I don't know what to say. I use whatever un-zip utility comes with Vista. It has unzipped every file I've downloaded with no problems. But in this particular case, the .air file is missing,
all folders are empty except for the "Documentation" folder, which has a PDF file, and the texture folder, which only contains the thumbnail.jpg, no BMPs. I've opened every folder, all of them, and they are empty, with the exceptions mentioned above. I installed *exactly* per directions in the "Read Me".
FSX Eurocopter AS350 Package
Original by FSpainter/Florian LAROYE
IMPORTANT: FSX Install.
This aircraft does not install like others.
Put whole folder FSXAS 350BA into Simobjects\Rotorcraft. Look under 'Eurocopter' and you will find it.
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FSX Comments
Comments.
Gauges/VC: All seem OK. Allow gauges if prompted.
Glass: - visible. Seems full FSX compatible!
All else seems OK. This is a great helicopter
This aircraft is not modified in any way. Full credit to the great talents of the original designer
FSX Compatible & tested. Thumbnails added.
I found this great helo in my FS2004 collection & as it works fine in my FSX SP2 I have tested it & added thumbnail to make it easier for FSX users.
Thumbnail for FSX by Danny Garnier
I make known FSX compatible aircraft for Simviation.com
raider911@gmail.com May 2008
Nothing could be simpler.
The one you tested was downloaded from the site, right?
If so, it's prossibly some "Vista Mystery" caused by my machine. For some unknown reason, it's not extracting that *particular* file correctly. I guess I'll have to settle for the GMAX from the FS9 heli page 9, mentoned above. It works and looks great too, and had 5 textures.

Sorry to be a bother