Given

Aircraft empty weight = 689 kg

Empty aircraft index units = 19,522

Oil = 7 kg

Row 1: pilot and passenger = 110 kg

Baggage (baggage compartment) = 75 kg

Fuel = 140 litres

What is the maximum passenger weight, in kg, that may be carried in row 2 at take-off?

Ballast to add forumla:

GW (kg) x distance to move CG (mm) / new STA - current STA

GW = 980

Distance to move = AFT limit - current STA = 3,004 - 2,930 = 74 mm

New STA = 3600

Current STA = 2930

Therefore, ballast to add = 980 x 74 / (3,600 - 2,930) = 108 kg

So, 108 kg is max. passenger weight for row 2 with ZFW and take-off limits checked.

Finally, the key to loading an aircraft is not to exceed any limit. You are advised to check-plot weight moment or weight arm at both ZFW and TOW to ensure compliance.

Reference: Robson, David. "Chapter 10: Loading." Basic Aeronautical Knowledge (BAK). Darra: Aviation Theory Centre Pty, 2009. 329. Print.

Why it's related to AFT limit and moving the STA?

But finally we got the max. passenger weight rather than the distance that the CG need to be moved.

If the AFT limit is 3,004, then why the New STA can be 3,600?

I am just a bit confusing why this formula need to be used and why we always consider the Arm (mm)?

Hope someone can help me out. Thanks!

[Edited 2012-09-02 14:03:44]