September 21, 2004

The RPM indication on the ACS2002 has been occasionally intermittent during the past week. Basically, only when the engine is cold, it would drop to zero RPM right after takeoff, and then a minute or so later it would come right back -- and would be fine for the rest of the flight. I assumed it was either a vibration issue, i.e. something that only happened when the engine was pulling 2600+ RPM or whatever, or maybe it was a temperature range thing. It wasn't consistent.

Tonight, I popped my access panels open to inspect the wiring at the analog box. Everything looked totally hunky-dory. Hey, thank goodness I've got these access panels, huh? Sure makes life easy.

I removed and re-seated the wires and buttoned everything back up. Since we all know I'm writing this weeks later, I may as well expand on what happened. I flew it again the next day, and the problem happened again. I pulled the top cowl off and inspected the wiring at the RPM sensor (which is a sensor that screws into the magneto), and everything looked fine. I removed and re-secured all the connections just to make sure...to no avail. When I flew again, I saw that the RPM sensor dropped out when the oil temp was between about 140F and 160F. Sure looked like a temperature range issue with the sensor. I figured I'd have to replace the RPM sensor.

I emailed the guys at Advanced Control Systems letting them know what the issue was. I swear it wasn't two days later when I got a brand new RPM sensor in the mail. Love it. Will install it when I change the oil in a week or so. I can live with the problem until then.

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Dan Checkoway ()