Tip for malfunctioning readings on Skyview

[woodmanrog]

For those who haven't already discovered it yet. I had erroneous engine temp readings pop up after about 65 hrs. of flying our new RV14A. The number 1 cylinder was fluctuating from 100 to 495 degrees, spinning like a top. Numbers 3 and 4 started out OK but then went to reading 100 degrees lower than they did one minute before. Here was the cure: All we did was trace the sender wires back to the spade connections inside the engine compartment. We disconnected and then reconnected each wire three or four times. All readings went back to normal. I guess a little vibration/moisture/corrosion took place and was eliminated by this process. I love simple fixes.

 

[Dynon101]

I had the same problem and Dynon recommend a barrel type connector where the two wires of the splice are inserted into the barrel and the conductors lay side by side and then an Allen head screw is used to tighten up the connection. Some heat shrink tube seals it up.

 

[Raymo]

The one's homebuilt101 refers to can be ordered from ACS at the following link.

https://www.aircraftspruce.com/catalog/inpages/eioverlapolc-1-10-05470.php?clickkey=107514

 

[Dynon101]

Yup...thats them!!!

I really do not see any better/more reliable way to splice thermocouple wires. The two bare conductors of the thermocouple wires lay side by side for about 1/4 inch of length so there is no dissimilar metals getting in between the thermocouple wires and the heat shrink seals them up nice.

 

[mrdaud]

OK, I've posted this before, but worth doing again.  There is a better way.  Get rid of any spade/barrel connectors!!!!  Use dedicated TC connectors made with the same metal as the wire, and easy to install.  Fixed all my problems.  You can purchase the connectors from Omega at www.omega.com.  There are male and female genders and J & K type connectors, and are reusable.  They are about 1/2" wide.  Well worth the small additional cost. If you are having TC connections problems, this is a guaranteed fix.
SMPW-CC-K-M  $2.45 ea
SMPW-CC-K-F   $2.95 ea
SMPW-CC-J-M   $2.45 ea
SMPW-CC-J-F    $2.95 ea

Omega also sells bulkhead "cannon plug" connectors with TC pin material. This provides a really nice, neat, safe, thru-the-firewall penetration for TC wires.

 

[vlittle]

Not a permanent fix. I've replaced all of the fast-ons firewall forward with barrel connectors. Not perfect, but much better.

The problem is that we are measuring microvolts here and any corrosion leads to an oxide film that produces a semiconductor junction. This messes with the measurements.

Sometimes, the vibration of the engine abrades the junction and it works properly, so on the ground you get wonky readings and in flight it's fine.

V

 

[woodmanrog]

One of my fellow pilots suggested going "old school" and merely making a mechanical splice by twisting the wires together, leaving the splice UNSOLDERED, then heat shrinking the splice. This kind of makes sense as you eliminate the possibilities if connector malfunction and still have wires that are easily separated if necessary. Thoughts from experts?

 

[mrdaud]

From a GE thermocouple training manual comment:

"Thus twisting, welding, soldering, crimping - they all work, until... until corrosion sets in between the connections. Thus, twisting is the least preferable over time because the metal is neither fused nor crushed together sufficiently to form what's termed "a gas tight connection."

I used to weld wires with a special TC wire welder, which is the preferred way, but, 1) welders are several thousand dollars, and 2) they are permanent connections.

I hate to beat a dead horse, but if you use the thermocouple specific connectors I've noted in response #4 above, you will fix your problems. They use the same metal as the TC wire. I've used these for years in industrial processes, and after many early problems with my Dynon supplied TC's and frequent emails back and forth with Dynon, I took my own advice and switched to these connectors. Since switching, I've had trouble free operation for over two years now. Not as cheap as twisting, but for only about $30, they are worth your risk. And they are reusable if you have to change thermocouples.

 

[woodmanrog]

N214ST,
Per your original suggestion, I ordered 20 of the barrel type connectors long before my last post. I had no idea how small these were. I did connect a couple of trial wires but they were a b***h to get them intertwined and then locked down. Thanks for the great info about the corrosion. I will put on the connectors when it finally cools down a bit in Florida.

 

[sglynn55]

I'm using Dynon's EMS and the thermocouple wires come with male blade connectors because I'm also using Dynon's engine transducer kit and the EGT and CHT wires come with female blade connectors. Are blade connectors okay to use for these TC connections? Or should I cut them off and use barrel connectors? My Piper production plane uses ring terminals and little screws.

Also what insulation do you wrap these with? Or is none needed since the blade connectors are insulated? Thanks

 

[vlittle]

I'm using Dynon's EMS and the thermocouple wires come with male blade connectors because I'm also using Dynon's engine transducer kit and the EGT and CHT wires come with female blade connectors.  Are blade connectors okay to use for these TC connections?  Or should I cut them off and use barrel connectors?  My Piper production plane uses ring terminals and little screws.

Also what insulation do you wrap these with?  Or is none needed since the blade connectors are insulated?  Thanks

Heat, vibration and contamination is very hard on these connectors. I replaced mine with barrel crimp connectors and my erratic temperature readings settled down.

V

 

[Raymo]

I'm using Dynon's EMS and the thermocouple wires come with male blade connectors because I'm also using Dynon's engine transducer kit and the EGT and CHT wires come with female blade connectors.  Are blade connectors okay to use for these TC connections?  Or should I cut them off and use barrel connectors?  My Piper production plane uses ring terminals and little screws.

Also what insulation do you wrap these with?  Or is none needed since the blade connectors are insulated?  Thanks

What Vern said. You can also use the ring style with screws, star washer and nut. These can be ordered from ACS as well.