I got the OAT probe installed, and connected to the EIS 4000 back in mid-April before I did the last burst of road trips. The Grand Rapids OAT probe comes with six feet of wire, as I recall, and I understood that the wire could not be spliced [Update 26 June 2008 - apparently the OAT probe is a thermister, and the wire can be spliced. Thanks to Skylor Piper for noting my error, checking with GRT, and letting me know. I'm not sure why I thought it could not be spliced]. They will sell probes with custom lengths of wire, if requested. I knew that the standard length of wire would not be enough, so I made some measurements, estimated how long a wire I needed, and added a bit more just to be sure I had enough. When I ran the wire, I wanted to route it with other wire bundles, so it had some support, and those bundles made several detours to get around the passenger foot wells, the aileron pushrods, the front spar, landing gear boxes etc. As I ran the wire, the amount left was getting shorter, and shorter, and I became concerned that I might not have enough. When I finally got it all the way to the EIS 4000, I was very happy to see that I had three inches of extra wire.

I screwed up when I drilled the hole in the under-wing NACA scoop for the OAT probe - I went straight to the final size hole, and that large drill dug into the plastic and cracked it. I fixed it with epoxy today. I should have started with a small hole, and worked up in small increments. I put the OAT probe over to one side, to leave room in case I later decide to add an OAT probe for the Dynon EFIS.

The OAT is displayed at the bottom left on the EIS 4000 screen - it is showing 2°C, which compared well with the temperature shown on the thermometer in the hangar.