I have just done a silly thing and corrupted my R4D-6 aircraft - without a copy !!.

I thought I might be able to delete and re-install just the R4D-6 from the CD but there is just an .exe file on there [plus other things].

Is this possible or must I delete all MAAM aircraft and start again ?

Thanks.

That exe file is the aircraft installer.  Go ahead and run it to re-install the planes to their original state.