Mass & balance

[thibautg78]

Hi,

Once again is struggle with one of my atpl question. I've got many troubles to understand the calculation process in mass&balance problems.

The following data applies to a planned flight :

Dry operating mass : 34 900 kg
Performance limited take-off mass : 66 300 kg
Performance limited landing mass : 55 200 kg
Maximum zero fuel mass : 53 070 kg
Fuel required at ramp :
- taxi fuel : 400 kg
- trip fuel : 8600 kg
- Contingency fuel : 430 kg
- alternate fuel : 970 kg
- holding fuel : 900 kg
Traffic load : 16 600 kg

Fuel cost at departure are such that it is decided to load the maximum fuel quantity possible. The total fuel which may be safely loaded prior to departure is :

a) 13 230 kg
b) 15 200 kg
c) 12 700 kg
d) 10 730 kg

Right answer is c : 12 700 kg

I don't understand how to figure it out. Can someone explain me?

Many thanks.
TG

[downwind24]

This is a max fuel problem so you dont need MZFM (or so i was taught) - if you take the lowest of the landing and T/off ie the landing at 55'200 you need to do as follows:

55200 (rlm) - 34'900 (dom) - 16'600 (t/l) = 3700

Then add:

Taxy fuel 400 and Trip fuel = 12'700 (as these are burned off before t/o and during flight)

I may not explain it in the best way but most importantly it makes sense in my head. Hope his helps

DW

[thibautg78]

All right, i think i understand now, thank you very much for having taken the time to solve this question.