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In some weight and balance apps there is an option to "Use Max Zero Fuel Weight". Having never seen this in any of the aircraft I have experience flying, I am curious how this value is typically used in the calculation of an aircraft's weight and balance.

Can someone give me an example of how this value is used in a weight and balance calculation?

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Maximum Zero Fuel Weight is an operating limitation intended to protect the wing spar structure by limiting the concentration of load, relative to all up weight, borne by the wings in the middle of the span. In other words it limits spar bending loads at the wing roots imposed by the mass in the fuselage because any additional weight must be in the wing tanks where the additional load doesn't add to root bending.

Generically, Zero Fuel Weight can just mean all up weight minus usable fuel. However, when an instruction says to use "Max Zero Fuel Weight" it's saying to apply a published MZFW value that is an operating limitation. In your case you would enter the Max ZFW value from the airplane's Operating Limitations in the AFM into the app.

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  • $\begingroup$ I think your answer would be stronger if you reworded to say that the MZFW is one of the structural design weights. $\endgroup$ – JZYL Apr 10 at 1:35
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    $\begingroup$ For pilot purposes, it's an operating limitation. $\endgroup$ – John K Apr 10 at 2:43
  • $\begingroup$ I would tend to agree with this answer. The Learjet 35 has tip tanks. It does not have a published max zero fuel weight but instead a max zero wing and tip fuel weight. Learjet calculates the weight of the fuselage fuel as part of the latter just for the reason stated above. $\endgroup$ – wbeard52 Apr 10 at 13:33
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Zero Fuel Weight is the weight of the aircraft with everything loaded for that flight, minus useable fuel (Takeoff Weight minus weight of useable fuel).

The Zero Fuel Weight in your weight and balance calculations are just a reference mark. It is not used for much if anything in most flight applications since you should never get to within 30 minutes of your empty status. This reference is useful in calculating other reference points. One of which is your maneuvering speed (Va). If you know your Va at your takeoff weighting your Va at your Zero, it gives you an envelope to remain within when it is necessary to slow down to Va. Slowing down to your Landing Weight Va speed during turbulence is your best option.

Your Center of Gravity calculation is just as important. Keeping Takeoff, Landing, and Zero Fuel CoGs in the envelope ensures best performance for things such as spin recovery and stability during all phases of flight.

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  • $\begingroup$ The question isn't asking about ZFW, but about Max ZFW, or MZFW. $\endgroup$ – Ralph J Apr 10 at 3:38
  • $\begingroup$ Also, ZFW is used plenty for everything than shows fuel remaining in lbs or kg. Add current (or projected landing) fuel to your ZFW to get current GW or projected landing weight. About anything with an FMC has that functionality. $\endgroup$ – Ralph J Apr 10 at 3:48

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