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7 Answers

Unusable fuel in weight and balance computations

Asked by: 2182 views General Aviation

I've weighed my airplane without fuel and of course with unusable fuel. Do I have to add the unusable fuel into my weight and balance form when computing BOW?

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7 Answers



  1. Kris Kortokrax on Jul 10, 2019

    The glossary in the Aviation Maintenance Technician Handbook states that “Standard Empty Weight” includes unusable fuel. “Basic Empty Weight” is Standard Empty Weight plus optional equipment.

    Basic Operating Weight would be Basic Empty Weight plus required crew, their baggage and other standard items such as potable water, meals, etc.

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  2. AMT 73 on Jul 10, 2019

    Okay I understand BOW. But is there any case where you would add unusable fuel to the empty weight? I assume the only time you would do that would be the first weighing where there is literally no fuel in the aircraft at all and you need to add the TCDS posted unusable fuel weight and location. Is that correct?

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  3. Kris Kortokrax on Jul 10, 2019

    It is not that you add unuseable fuel to the empty weight, the empty weight includes unuseable fuel. The way you would go about it (I think) would be to level the aircraft and then drain fuel until nothing comes out. What remains would be unuseable fuel and would be included in the numbers that show up on the scales.

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  4. AMT 73 on Jul 10, 2019

    Yes but the TCDS lists unusable fuel for all aircraft. If you were weighing the aircraft for the first time before it was fueled wouldn’t you have to then add the TCDS posted unusable fuel and location to the empty weight form because the unusable fuel is part of the empty weight? I know I’ve seen unusable fuel added to weight and balance forms before and I don’t know why it would be added if the aircraft was already weighed with unusable fuel. The only reason I can see is this was the first weighing, even before it was fueled for the first time.

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  5. Kris Kortokrax on Jul 10, 2019

    I’m not sure how we got from you weighing your airplane to weighing a new airplane for the first time.

    I believe that manufacturers do not weigh every aircraft that comes out of the factory, but use standard weights based on equipment installed and actually weigh a fraction of the aircraft coming down the production line.

    The procedures for weighing an aircraft are outlined in the Aviation Maintenance Technician Handbook FAA-H-8083-30, Chapter 4. It is available for free download on http://www.faa.gov

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  6. AMT 73 on Jul 10, 2019

    Maybe I didn’t make myself clear. I’m well aware unusable fuel is considered to be part of the empty weight and that a manufacturer only has to weigh every 10th airplane. Here’s what I’m asking, is the unusable fuel ever shown on a weight and balance form? I wouldn’t think so because the aircraft would have already been weighed with the tanks empty but with undrainable fuel on board. So the empty weight includes the unusable fuel as it should.
    So that’s what I’m asking: Is there ever a condition that would require unusable fuel to be part of the written weight and balance computation?

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  7. KDS on Jul 10, 2019

    There is a point in your original question that I suspect is just a matter of word choice, but I would just like to ensure you are are of it. You wrote “I’ve weighed my airplane”. While you can certainly weigh your airplane, you cannot create a legal weight and balance sheet unless you hold a mechanic certificate.

    That is aside of and unrelated to what Kris is explaining.

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