A few of the tour operators have them installed , I guess some are recording on 3 or 4 cameras at once so you can get a pretty slick memory of your trip . If I recall correctly we installed some machines with cameras on tail ,just below RH door and a fish eye on the roof to capture the passengers . Check out Geneva's web site they have several STC's
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http://www.genevaaviation.com/products/p129.htm
http://www.platinumaviation.com/Main%20Pages/prod.htm
For the system I am familiar with.
Cal if you are out there is Jack still about ?.