flyrotary@lancaironline.net Mailing List Archive

Bill,

I just ran a separate ground wire from one of the screws on the instrument sub-panel to the forest of tabs. It makes a lot of sense as the sub panel is mounted on a fiberglass frame, essentially insulating it from the rest of the airplane. Who knows how the ground path was completed. It probably wouldn't have hurt a thing to do the same with the other two sub panels.

Mark

On Mon, Sep 21, 2009 at 10:15 AM, Bill Bradburry <bbradburry@bellsouth.net> wrote:

Mark,

I copied the below from an msg from you last Oct.. Which pin on the PCM did you connect to ground? The only pin I can find in the instructions for the PCM that is identified as ground is pin 1 which is called out to be connected to pin 16 on the Controller? Did you splice this wire to ground or did you connect a different pin on the PCM?

“ Keep in mind that I had some data corruption problems similar to Al Gietzen. It seems to be a problem with fiberglass airplanes, so don't be surprised if you experience this too. With me, it always happened while on the ground. Last time it happened, I looked at each of the 3 tables and saw that only one was actually corrupted, so it is possible that it may have happened in the air, but since I was running above 3800 rpm (and operating in the upper table), I didn't notice any difference. Nobody really knows what causes this problem, but I seem to have fixed it by running a separate ground from the PCM to the forest-of-tabs ground. The thought was that the sub-panel was mounted on a fiberglass frame and therefore was isolated from ground. I have not had an episode since I added the ground.”

Bill B