Hi Bob and Richard (hope Wagga is not too cold for you Bob!)

Exercise 5.10 on page 5.40 says (under the table) Assuming MINIMUM Fuel is carried, and no limitations are imposed by RWY lengths, cruise is at 65% power, ignoring climb and descent, in each case above find:

1) Maximum take off weight permitted and 2) Ballast fuel required in the main tanks.

Based on the working on the first question, it would appear in this case no Fixed or variable reserve has been added to the flight fuel, so minimum fuel is only flight fuel in this case, rather than the minimum fuel including reserves and allowances in other parts of the book?

Is this right?

Brook

It's confusing as other parts of the book (I used the etext to look it up) say minimum fuel does include reserves. So by definition then it would appear that the question should say "Assuming ONLY FLIGHT FUEL" is carried (no reserves or allowances)".

Would I be correct in stating that?

Brook

This exercise asks a two-part question. The two parts are unrelated. Firstly it asks you to find minimum ballast fuel to add to put the aircraft within the CofG limits. So you use the flow chart for that and the present weight given in the question includes all of the fuel on board which would include all reserves. (Fuel required means required by the operator so it always includes the reserves because they are required).

The second part of the question asks you to find the maximum take-off weight permitted. The 'beetle' diagram for this calculation considers only the flight fuel because that represents the weight loss due to fuel burn-off during the flight. That doesn't mean that you are ignoring the reserves, it just means that, in checking to see what the take-off weight limit is, you must add the weight of fuel burn-off (i.e. flight fuel) to the maximum permitted landing weight.

It wouldn't be impossible that, after adding the required ballast fuel, you would be too heavy to land at the destination. I can promise that the examiner wouldn't be that cruel!!

By the way, if that did happen, you would have to leave some cargo behind. But that is not the issue here.

Thanks Bob - I managed to get the two parts thank goodness, but it was the definition of Minimum fuel as you say includes reserves, whereas in that exercise fuel is purely based on ETI hence flight fuel NOT minimum fuel. Run the calc's on one I think you will see what i mean - its Flight fuel only rather than minimum fuel.

So if I were updating the manual I would say "flight fuel" OR update the workings to include the Variable and Fixed reserves, as well as startup allowances. See if you can see what i mean - just have a look at the first example, there is no variable or fixed reserve in the workings!