I believe that FS (makemdl) does NOT like part stretching/vertex level animations.
In all probability I bet you are correct. I'll give it a try and see what happens.
That said,
Kev could pull it off in Gmax without too much of an effort.
The key is to use the "Linked XForm" modifier. This will let him work on the object at its sub-object level.
Here is a short run down for the process.
Select the wing at its polygon sub-object level.
Choose the polys that make the left aileron. Go to the Edit Geometry rollout and select "Detach". When the Detach dialog opens choose "Detach To Element". This will isolate the polys; yet still keep them as part of the wing object.
Move up in the sub-object level to Vertex. Select the vertices on the leading edge of the aileron and the trailing edge of the wing i.e. where the aileron was detached from. Use the Weld to connect them back to the wing.
Next, create a small cylinder and place it inside the aileron near the leading edge, centered if possible for best pivot results. Set the pivot point on the cylinder through the Hierarchy tab and rename it to l_aileron.
Reselect the wing once again. This time go to its Element sub-object level and click the area that makes up the left aileron.
Now add the "Linked XForm" modifier to the stack. The "Linked XForm" only has one rollout called Parameters. In that rollout choose "Pick Control Object".
Go over to "Select by Name" or shortcut to it with the "H" key. When the Dialog opens pick the l_aileron as the control object. At this point look back at the "Linked XForm" Parameters rollout and you will see that the Control Object section has been updated with the name l_aileron. That