A320 ZFW Calculation

[k.swiss]

Hello Guys

Small question: If ZFW drops by 1T can you increase fuel uplift by 1T directly. Or is there something wrong in doing so?

Thanks - Swiss.

[FlightDetent]

Hello Guys

Small question: If ZFW drops by 1T can you increase fuel uplift by 1T directly. Or is there something wrong in doing so?

Thanks - Swiss.No. Check for resulting CG position is needed. In some marginal cases, you might run off the limits.


Edit: speaking of marginal cases: Even just removing the 1t payload should trigger the CG check, without adding anything.

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[oceancrosser]

If adding 1t of fuel for any airplane results in c.g. out of limits, something is seriously wrong. Fuel tanks are usually near the middle of the airplane and (except for trim tanks) fuel load results in limited change to c.g.
Generally you can say yes to the OPs question, unless you hit some other limit. Usually a ZFW limited flight can add fuel upto MTOW (or limited TOW) or Max Fuel Capacity. For a shorter leg MLW might be limiting. In which case reducing ZFW by 1t does allow adding 1t of fuel.

[k.swiss]

If adding 1t of fuel for any airplane results in c.g. out of limits, something is seriously wrong. Fuel tanks are usually near the middle of the airplane and (except for trim tanks) fuel load results in limited change to c.g.
Generally you can say yes to the OPs question, unless you hit some other limit. Usually a ZFW limited flight can add fuel upto MTOW (or limited TOW) or Max Fuel Capacity. For a shorter leg MLW might be limiting. In which case reducing ZFW by 1t does allow adding 1t of fuel.

Thank you for your reply oceancrosser and FlightDetent. A few questions to your reply.

1. @FlightDetent why will MLW become limiting if we substitute 1T of payload for 1T of fuel? The payload would have remained fixed for the flight so with that in mind, so will the fuel. We would not be adding to the MLW as 1T of payload has been removed to accommodate the 1T of fuel. That is my logic. Please correct me if my thinking is wrong.

2. @oceancrosser good point about the CG shift but as mentioned I do not think this will happen as wings are in the center. However will check the FCOM for this.

Thanks Gents.

[FlightDetent]

I did not say MLW might become limiting, as opposed to pointing out to watch for possible CG issues in marginal cases.

The usual LMC correction without the need for new CG is around 500 kgs on the type asked for.

Simply put, instead of saying YES - but, I said No. :)

OP: You left no clues about your background or the environment the question comes from initally. My post above stands valid without getting in the way of your logic 1).

oceancrosser Ever tried to work the CG for 19,8 @ 77?