I have been stuck on this question for several days now and can't see where I am going wrong.

Refer to the Echo System information.
BEW = 1980 kg 469.00 IU
The aircraft is loaded as follows
Row 1 – pilot 77 kg
Row 2 – 4 x 40 kg crates
Row 3 – 4 x 40 kg crates
Note the seats have been removed and the BEW reflects that.
Wing compartment 4 x 20 kg packages
Rear compartment 4 x 35 kg packages
Minimum fuel required for the flight stage is 100 kg.
5 kg metal bars are available as ballast.

If the load distribution is not changed, the minimum weight of fuel that is required in the main tanks as ballast fuel in order to keep the centre of gravity within limits is closest to:
a. Nil required.
b. 20 kg.
c. 50 kg.
d. 120 kg

So here is what I did:




After adding 45kg of ballast to the forward compartment I am out of balance by 3mm

ZFW (After) 2642 2683 709

3mm x 2642 kg / (2680mm-1780mm) =
3 x 2642 / 900 = 8kg of fuel ballast to add to the main tank

Thanks. I figured it out. My mistake was to ignore the Maximum Zero Fuel Weigh of 2630. When taking this into consideration I end up with 2696mm aft of datum, 16mm aft of limit at ZFW of 2627.

16 x 2627 / (2680-1780)=46kg which is close enough to 50kg.

The check needs to be done at ZFW. There's no need to consider the take-off condition since fuel in the main tanks can only move the CofG forward.

If you check the ZFW condition you will find that the CofG is 2722. Since the nose locker is empty, you can easily fix this by adding hard ballast to the empty nose locker. That works out at about 51kg which is still below the ZFW limit. You don't need any ballast fuel. (I don't recognise that as one of our questions).

Bob