Spark plug wires?

deyoung

deyoung

Line Up and Wait
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Chris
What's the magic in finding spark plug wires? My usual sources of aviation stuff (Aircraft Spruce, MyPilotStore, etc.) don't seem to carry spark plug wires...

My PA-28-235 failed a run-up mag check today, and the wires are pretty old anyway, so I think I may just replace them all at once... if I can find any that is...
 
Good call.

If you have Champion plugs replacement them while you are at it. ;)

Depending on which mags you have not a bad idea to pull them and have them inspected or rebuilt. Ignition systems on a piston engine are fairly important. ;)
 
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Geico266 said:
Good call.

If you have Champion plugs replacement them while you are at it. ;)

Depending on which mags you have not a bad idea to pull them and have them inspected or rebuilt. Ignition systems on a piston engine are fairly important. ;)
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why would you replace the plugs if they are not the problem?

He might better do the trouble shooting and fix the cause.
 
Tom-D said:
why would you replace the plugs if they are not the problem?

He might better do the trouble shooting and fix the cause.
Click to expand...

Because Champions develope high resistance causing hards starts..... and they suck. :lol:

A failed run up usually means mags. New fine wire plugs eliminates spark plugs from the problem list. Do the work yourself and pay for the plugs. ;)
 
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What was it doing on runup?

Do you have a engine analyzer like a JPI? What was it showing for EGTs?

What kind of mags and how long since they were checked?

If you're running slicks....
 
Tom-D said:
What are these ?

http://www.aircraftspruce.com/catalog/eppages/kellyharness.php
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Those represent a "searching failure" on my part. ;)

James331 said:
What was it doing on runup?

Do you have a engine analyzer like a JPI? What was it showing for EGTs?

What kind of mags and how long since they were checked?

If you're running slicks....
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No engine analyzer; basic unit-less EGT didn't show anything unexpected, but everything was still fairly cold as this was the first start of the day.

On runup, all good until the mag check; right mags fine, left mags gave excessive rpm drop (~225-250, where 125-150 is normal) and rougher than usual running. No problems other than this, but as this was out of the ordinary and also out of recommended limits I scrubbed the flight. Probably one plug not firing, I'm guessing--maybe plug, maybe wire. Or maybe something I haven't thought of.

Slick mags, both overhauled about 150 hours ago.
 
deyoung said:
Those represent a "searching failure" on my part. ;)



No engine analyzer; basic unit-less EGT didn't show anything unexpected, but everything was still fairly cold as this was the first start of the day.

On runup, all good until the mag check; right mags fine, left mags gave excessive rpm drop (~225-250, where 125-150 is normal) and rougher than usual running. No problems other than this, but as this was out of the ordinary and also out of recommended limits I scrubbed the flight. Probably one plug not firing, I'm guessing--maybe plug, maybe wire. Or maybe something I haven't thought of.

Slick mags, both overhauled about 150 hours ago.
Click to expand...


Plugs & wires, do it yourself. Takes away the worry. ;)
 
deyoung said:
Those represent a "searching failure" on my part. ;)



No engine analyzer; basic unit-less EGT didn't show anything unexpected, but everything was still fairly cold as this was the first start of the day.

On runup, all good until the mag check; right mags fine, left mags gave excessive rpm drop (~225-250, where 125-150 is normal) and rougher than usual running. No problems other than this, but as this was out of the ordinary and also out of recommended limits I scrubbed the flight. Probably one plug not firing, I'm guessing--maybe plug, maybe wire. Or maybe something I haven't thought of.

Slick mags, both overhauled about 150 hours ago.
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Before you get crazy replacing things, the most likely culprit is lead fouling. Pull the plugs from the number two mag and check to see it there is any lead fouling in there. The lower plugs are most prone. If there is any little silver balls or crap in there, clean it out with the plug vibrator, or if you have one, bead blast it. At the very least you can pick it out with a dental tool.

If the plugs all look great, then check the wires. I would have thought that the wires were all checked 150 hours ago though...:dunno:
 
I had something similar.

But I had a smooth drop

Try to burn it off on the bad mag.

When it happened to me I had about a 250rpm drop, all EGTs were the same on the bad mag with a smooth drop, I couldn't burn it off. This was where I said to myself "self, this is going to get expensive"

Turns out one of the slicks, which were just 20ish hours out of annual and prebuy, decided to checkout.

I ended up ditching the crap slicks and put two bendexs with harness on.

Hope that's not your case, but if you read up on slicks...
 
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Tom-D said:
why would you replace the plugs if they are not the problem?

He might better do the trouble shooting and fix the cause.
Click to expand...

Because later he can complain how expensive ownership is?

A $5 volt ohm meter can detect a bad plug.

I just flew an O360 home which the owner complained of roughness during ground run. I didn't notice it but when I ohmed his plugs I knew he was right. One of the 4 old plugs measured around 33 megaohms with the other 3 in the 20k range. All of the newer plugs were under 2500 ohms.
 
bnt83 said:
Because later he can complain how expensive ownership is?
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Hey, I'm still completely learning here...

I have no desire to complain, and I'm willing to pay the costs of ownership, but I also don't want to pay any more than I need to - this is why I'm asking. ;)
 
Find a clear area and do a higher power run up. Get your rpm up and lean it until it stumbles. See if you can clear it up. One mag drop event shouldn't send you to collect new parts.
 
deyoung said:
Hey, I'm still completely learning here...

I have no desire to complain, and I'm willing to pay the costs of ownership, but I also don't want to pay any more than I need to - this is why I'm asking. ;)
Click to expand...

A wealth of learning can be found on on ..... wait for it..... a homebuilder website. www.vansairforce.net There you will find page after page of spark plug experiences etc. Google is decent too. "aircraft spark plug" would likely lead to something like this:


http://www.tempestplus.com/Portals/...e/Sparkplug Cleaning The Right Way 081412.pdf
 
Stewartb said:
Find a clear area and do a higher power run up. Get your rpm up and lean it until it stumbles. See if you can clear it up. One mag drop event shouldn't send you to collect new parts.
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:yes:


If you can't get rid of the roughness remember that misfiring (open) plugs adds a lot of stress to the magneto. If the plug is shorted out I don't think that would hurt a mag, but excessive resistance can.
 
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Start with pulling the lower plugs and inspecting them for lead fouling. You can reuse the copper gaskets a couple of times, but you should plan on buying 16 or so of them to have available to use. That should last you a couple of years.

If that is not it I would recommend hitting the log books. How long since the last magneto overhaul? How long since the last magneto inspection? How long since new wires? How old are the plugs?

If the magnetos need to go out for inspection or overhaul they can install a new harness for a little extra.

Which engine do you have? (The whole engine identifier, not just the O-320 or O-360 part. For example, my Tampico has an O-320-D2A.) That will tell us what kind of magnetos you have.

BTW, I have the Tempest fine wire plugs and love them. They were not cheap...

Jim
 
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Kiddo's Driver said:
BTW, I have the Tempest fine wire plugs and love them. They were not cheap...

Jim
Click to expand...

They are actually a better deal over the life of the engine than massive electrode. The save these headaches, loss of flights because of bad mag checks. and 1 set will go to TBO rather than buying a new set every 500 hours.
 
bnt83 said:
If you can't get rid of the roughness remember that misfiring (open) plugs adds a lot of stress to the magneto. If the plug is shorted out I don't think that would hurt a mag, but excessive resistance can.
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I've seen both - electrodes missing and the mag fired that plug just fine. We replaced it and saw no difference in the mag drops.

As far as the high resistance harming the mag, ?? good theory, But I doubt it would shorten the mag's life by 10 minutes.

Proper trouble shooting for a high mag drop is to remove and clean & gap the plugs, test the wires & Mags.

If it happens way to often, check pilot's ability to lean.
 
deyoung said:
Hey, I'm still completely learning here...
Click to expand...

The first lesson in ownership, is to find a good A&P that will properly care for your aircraft at a reasonable price. and not depend a web page for trouble shooting.
 
bnt83 said:
A $5 volt ohm meter can detect a bad plug.

I just flew an O360 home which the owner complained of roughness during ground run. I didn't notice it but when I ohmed his plugs I knew he was right. One of the 4 old plugs measured around 33 megaohms with the other 3 in the 20k range. All of the newer plugs were under 2500 ohms.
Click to expand...

Suggest that you might want to check your multimeter. In the first place, a $5 meter will NOT go to 33 Megohms. And, as I recall, resistor plugs are usually in the 5k range, not the 20k range. YMMV.

Jim
 
Tom-D said:
They are actually a better deal over the life of the engine than massive electrode. The save these headaches, loss of flights because of bad mag checks. and 1 set will go to TBO rather than buying a new set every 500 hours.
Click to expand...

A couple of posts back you were advocating keeping the old plugs? :dunno:
 
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weirdjim said:
Suggest that you might want to check your multimeter. In the first place, a $5 meter will NOT go to 33 Megohms. And, as I recall, resistor plugs are usually in the 5k range, not the 20k range. YMMV.

Jim
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Too bad no analyzer, easy to spot a bad plug without so much as a screw driver.
 
weirdjim said:
Suggest that you might want to check your multimeter. In the first place, a $5 meter will NOT go to 33 Megohms. And, as I recall, resistor plugs are usually in the 5k range, not the 20k range. YMMV.

Jim
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:yes:

Take a set of Champions and test them. The resistance is usually all over the place. Honestly, I don't know how the FAA allows them to be sold.
 
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weirdjim said:
And, as I recall, resistor plugs are usually in the 5k range, not the 20k range. YMMV.

Jim
Click to expand...


I hope not because 5k is where Tempest recommends trash bin. Maybe read it again?

A brand new out of the sleeve RHM38E measured 12XX ohms.
 
Geico266 said:
:yes:

Take a set of Champions and test them. The resistance is usually all over the place. Honestly, I don't know how the FAA allows them to be sold.
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I got: (All champions)

Tops (unknown age but ugly) 23.7k 11.96k 83.6m? 40.6k

Bottoms (one year old, 54 hours) 2.15k 2.415k 1.27k 1.319k

as mentioned in previous, a brand new one was 1.2k range.

I ordered 4 new URHM40Es to replace the old ones.
 
Kiddo's Driver said:
If that is not it I would recommend hitting the log books. How long since the last magneto overhaul?
Click to expand...

Both were overhauled about 150 hours ago. The wires are pretty old; I can tell that by looking at them, but not sure exactly how old. The plugs were all still in decent shape at the last annual, three months/30-ish hours ago.

Which engine do you have?
Click to expand...

Lycoming O-540-B4B5

Thanks!
 
deyoung said:
Both were overhauled about 150 hours ago. The wires are pretty old; I can tell that by looking at them, but not sure exactly how old. The plugs were all still in decent shape at the last annual, three months/30-ish hours ago.



Lycoming O-540-B4B5

Thanks!
Click to expand...

How many hours on the plugs? And what brand?

May I suggest you watch this webinar about spark plugs.

http://www.eaavideo.org/video.aspx?v=1826468805001
 
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Slick magneto ADs:

81-16-05
80-06-05
74-18-05

Bendix magneto ADs:

82-20-01
82-13-01
82-11-05
81-12-06R1
80-17-14
79-18-06
79-12-07
78-18-04
74-26-09
94-01-03R2
94-06-09
2005-12-06

As long as the Slicks are assembled properly at the factory, they're fine. I've had no more problem with them than with Bendixes.

Sparkplugs: Reistance 1K to 5K ohms. Digital meters that use very tiny measuring currents sometimes get wildly high and inconsistent results, while my old analog meter gets a steady, reasonable reading. The same thing goes for measuring field resistance via the slip rings in an alternator.

Champion recently went to the molded-in resistor. Maybe their troubles will go away.

I prefer the REM37BY plugs for any engine approved for them. They resist fouling far better.

Dan
 
Dan Thomas said:
Slick magneto ADs:

81-16-05
80-06-05
74-18-05

Bendix magneto ADs:

82-20-01
82-13-01
82-11-05
81-12-06R1
80-17-14
79-18-06
79-12-07
78-18-04
74-26-09
94-01-03R2
94-06-09
2005-12-06

As long as the Slicks are assembled properly at the factory, they're fine. I've had no more problem with them than with Bendixes.

Sparkplugs: Reistance 1K to 5K ohms. Digital meters that use very tiny measuring currents sometimes get wildly high and inconsistent results, while my old analog meter gets a steady, reasonable reading. The same thing goes for measuring field resistance via the slip rings in an alternator.

Champion recently went to the molded-in resistor. Maybe their troubles will go away.

I prefer the REM37BY plugs for any engine approved for them. They resist fouling far better.

Dan
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Lol.

I'll take high time bendex over new slicks any day. Also look into the price to repair. Ask any working pilot, slicks are crap, just read up on all the near new slicks that check out.
 
James331 said:
Lol.

I'll take high time bendex over new slicks any day. Also look into the price to repair. Ask any working pilot, slicks are crap, just read up on all the near new slicks that check out.
Click to expand...

I speak as an experienced full-time mechanic, looking after numerous airplanes with both Slicks and Bendixes, and as former Commercial pilot flying both types.

Dan
 
bnt83 said:
I have yet to fly behind Rotax, you might have to fix that :D
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I agree! I almost bought a nice 2006 rans courrier last summer but read that the 912 doesn't like 100 av gas and that the carbs need to be balanced a lot, etc. great airplane seems to me. Like to hear your views! I'm too old and too lazy to be hauling gas, etc.
 
Dan Thomas said:
I speak as an experienced full-time mechanic, looking after numerous airplanes with both Slicks and Bendixes, and as former Commercial pilot flying both types.

Dan
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I'm glad you've had better experiences with slicks than most.


So what do you charge to change the rotor on a slick vs a bendex?
 
James331 said:
I'm glad you've had better experiences with slicks than most.


So what do you charge to change the rotor on a slick vs a bendex?
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Depends on the installation. Some mags are far harder to get off and on again than others, and that is the biggest part of the cost. The Slick mag opens quickly, the distributor comes off in a minute and a new one bolts on in another couple of minutes.

The distributor is the least of the issues, in my experience, aside from the worn carbon brush problem that was the subject of an SB and was a result of faulty assembly at the factory. Points usually need changing at the second 500-hour inspection, the rest is OK. When I looked after a flight school fleet, I had no Slick mag issues that weren't related to factory problems like too much grease on the points cam (gets in the points), misaligned coil tabs (causes the brush wear), or one (and only one) worn distributor gear caused by the rotor gear not being pushed onto the shaft far enough, another factory problem. Champion now owns Slick and maybe they'll get a handle on quality control.

All of my flight-school Slicks went to TBO. Easily.

Slick's poor reputation came mostly from some really rotten magnetos 40 years ago, and the aforementioned SBs. But since most ADs arise out of SBs, a check of the Bendix SB history is enlightening.

Dan
 
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