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Random fluctuations on several readings...


Stuart

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Roger asked me to make a post about our recent experience with randomly fluctuating readings. Hopefully our experience will help someone else...

 

Our club has a 2008 CTLS. It gets a lot of use among 16 members, some of whom are in training.

 

Our troubles began with a call from a pilot who was about two hours away from home and getting high RPM alarms. He reported that the oil temperature was fluctuating drastically. It was dropping below 122 degrees frequently and setting off the RPM alarm. I told him it was an indicator problem and to fly it home if he could stand listening to the alarms.

 

After several cycles of crimping the connector and still having random alarms the issue was finaly resolved with new oil temp sender. No surprise here but this is where story gets good.

 

About two weeks of sanity later, a pilot reported several different alarms in flight. Oil temp, EGT, CHT and (get this) fuel pressure were all wildly fluctuating and causing alarms. Since this seemed to involve several systems we had our A&P clean the grounds on the aircraft. It didn't help. Pilots were still getting random readings and alarms anytime they flew. All the noise was cutting down the rental hours so getting it fixed was extremely important.

 

I sent an email to Dynon explaining the symptoms and what steps we'd taken to resolve it. Dynon was quick to respond with a statement that this sounded like one sensor or connector going bad resulting in voltage spikes cascading through the system causing the strange readings and alarms. They suggested disconnecting the sensor leads one at a time then running the engine to see if the readings/alarms were gone. They said disconnecting the bad circuit would result in better readings on the other channels.

 

After several hours of testing we discovered that one connector was bad on the right side CHT sender. Replacing that one connector solved the bad readings and alarms. We've been flying noise free now for about a month and a half.

 

Hopefully, this story will help someone in the future whose dealing with a similar issue.

 

Stuart

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Sorry Fred, I should have included that information. Our plane's avionics...

 

Dynon EFIS-100 and EMS-120, Garmin 696, GTX330 Transponder, SL40 Comm and Tru-trak ap.

 

The Dynon software hasn't been updated since we bought the aircraft. I plan to update it at annual in a few weeks.

 

Stuart

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Jim, you would have to check the version you have, then look at the revision note for the upgraded versions. Several of the last upgrades were for the autopilot, and if you don't have the Dynon autopilot I wouldn't think the upgrade would do much good.

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Everyone should do this one for the D100 &D120 because it has at least the oil temp fluctuation fix. The last one 5.4.3 had minor oil pressure bug fix. The D100 is mainly AP fixes.

If you don't do it nothing bad will happen, but it will take care of 1-2 annoying bugs.

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I just upgraded two airplanes with Dynon D100/120 to ver. 5.5 Everything went smoothly and the oil temp and press readings, while still fluctuating, are more stable than they were before. Also, one a/c has Dynon a/p and the new version has smoothed out some the pitch sensitivity we were seeing in our Piper Sport (which is pitch sensitive anyway) I say do it, just make sure you don't lose power on laptop or Dynons and follow the instructions to turn off other equipment as required.

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