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Your aircraft weighs 1530 pounds with no fuel. You add 49 litres of fuel, with a specific gravity of 0.72. What is the weight of the aircraft now?

  • A

    1608 pounds

  • B

    1598 pounds

  • C

    1638 pounds

  • D

    1565 pounds

Both kilograms and pounds are units of measurement of mass. The relationships between kilograms (kg) and pounds (lb) are:

  • 1 kg = 2.205 lb
  • 1 lb = 0.45 kg

1 litre of water = 1 kg

Fuel has a lower density than water and so 1 litre of fuel = less than 1 kg

We use the specific gravity to compare this lower density to water. 49 litres of fuel at a specific gravity of 0.72:

  • 49 x 0.72 = 35.28 kg of fuel
  • 35.28 kg x 2.205 = 77.79 (rounded up to 78) lbs of fuel
  • 1530 lbs + 78 lbs = 1608 lbs

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