I found a great explanation online in how to create a log list of all the Lvars for an FSX/P3D add-on aircraft by using FSUIPC
Here is a link to the directions
http://npanel.project.free.fr/wp/?p=595
This may be old hat for many of you but it is an easy way to get a list of the Lvars. You can then create script including a fsx_variable_subscribe call containing the Lvars you want to investigate. You only need an empty callback function with no arguments and the values are still tracked. You can look at these values in real time while running your dummy instrument and operating the sim to see what the values are in Air Manager's Viewer window ( in the create tab).
I might add that Corjan is working on a way in a future version to generate this list right from within Air Manager without need for FSUIPC.
Lvars list for an Airplane
Lvars list for an Airplane
Russ Barlow
Air Manager Evangelist
Air Manager Evangelist