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  #11  
Old 12-08-2018, 10:08 AM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
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Location: Hinckley, Ohio
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Quote:
Originally Posted by DaleB View Post
Hold the trim DOWN button for 5 seconds. That's what I do, since my trim indication is also highly erratic and essentially useless.
What if someday you get distracted, or rushed, and accidentally hold the trim UP button for 5 seconds by mistake???? Big ooops...

Very best thing is to fix root cause of all problems when they occur and ground the airplane as not airworthy until fixed.

You might want to read about this accident....http://www.vansairforce.com/communit...ad.php?t=97774
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Jim Stricker - EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC N86203
1130 hrs Flying 46 Piper J-3 Cub N6841H
Bought Flying RV-12 #120058 Oct 2015 with 48TT - Hobbs now 750

LSRM-A Certificate 2016 for RV-12 N633CM
Special Thanks... EJ Trucks - USN Crew Chief A-4 Skyhawk
MJ Stricker (Father - CFI) - USAAF 1st Lt. Captain B-17H

Last edited by Piper J3 : 12-08-2018 at 10:17 AM.
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  #12  
Old 12-08-2018, 10:44 AM
John-G John-G is offline
 
Join Date: Jan 2012
Location: Northeast Ohio
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Quote:
Originally Posted by bobg56 View Post
That's the thing with these firmware updates, it seems you keep trading off one problem for another which can be seen by the amount of versions they have for the D180 and I'm sure the Skyview has plenty as well.
Bob --

I don't agree with your assessment of your trim display situation. Being an avid daily reader here on the forums for the last 7 years, I can't remember reading about a D180 software revision causing flaky trim display indications. However, I have read numerous posts where intermittent trim displays have ultimately been attributed to a wiring/connector issue and in a few instances the trim servo unit itself. Although I have a SkyView, I can honestly say I have not seen a Dynon software revision for the SkyView cause any major disruptions in the SkyView's functionality .... in fact, it has been just the opposite.

I have to agree with Jim on this one, removing the trim indication from the D180 display and not looking into the root cause of the problem is not the solution, nor in the best interest of safety ... which we should all be striving for.

Suggest beginning your trouble shooting by either looking at the connector on the back of the D180 or looking first at the tail cone which is easier to access ... so I would start there.

The trim wiring connections at the tail cone have been notorious for developing issues like the ones you mention or the trim motor not moving. (As a side note, the newer RV-12's use a different (much better) connector at this location which you can retrofit to if you find this location to be the culprit). Have somebody GENTLY move the wires around a little while you monitor the D180 and see if the display locks up nice and solid and then can be made flaky by moving the wire(s) at the connector at the tail cone. You may want to actually verify solid voltages at the trim motor side of the connector at the tail cone since it is really easy to do so. The white/blue wire should have a solid 5 volts measured to ground (this voltage comes from the D180 so if it is not rock solid follow the wiring back to the D180). The white/green wire is the actual trim position sense wire and the voltage on it will vary from a low voltage to close to 5 volts depending on the position of the trim motor ... however, the voltage should be constant when the trim motor is not moving. Operating the trim motor will change the voltage higher or lower depending on direction of motor movement ... but when stopped, the voltage should be rock solid. The white/orange wire is ground, to check that, switch the meter to the ohms scale you should read a very low resistance to air-frame ground. If the 5 volts on the white/blue wire is found to be solid but the there is an issue with bouncing voltages on the white/green wire (on the trim motor side of the connector) the trim motor assembly is your culprit (or a bad crimp on the pin for the white/green wire). If all the above checkouts OK, check the white/green wire on the tail cone side of the connector ... if the voltages are bouncing around the pins at the connector are the issue.

If the connector in the tail cone checks out OK, I would suggest removing the connector from the back of the D180 and check to make sure the pins associated with power to the trim unit and the position signal on GP3 are tight in the connector with no corrosion and don't easily push back if a little pressure is placed on them. Obviously this connector needed to be removed to send your D180 in for the upgrade so this connector would be the next best place to look for your trim issue. If removing, checking and reinserting the connector does not fix your issue and the 5 volts was rock solid at the tail cone, I would remove the connector's shell and have somebody slowly move the associated trim wire EMS-37/23 and see if there is any change on your display. Take a voltage reading from pin EMS-37/23 to ground. Whatever the voltage reading is, it should be rock solid ... then move the trim motor up or down ... as the motor moves, you will see the voltage on this pin change wherever you stop the motor the voltage on this pin should remain steady. If it is not, you have a bad connector pin between the tail cone and the D180 connector.

If the voltages on EMS-37/23 & are rock solid at the connector then there is either an issue with the connector on back of the D180 unit or an internal issue inside the D180.

Hope you find the above helpful.

And PLEASE ... don't fly with the trim indicator removed from your D-180 display. Because, even though you may know how to get around the trim display issue, that doesn't mean at some point in the future somebody else may need to fly your airplane and unknowingly become another NTSB statistic.

Good luck with your troubleshooting.
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Last edited by John-G : 12-09-2018 at 09:06 AM.
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  #13  
Old 12-08-2018, 11:42 AM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
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Quote:
Originally Posted by JosephineJ79 View Post
Personal attacks such as calling someone "short-sighted" is in violation of posting rule number 7. Please delete that from your posts above.
Done... however, I'm entitled to my opinion. Safety should never be short-changed. Never...

Look at Lion Air Flight 610. Problem with pitch trim on flight prior to accident. Aircraft not airworthy on previous flight...
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Jim Stricker - EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC N86203
1130 hrs Flying 46 Piper J-3 Cub N6841H
Bought Flying RV-12 #120058 Oct 2015 with 48TT - Hobbs now 750

LSRM-A Certificate 2016 for RV-12 N633CM
Special Thanks... EJ Trucks - USN Crew Chief A-4 Skyhawk
MJ Stricker (Father - CFI) - USAAF 1st Lt. Captain B-17H

Last edited by Piper J3 : 12-08-2018 at 11:54 AM.
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  #14  
Old 12-09-2018, 09:20 AM
bobg56 bobg56 is offline
 
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Location: Peachtree City, GA
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Hey John, thanks for all that good info for T/S the trim problem. I'll get on it asap...the trim motor itself works without issues. I will follow your recommendations, also I'll call Dynon again. The reason I'm at 5.6 instead of 5.5 is that I had a bad auto pilot servo I sent to Dynon, they fixed it and sent it back with it at 5.6...I was not aware of Vans locking out the updates at 5.5 ...I updated the auto pilot system to 5.6 and had to send the D180 to Dynon to have it unlocked and brought to 5.6 because you can't lower the firmware back down, only up. This would have me removing my servos and AP74 to send back to Dynon. We (Dynon and myself) figured it would be best just to send in the D180...so now everything is at 5.6 and my trim indication is erratic...the D180 plug suggestion is the first thing I'll look at since maybe a pin got pushed back during removal/re installation...I thank all of you guys for your help...I've been an A&P for 40 years and I'm still learning things, especially when it comes to Experimental's, quite a bit different than my old C-170.
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  #15  
Old 12-09-2018, 12:55 PM
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DaleB DaleB is offline
 
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Quote:
Originally Posted by Piper J3 View Post
What if someday you get distracted, or rushed, and accidentally hold the trim UP button for 5 seconds by mistake???? Big ooops...
And not that big of a deal. The stick works quite well to control pitch while you correct the trim. Even if said trim is severely out of whack when you take off. You've never once in your life missed setting takeoff trim?
Quote:
Originally Posted by Piper J3 View Post
Very best thing is to fix root cause of all problems when they occur and ground the airplane as not airworthy until fixed.

You might want to read about this accident....http://www.vansairforce.com/communit...ad.php?t=97774
I did, and after ten pages I still saw nothing relevant to this discussion.

If there is a defect that presents a safety issue, I'll ground the airplane until it's fixed. A wonky RV-12 trim indicator does not, to me, cross that threshold. If it does for you, then great... you're more than welcome to do as you see fit. My trim indicator works occasionally, but it's not stable or reliable, so until I have some time and suitable weather to tear into things in our hangar, my co-owner and I are both well aware of its state, and fly accordingly.
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Omaha, NE
RV-12 # 222 N980KM "Screamin' Canary" (bought flying)
Fisher Celebrity (under construction)
Previous RV-7 project (sold)
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  #16  
Old 12-09-2018, 01:00 PM
Mich48041 Mich48041 is offline
 
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The most likely problem is a bad connection as John G posted. If all of the connections seem to be good, then a 5K potentiometer could be substituted for the Ray Allen pot. Doing that will help to determine if the fault is wiring or inside of pitch trim servo.
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  #17  
Old 12-09-2018, 02:13 PM
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mike newall mike newall is offline
 
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What did you set your K Factor to btw ? I am in phase 1 testing and my fuel flow is waaaaaaay out !
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  #18  
Old 12-09-2018, 03:49 PM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
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Quote:
Originally Posted by DaleB View Post
You've never once in your life missed setting takeoff trim?
Haven't yet (knock on aluminum). Prior to the buying my RV-12 I owned and flew a J3-Cub for 23 years. Elevator trim (actually horiz stab incidence) is totally worthless on a Cub. Anytime you see a Cub on the ground, or in the air, the stab is trimmed full up. If you ever loose the up elevator cable on a Cub you're going to auger in - stab trim will not maintain a glide with/without power.

So now I'm flying a real airplane with full-functioning elevator trim and wing flaps to boot. I use a pre-takeoff checklist to remember to check these two items that I have not had the pleasure of using for all these years...
__________________
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Jim Stricker - EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC N86203
1130 hrs Flying 46 Piper J-3 Cub N6841H
Bought Flying RV-12 #120058 Oct 2015 with 48TT - Hobbs now 750

LSRM-A Certificate 2016 for RV-12 N633CM
Special Thanks... EJ Trucks - USN Crew Chief A-4 Skyhawk
MJ Stricker (Father - CFI) - USAAF 1st Lt. Captain B-17H
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  #19  
Old 12-09-2018, 07:54 PM
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DaleB DaleB is offline
 
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Quote:
Originally Posted by Piper J3 View Post
Haven't yet (knock on aluminum). Prior to the buying my RV-12 I owned and flew a J3-Cub for 23 years. Elevator trim (actually horiz stab incidence) is totally worthless on a Cub. Anytime you see a Cub on the ground, or in the air, the stab is trimmed full up. If you ever loose the up elevator cable on a Cub you're going to auger in - stab trim will not maintain a glide with/without power.

So now I'm flying a real airplane with full-functioning elevator trim and wing flaps to boot. I use a pre-takeoff checklist to remember to check these two items that I have not had the pleasure of using for all these years...
I use a pre-takeoff checklist as well... but nobody's perfect. Certainly not me. Anyway, I have taken off with trim set for landing. It takes about a second to realize what's going on and push, then (sheepishly, even if you're alone) reach for the trim switch and take the pressure off the stick.
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RV-12 # 222 N980KM "Screamin' Canary" (bought flying)
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Previous RV-7 project (sold)
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  #20  
Old 12-11-2018, 03:51 PM
bobg56 bobg56 is offline
 
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Location: Peachtree City, GA
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Smile

Problem solved, it was a wire in the tail cone that was loose at the wire block...it was the excitation wire. Re secured it and tie wrapped the wires securely. The thing that gets me is that I was certain it was the update that did it since it worked fine before, some coincidence, now I'm going to go dance in the street to celebrate, I flew for about 1.5 hours today and everything was ship shape...nice!
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