Hi guys,

I’m currently doing a few practice exams in preparation for my perf exam and seem to have an issue with the following question:

With the passenger seats in rows 2 and 3 removed, an Echo has a basic empty weight and index units of 1950 kg and 467.5 adjusted accordingly. The pilot and co-pilot (@ 95 kg each) are employed to carry as many 4 kg boxes as possible. The cargo is sensitive and is only suitable for carriage in the passenger cabin and the rear compartment. If hard ballast is available in the form of 5 kg metal bars, the minimum amount of fuel as ballast required on this flight is closest to;
a) 67 kg.
b) 102 kg.
c) 59 kg.
d) 82 kg

I arrived at option A (it being the closest to my answer without exceeding it), but the answer given is C.

Here is my thought process:
I have 164kg in each of Row 2 & 3 (max weight that can be placed on the area otherwise occupied by a seat is 82kg; 2 seats in each row so 82x2) and 152kg in the rear compartment which gives me a ZFW of 2620kg. Hard ballast can only be 10kg before I hit max ZFW, so then following the fuel as ballast flow chart I arrive at 76kg.

Am I missing something here?

Any insight would be greatly appreciated!

Cheers.

Hi mate,

Did you calculate your new CG with the new weight of 2620 and whatever the new moment was with the hard ballast added and use that CG in your 'Weight to Add' flowchart?

Hi mate,

Yeah used the new COG and moment after adding the hard ballast.