Wayne,

Make sure that the props are named with the correct tags:

If single engine:
prop_still      Visible when prop 0 is very slow.
prop_slow      Visible when prop 0 is slow.
prop_blurred      Visible when prop 0 is fast.

If 2 or more engines:
prop0_still      Visible when prop 0 is very slow.
prop0_slow      Visible when prop 0 is slow.
prop0_blurred      Visible when prop 0 is fast.
prop1_still      Visible when prop 1 is very slow.
prop1_slow      Visible when prop 1 is slow.
prop1_blurred      Visible when prop 1 is fast.
prop2_still      Visible when prop 2 is very slow.
prop2_slow      Visible when prop 2 is slow.
prop2_blurred      Visible when prop 2 is fast.

These are animated by FS not keyframes, but you must have the local coordinate pivot aligned with the world and properly centered on the spinner.

I usually give the spinner the tag name and link the prop blades to it.

Hope this helps.

What kind of aircraft?

How many engines?

Have you specified the correct number of engines in the aircraft.cfg file? 

Does the xxx.air file and aircraft.cfg match with each other?  What are you using as a starting point for these?

If you can provide more information, we can help.

Just to eliminate other things, re-spawn your aircraft using the default Cessna 172 as your " seed"  aircraft.

Make sure that in FSDS (which by your textures posting, I assume you're using), you've set your reference parts correctly - gear.center, gear.left, and especially the rear.scrape

In fact, you may want to add light.nav parts at the exact same location of the reference parts to make sure that maybe somewthing isn't out of whack.

The reason for using the Cessna flight dynamics is to get a "pure"  base, that you know works, and the only adjustments are the contact/scrape points.