missing landing gear

2 questions:
When I import certain aircraft from CFS2, the aircraft is there and appears to fly normal but the landing gear is missing and the control surfaces don't move, Why is this?
And,
What program is used to open up .MDL files? I have a registered Gmax program but that doesn't seem to do it. Is there a plug-in for .MDL files?
When I import certain aircraft from CFS2, the aircraft is there and appears to fly normal but the landing gear is missing and the control surfaces don't move, Why is this?
And,
What program is used to open up .MDL files? I have a registered Gmax program but that doesn't seem to do it. Is there a plug-in for .MDL files?