Minimum ZFM ?
 

What the purpose of having a limitation for MINIMUM zero fuel mass ? For instance, the aircraft I now fly has a limitation stating Minimum ZFM is 14120lbs?

Thank you.

That would be the Hawker 800XP wouldn't it?
I've got one (of many!!) manuals open and funnily enough, it's not defined. (Hawker 800XP Pro Line 21 AFM, Section 6 W&B) (Flight Safety)
Nearest I can find is Minimum Operating Weight - The minimum weight as which the gust criteria for structural integrity has been shown.

I'll have a look at the manuals CAE gave us, if that does not answer it, I'll "phone a friend". :ok:

A300-B4 freighter has a minimum zero fuel mass of 191800lbs although the empty mass is about 181000lbs. So if we have no payload we carry about 11000lbs of ballast fuel.

I was told that this minimum mass was the lowest that was tested for in the development of this aircraft, as with pax equipment it would never be less than 191800lbs. So this is a certification limitation.

Airbus did not plan for a freighter version at the start.

The only time this has been a problem was when trying to fly from Sharja to Stansted direct with no load and full tanks required. The ramp guy could not understand why we could not go direct unless he could find us some freight or ballast. I think we loaded a lot of empty pallets to solve the problem.

Hope this helps.

Vmca is determined for minimum weight .. generally this relationship will drive the AFM min weight limitation. Some searching in PPRuNe will find quite a few threads where this is looked at.

I emailed my tame TRE at Flight Safety at Farnborough. (Now he's contacting someone in Chester)

"the minimum is related to the structural integ with regard to gust factor the lighter the aeroplane the stronger it has to be to meet the gust factor vs. speed."

As the Hawker is 50 years "young", it's probably an old UK or Hawker Siddeley definition that has been lost in the mists of time.

I hope this helps. :ok:

Gust factor equally could be the limit. The operating pilot will have no way of knowing which might drive the AFM. Main thing is to observe the limit, as with all AFM limits - they are there for a reason.