It would be interesting to get Air Zermatt's angle on this. EMS B429 in the mountainous country of Switzerland, limited to 7000lb (3175kg) mtow by EASA rules.
This is a
VERY simplistic look at the numbers, and I'm sure more bits and pieces need to be included here. Bell say in
this doc the empty weight of a 429 1P-IFR is 1911kg. Aerolite told me recently their HEMS kit for a 429 is 108kg. Full fuel is 821 litres x 0.8 (rule-of-thumb!) = 657kg.
So, 3175 -1911 - 108 - 657 leaves 499kg for the people, EMS supplies and whatever else you need to add to "Empty weight" to make it flyable. For example, Aerolite's number includes an oxygen rack for two 5 litre bottles, but not the bottles... The "Cabinet for medical equipment" will not include the weight of its expected contents. The basic weight will not include avionics options. And so on.
Air Zermatt also have a hoist which would add another 40kg or so. Thorond0r will need to find the weight of floats...
Anyone else please chip in with any other weights which need to be considered her? Or a calculation of range based on how much there is really left for fuel given the reserves needed when you take into account two pilots, one (or two?) medical specialists and the patient....