Whilst explaining the loads on an aircraft to a class of ATPL students I found myself comparing MZFM and MLM. The loads on the main spar in both cases seem to be acting through pretty much the same points and a main stress point in each case seems to be the wing roots. The dynamic loads on landing are obviously considerably greater than the static loads for MZFM.
This makes me wonder, if you have to comply with landing loads at 10fps at MLM for a normal landing and 3G for an emergency landing for certification, why bother at all with the static loads at MZFM that seem on the face of it to be less limiting?
I suppose one answer could be that the continuous static loads at MZFM have a comparable effect on fatigue to the fewer short term dynamic loads on landing, is it that?
It also occurred to me that the lateral CP might be quite a bit further outboard than the main gear, leading to a greater moment on the wing root in flight than on the ground and making 'in flight' the limiting condition for MZFM. In this case the two limits would not be so easily compared.
A third possibility is that the main gear mounting points are the limiting structure for MLM and the wing roots for MZFM.
Are there any structural specialists out there that could give me a steer?