The Cessna 177 is missing from the collection of Flight Gear aircraft. The Cessna 177 is in the standard AI aircraft folder of the later (Flight Gear 3) versions, which has many other aircraft such as the Dash 7 and the Saab 340. Viewing the model in G3D showed the model was detailed enough for use.
Steps
When creating a new aircraft or modifying an aircraft in Flight Gear the first step is to create a different folder for the modified aircraft files.
<description>Cessna 177 Cardinal Test</description>
<model>
<path archive="y">Aircraft/c177/Models/c172p.xml</path>
</model>
<PropertyList>
<path>c177.ac</path>
texture "177-tex.rgb"
The result:
A short hop showed that the model 'flies' without any problems although several error messages are show regarding animations and other things.
The 177.ac 3d file was imported into Blender, exported as .3ds and imported into Wings 3D
Bottom images:
The picture on the right is an attempt at a crude cabin: it hides the transparency or to be more accurate there are no transparencies, but the instrument panel shows through, and the vertical float above the runway does not seem to be affected by the position parameters.