Ok I know I need to add a new part in the MakeMdl.xml file, and I've added this:

Code:

<part_dictionary>
  <part>
      <Name>gear_doors</Name>
        <animation>
           <Parameter>
             <Sim>
               <Variable>??????</Variable>
               <Units>percent</Units>
             </Sim>
           </Parameter>
        </animation>
    </part> 

My question now is what should the Variable be? I will controll the wheel door with a xml gauge that is coupled to the engine rpm and hydraulic pressure

Oh it is for FS9 and FSX  and using Gmax