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  #1  
Old 09-18-2014, 12:09 PM
f1rocket's Avatar
f1rocket f1rocket is offline
 
Join Date: Jan 2005
Location: Martinsville, IN
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Default Electrical Gremlins Showing their Ugly Faces

I have 100 hrs on my RV-12 and up to this point, they have been relatively bug free hours. In the past three weeks, I've started to see a couple of electrical gremlins surface. I find this very frustrating because there is nothing I dislike more than tracking down wiring problems.

My first problem is that the right EGT reading jumps all over the place and then quits altogether. I have messed with this one a little and I first suspected the connector clips in the engine compartment. I've adjusted them, reinserted them, etc but no joy so far. This problem comes and goes so it is hard to pin down.

Second problem is that Skyview is giving me "Standby Network Error" that comes and goes as well. This sprung up as I was returning home from The Badlands Fly In. According to the debug page, it says it is in the SV-EMS-220 harness pins 1/6. In looking at the Van's wiring diagram, it is saying that it is the oil pressure line yet the oil pressure is displaying fine.

Third problem is that my fuel flow meter is showing zero flow. I first noticed this on a test flight to check on the other two problems. Haven't dove into this one yet.

I dread tearing open the cabin and the boot cowl but have no choice at this point. Just as the Fall weather is getting good too.
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Randy Pflanzer
Martinsville, IN (II87)

www.pflanzer-aviation.com
Paid through 2043!
Lund fishing Boat, 2017, GONE FISHING
RV-12 - Completed 2014, Sold
427 Shelby Cobra - Completed 2012, Sold
F1 EVO - partially completed, Sold
F1 Rocket - Completed 2005, Sold
RV-7A - Partially completed, Sold
RV-6 - Completed 2000, Sold
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  #2  
Old 09-18-2014, 12:20 PM
DHeal DHeal is offline
 
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Location: Windsor, California
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I've had the same inconsistent EGT readings since Day One (now 76 hours) -- jumpy readings, no readings, sometimes they both work fine, next flight they are intermittent, one side works and the other doesn't, sometimes prior to start-up they both accurately show ambient temps but as soon as engine starts one of them gets the Big Red X, etc. -- I suspect it is in the wiring / connectors, but I can't seem to nail it down. Oh well, I'll keep chasing it.
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  #3  
Old 09-18-2014, 12:50 PM
PilotBrent PilotBrent is offline
 
Join Date: Dec 2011
Location: Hackettstown, NJ
Posts: 402
Default Jumpy EGT (and CHT) readings

Same issues here beginning at 10 hours but all now resolved. I was convinced the engine monitoring module was the cause at first, but it was all just the connectors. Ended up replacing the spade connectors for the EGT wires with butt connectors/shrink wrap. Haven't had a problem since.

Similarly, the CHT temp readings were intermittantly also erratic. I replaced both of them with new connectors and was careful to properly crimp them to the wires this time. The sensor wires for these are only 22 guage and I clearly didn't do a good enough job crimping them in the first place. Again, that was at least 15 hours ago and all seems to have been resolved.
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  #4  
Old 09-18-2014, 12:58 PM
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MacPara MacPara is offline
 
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Location: Tucson, AZ
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The EGT problem you describe started in mine around hour 5 on the Hobbs. Then around hour 8 it just gave up completely. I didn't bother as there is no mixture control to do anything about the EGT anyway and I decided to replace the sensor at the next annual which seem to have fixed this issue for others. I checked the wiring and crimping and it was fine.
The Standby Network has nothing to do with the sensors but is the backup network for all Skyview components to communicate with. Usually the primary network is in use until a problem is detected and the backup network would be the fallback to go to. This is the network that connects SV display to ADAHRS, servos and EMS and additional keys/knobs, etc.
If the problem occurs only occasionally you can assume that the wiring is ok (unless a crimp is going bad) and there is a good chance that one of the components is approaching an electrical failure. In my case it was a servo electronics board that went bad. Identifying the failing component is hard to do. You could keep the power to the servos off and see if you still see the issue. Then still you'd have to find out which one of the two it is and convince Dynon that you really do see issues with one when sending it in.
I do have a continuous backup network error for a while now when the servos are on, so I know that one of them is definitely bad. However, they work just fine on the primary network and I do not consider the servos essential as I can power them off at any time and fly by hand. Compared to the effort of digging down there outside of an annual and locating the culprit was not appealing to me at all.
If you see the backup network problem come up with the servos powered off I'd be more concerned as this would point to a possible problem with more vital components like the ADAHRS or the EMS. Unfortunately, it is possible that when one of the electronic components on the SV bus fails it might take the whole bus down with it (backup & primary). I have seen this happen with my early issues during the build caused by a bad servo. That could mean that you suddenly lose your complete avionic system, everything that is integrated with the SV. I think you might still get GPS data on the moving map as the GPS is connected through RS232 but the airspeed and altitude information and the compass from the ADAHRS would be gone.
The good news is that once the component failed for good, it is much easier to identify which one it is - after a, hopefully safe, visual landing.

I do hope that in your case it is a crimp slowly going bad (the bulk of connectors near the servo under the left seat pan comes to mind) and the electronics are doing fine. I can help you identifying the wires you might want to check when I get home to access the schematics. Let me know.
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Last edited by MacPara : 09-18-2014 at 01:01 PM.
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  #5  
Old 09-18-2014, 01:33 PM
Driftdown Driftdown is offline
 
Join Date: Jan 2011
Location: Clearwater, Florida
Posts: 264
Default

Quote:
Originally Posted by f1rocket View Post
I have 100 hrs on my RV-12 and up to this point, they have been relatively bug free hours. In the past three weeks, I've started to see a couple of electrical gremlins surface. I find this very frustrating because there is nothing I dislike more than tracking down wiring problems.

My first problem is that the right EGT reading jumps all over the place and then quits altogether. I have messed with this one a little and I first suspected the connector clips in the engine compartment. I've adjusted them, reinserted them, etc but no joy so far. This problem comes and goes so it is hard to pin down.

Second problem is that Skyview is giving me "Standby Network Error" that comes and goes as well. This sprung up as I was returning home from The Badlands Fly In. According to the debug page, it says it is in the SV-EMS-220 harness pins 1/6. In looking at the Van's wiring diagram, it is saying that it is the oil pressure line yet the oil pressure is displaying fine.

Third problem is that my fuel flow meter is showing zero flow. I first noticed this on a test flight to check on the other two problems. Haven't dove into this one yet.

I dread tearing open the cabin and the boot cowl but have no choice at this point. Just as the Fall weather is getting good too.
Before I did anything else, I would check all my ground connections and re-tighten them. Loose or disconnected grounds are a common problem but easy to fix.
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  #6  
Old 09-18-2014, 02:08 PM
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Bill_H Bill_H is offline
 
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Location: Peel, AR
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Randy - this thread might be relevant depending on the vintage of your wiring harness. http://www.vansairforce.com/communit...ad.php?t=90330
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  #7  
Old 09-18-2014, 07:52 PM
RFSchaller RFSchaller is offline
 
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Location: Phoenix, AZ
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I have th D180. But I occasionally get a high EGT alarm on my left EGT. It's annoying, but clears shortly after it occurs and only happens once in a great while. It's like the intake manifold pressure indication - nice but not much use in practice.
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  #8  
Old 09-19-2014, 06:09 AM
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f1rocket f1rocket is offline
 
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Thanks for all the information and the suggestions. I appreciate the help.

I plan to swap out the connectors on the EGT probe. I don't like the spade connectors and will insert some slip blade connectors. If that doesn't work, I'll order a new EGT probe.

On the network error, this doesn't have anything to do with the servos. My harnesses were built this year in February so they are the latest. It's telling me that it's having trouble communicating with the EMS module. I "suspect" that I may be putting too much strain on an end wire (terminal 1) and that is causing the intermittent problem. The manual is not clear on this problem and I may need to talk to Dynon to make sure I am debugging this correctly.

I did encounter a problem on the way out to the Badlands Flyin that I hadn't seen before. All of a sudden, my EFIS went black and then re-booted. Not sure if that is related to any of these problems or a portend of bigger gremlins growing inside the equipment.

Thanks for your comments. I'd like to hear more from anyone who has had similar experiences.
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Randy Pflanzer
Martinsville, IN (II87)

www.pflanzer-aviation.com
Paid through 2043!
Lund fishing Boat, 2017, GONE FISHING
RV-12 - Completed 2014, Sold
427 Shelby Cobra - Completed 2012, Sold
F1 EVO - partially completed, Sold
F1 Rocket - Completed 2005, Sold
RV-7A - Partially completed, Sold
RV-6 - Completed 2000, Sold
Long-EZ - Completed 1987, Sold

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  #9  
Old 09-19-2014, 06:50 AM
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Rick_A Rick_A is offline
 
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Location: Highland Village, TX
Posts: 1,343
Default EGT probe connectors

Not RV-12 (I'm building one, thus the interest) but I was having intermittent #1 EGT reading on my MVP-50.

I checked both crimps where the probe connects to the TC wire that runs into the cabin. Cleaned and re-seated them. No joy. Re-seated the connector behind the panel. Still no joy. Decided to order a new EGT probe.

The new EI probe came with a new type of connector http://buy-ei.com/portfolio/olc-1/. Rather than crimping on connectors, bare wire from the probe and bare wire from the TC wire go into each end of a barrel. A set screw is used to lock the wires in place.

I tried the new connector on old probe and it solved the problem!
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  #10  
Old 09-19-2014, 09:44 AM
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RV7Ron RV7Ron is offline
 
Join Date: Jan 2009
Location: Denver, CO
Posts: 590
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I've had two EGT probes go out in the first 100 hrs. These failures started with jumpy readings, followed by mostly going out...although every now and then they would flicker to life. I called Dynon, and although they were apparently out of warranty, they replaced them at their cost...kudos to them for that, customer service was excellent.

Once I replaced them, problem solved so I have to assume it was bad probes although I never recieved a failure analysis from Dynon (I had to send the faulty one in). They stated they shoudnt be failing in less than 100 hrs...but with two instances, I am not real confident in the quality of these.
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