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05-12-2018, 12:55 PM
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Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 5,298
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Quote:
Originally Posted by Canadian_JOY
Thanks for that feedback on the Autolite 386 plugs, Larry.
When you say they're a hotter plug than you would like, what symptoms are you seeing which drive you to this conclusion? Just plug color (white vs tan deposits), or other indications?
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No symptoms or problems observed. Insulators stay white with some grey area. No noticeable tan color. However, no ceramic erosion is observed.
A plugs heat range reflects it's ability to remove heat from the electrode area of the plug. Cold plugs remove a lot of heat and hot plugs remove less (transfering it to the head). Each engine requires a different heat range plug to maintain an optimum plug temp in the electode area. You want enough heat retained to burn off deposits, however, if it gets too hot it can cause pre-ignition.
From my research, the 386's are hotter than the BR 8's and 9's that have been well tested for our application and hot enough to burn off deposits. This is confirmed by the white insulators. My desire to avoid the hotter plug is to reduce the potential for pre-ignition. Clearly there is some margin left, as I have no indications of pre-ignition or detonation caused by pre-ignition after 400 hours. However, the margin is smaller than it could be.
Until I notice problems, I will continue with the 386's as I would like to avoid the issues with the adapters. However, on the 540 I am building I will likely get the adapters and go with the cooler 14mm plug options.
Larry
__________________
N64LR - RV-6A / IO-320, Flying as of 8/2015
N11LR - RV-10, Flying as of 12/2019
Last edited by lr172 : 05-12-2018 at 01:04 PM.
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05-12-2018, 05:57 PM
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Join Date: Sep 2017
Location: Marquette, MI
Posts: 27
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How I missed the dead plug on mag check
Quote:
Originally Posted by Danny King
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A disconnected plug wire would have been discovered with the first mag check when #4 cylinder cut out completely when the other mag or ignition was grounded! I guess I'm missing something here.
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A few of you seem perplexed as to how a cold plug could be missed on mag check. I'll try to explain.
The aircraft has one Lightspeed Plasma III ignition and one Slick Mag. Up to this point, I had only flown in aircraft with mags and was accustomed to an RPM drop of up to 125 RPM when grounding a mag. The run-up checklist in the POH for my new plane indicated that I should be looking for a symmetrical mag drop of up to 125 RPM, which is exactly what I got. Yes, the engine seemed a bit rough when the mag was grounded, but it wasn't like the plane was shaking apart. You might be surprised by how much a single electronic ignition running three plugs acts like a single magneto running four. Yes, something didn't seem exactly right, but given all the circumstances I described before, it became the norm for me in this plane.
Now that I have read more about the electronic ignition and talked to Klaus, I understand that there should be virtually no RPM drop when running only on the electronic ignition. With the experience I have now - seeing how well the engine runs on the Lightspeed alone - I would absolutely recognize this problem were it to occur again. Experience can be a really great teacher.
I believe that the POH for my plane was borrowed from another builder and was not adjusted to account for the fact that there is an ignition and a mag. I should not have been looking for a symmetrical RPM drop and certainly not 125 RPM when grounding the mag.
Does that make any more sense?
__________________
RV-7A O-360 A1A
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05-12-2018, 06:22 PM
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Join Date: Sep 2017
Location: Marquette, MI
Posts: 27
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Quote:
Originally Posted by BobTurner
I like your attitude. Having said that, let me remind you that you bought an experimental airplane, with an experimental ignition system. It may well be that there is no other airplane in the world exactly like yours, so mechanics, cfi?s, etc., can easily be confused by what is normal, or not, for your airplane. For example, I have been in a fair number of Cessnas with a fouled plug or other malfunction, and on a mag check they ran so badly that it was clear that something was wrong. But perhaps your experimental ignition was able to smooth over the roughness due to the loss of one cylinder, I don?t know. As a non-builder, but PIC of an experimental airplane, you have a significant responsibility in your hands. Yes, consult others, but ultimately the responsibility for safe and legal flight rests with you.
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I appreciate your comments Bob and you make a great point. I guess it's clear that at the time of purchase, I was, and maybe still am, not up to the responsibility of ensuring safe flight. In my non-aviation life, I am accustomed to consulting with those more knowledgeable than me and placing some amount of trust in those individuals' hands.
In this case, I spent some time getting to know the builder and visually inspected the quality of his work. I paid an A&P to do a thorough inspection of the aircraft (and he confirmed the quality of the build). And I flew with a CFI who had some time in the aircraft. Each of these individuals knew and understood far more than me about this aircraft in particular, and aircraft systems in general.
I knew that my familiarity with the plane was limited, so I had all of these resources involved to help make sure that flight in the aircraft was safe. However, I still failed to ensure safety. It wasn't the fault of any of these fine gentlemen that I flew around for 80 hours with only 7 plugs firing - it was my fault as PIC. I get that. You don't know what you don't know, until you do, then you post it on vansairforce.
So many things had to line up just the wrong way for this whole ordeal to happen the way it did. If only I had flown the plane before the pre-buy, I would have known what was normal and recognized the problem. If only the builder had ferried the plane to the pre-buy instead of his CFI, he would have recognized the problem when we did our first run-up. If only my A&P had gotten in the plane and heard it run on the ignition, maybe he would have recognized the roughness.
Anyway, we got it all working now, and I'm having a boatload of fun flying that little plane around. I'm grateful for this community and will remember to come back the next time I have a squawk like this. Thank you for your kind words, and also your harsh words.
__________________
RV-7A O-360 A1A
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05-13-2018, 08:29 AM
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Join Date: May 2017
Location: Epsom
Posts: 1
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Klaus has really good manuals provided for this system when it?s installed. They should be with the original aircraft paperwork. If you need a copy I?m sure he will provide it.
In the document there are clear warnings about operating the system with disconnnnected or broken leads that can damage the ignition coils.
Also, there are special considerations regarding the spark plug heat ratings not discussed here.
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05-13-2018, 10:18 AM
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Join Date: Oct 2005
Location: 08A
Posts: 9,500
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Quote:
Originally Posted by jbell2355
You might be surprised by how much a single electronic ignition running three plugs acts like a single magneto running four.
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It's a waste spark CDI.
The initial symptom may have been a single plug not firing, as the disconnected plug wire arced to the nearest engine metal. If so, the paired plug on that coil would have fired normally...until the excessive voltage rise burned though the insulation on the secondary windings. Now the coil is failed. The result would be two dead cylinders when the mag was grounded. It would be hard to overlook.
I don't recall reading how it was eventually determined you had a bad coil, or what else was replaced at the same time. Can you fill the blanks?
And BTW, why replace two pistons?
__________________
Dan Horton
RV-8 SS
Barrett IO-390
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05-13-2018, 08:33 PM
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Join Date: Sep 2010
Location: Charlotte NC
Posts: 1,168
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Quote:
Originally Posted by jbell2355
A few of you seem perplexed as to how a cold plug could be missed on mag check. I'll try to explain.
The aircraft has one Lightspeed Plasma III ignition and one Slick Mag. Up to this point, I had only flown in aircraft with mags and was accustomed to an RPM drop of up to 125 RPM when grounding a mag. The run-up checklist in the POH for my new plane indicated that I should be looking for a symmetrical mag drop of up to 125 RPM, which is exactly what I got. Yes, the engine seemed a bit rough when the mag was grounded, but it wasn't like the plane was shaking apart. You might be surprised by how much a single electronic ignition running three plugs acts like a single magneto running four. Yes, something didn't seem exactly right, but given all the circumstances I described before, it became the norm for me in this plane.
Now that I have read more about the electronic ignition and talked to Klaus, I understand that there should be virtually no RPM drop when running only on the electronic ignition. With the experience I have now - seeing how well the engine runs on the Lightspeed alone - I would absolutely recognize this problem were it to occur again. Experience can be a really great teacher.
I believe that the POH for my plane was borrowed from another builder and was not adjusted to account for the fact that there is an ignition and a mag. I should not have been looking for a symmetrical RPM drop and certainly not 125 RPM when grounding the mag.
Does that make any more sense?
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I can verify on my aircraft with 10 to 1 pistons and dual light speeds at 1700 RPM doing a mag check the engine is very smooth on 3 cylinders. Watching for the EGT rise is how I perform my run ups.
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05-14-2018, 08:40 AM
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Join Date: Apr 2015
Location: Houston, TX
Posts: 11
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Quote:
Originally Posted by jbell2355
... Given the situation,I had confidence in the airworthiness of the plane, and would have
expected the CFI to point out any abnormalities...
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This is a great discussion on the importance of preflight checks. Through this whole discussion this statement has stood out the most, mainly because it is the exact opposite from my focus during preflight.
I approach the preflight checks (before taxi, taxi, and before takeoff) with the mindset that the airplane is not airworthy. The checks slowly put together the "proof" that it actually is.
Knowing why every line item is in the checklists is the key. How are you supposed to determine if sub-par performance of a checklist item is a "safety of flight" issue unless you understand what it is telling you?
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05-20-2018, 05:40 AM
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Join Date: Sep 2017
Location: Marquette, MI
Posts: 27
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Quote:
Originally Posted by DanH
It's a waste spark CDI.
The initial symptom may have been a single plug not firing, as the disconnected plug wire arced to the nearest engine metal. If so, the paired plug on that coil would have fired normally...until the excessive voltage rise burned though the insulation on the secondary windings. Now the coil is failed. The result would be two dead cylinders when the mag was grounded. It would be hard to overlook.
I don't recall reading how it was eventually determined you had a bad coil, or what else was replaced at the same time. Can you fill the blanks?
And BTW, why replace two pistons?
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Thanks for your comments Dan. No pistons were replaced...I misunderstood my mechanic and have since gone back to the engine shop to verify exactly what they replaced.
I figured out it was the coil by talking with Klaus at Lightspeed. I explained all that had happened up to that point and he immediately recognized that the coil would be burnt out and told me so.
He did not mention anything about the burnt up coil also killing spark to #3. Based on my observations, I do think that #3 was firing.
__________________
RV-7A O-360 A1A
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05-20-2018, 05:52 AM
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Join Date: Mar 2013
Location: Flathead Lake Montana - 8S1
Posts: 334
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In 35+ years of having one LSE on the planes, I've learned (the hard way) to always carry a spare new coil. One failed mid-flight, the other on the ground. Two failures in ~5,000 flight hours.
Just for reference, 2 Slick mag failures in the same 5,000 hours.
__________________
'83 LongEZ - N888EZ 3,671 hours
'89 LimoEZ - N26EZ 686 hours (sold)
A couple of Glasairs and a Lancair 320...
Next: a RV14 need something to build
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05-20-2018, 09:50 AM
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Join Date: Oct 2009
Location: Victoria, BC, Canada
Posts: 3,932
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I'll ask again just in case this was missed... Does anyone know what the light-coloured buildup is on the face of the pistons? Is it lead?

__________________
Rob Prior
1996 RV-6 "Tweety" C-FRBP (formerly N196RV)
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