Toonice. I'm no expert with the MB but I've found some CFS2 Gmax aircraft don't work too well in QC or missions. I downloaded the original version of the P-40M to check it out. It works fine in QC so I don't think this is the case in this instance.

I had to edit the Aircraft.cfg sim= entries before it would show up on the Free Flight menu. I also noticed the DP allegiance=10 (Australia) entry under the [MISC_DATA] section. If you're using the default country.cfg I suggest changing this to 1 (Britain) or 3 (US). Alternatively, you can add the extra countries by downloading the authorised updated country.cfg here. http://www.microsoft.com/games/combatfs2/articles_SDK_countryfile.asp

I also suggest reconfiguring the RNZAF P-40 as a separate aircraft. Aircraft configured with multi-texture options should not cause a problem in CFS2 but I noticed a texture conflict between the 2 versions. This can be done quickly by deleting the Aircraft.cfg [fltsim.0] entry & renaming the [fltsim.1] header to [fltsim.0]

I didn't have time to check all this out in a mission. Hope this gives you some ideas.