answer: The Pilot's Operating Handbook (POH) / Airplane Flight Manual (AFM)
The Pilot's Operating Handbook (POH) or Airplane Flight Manual (AFM) contains the aircraft-specific weight and balance data, loading graphs, and approved CG envelope.
PPL PPL Weight and Balance 1
What is the standard weight of aviation fuel (100LL) per US gallon used in weight and balance calculations?