For those of us that also maintain air cooled engines

[Anticept]

http://blog.aopa.org/opinionleaders/2015/03/19/champion-from-denial-to-acceptance/

I just saw this article, and I had already ordered tempest plugs last month, ready to start replacing our champion ones. We've been having a lot of problems with champion plugs, and it seems like I'm not the only one who has noticed. I just had 5 of the 8 champion plugs fail the spark test in the bomb tester (the pressurized test box), shooting sparks up out of the barrel. Took out the ohmmeter and those 5 were a couple hundred thousand ohms, with one being 1.2 million ohms. The lowest was just shy of 20k. Going to see how tempest holds up now.

I'd also recommend anyone using slick mags: next time you have to replace them, dump them. Bendix mags, while more expensive, are MUCH better built. Here on the field, a Diamond had the slick mags replaced with bendix, and are reporting a much easier starts for months now (by the way, Diamond tried to tell them that bendix mags aren't approved, which is a full on crock because the type certificate for the engine says they are, and the FAA agreed with us when it was escalated). There's a P210 Centurion here where the owner did the same and he too finds it's easier to start. Finally, bendix parts are cheaper than slick mags, which basically means you can maintain them on condition (bad wording, meant keeping up with routine points and condenser maint), and rebuild as necessary. Slick mags eventually get more expensive to maintain than buying new (if you price out rebuilding them, the parts costs are higher than a brand new one).

[Doug Hereford]

Anticept,

I think in general, I disagree with all of that. I strongly recommend the 500 hr. inspection and replacement of breaker points and capacitor for any Slick mag. In my experience, if that maintenance is done, our mags. routinely go to 3500 hrs. without unscheduled events. We also replace any spark plugs in training aircraft at 250 to 300 hrs. time in service regardless of test results and erosion. This is an agreed to standard between us in maintenance, the school.

I do agree with performing resistance checks on all spark plugs during scheduled inspections. Also, in my opinion, it is mandatory to bust all of the carbor out of the area around the center electrode at each inspection. To do this correctly requires a special tool that is not exactly cheap.

 

In general, keeping the secondary side in good shape will pay off in the long run on magneto mx.

 

Doug Hereford

[Anticept]

Sorry, perhaps I misworded. Routine maintenance should have been a better wording, as I do agree with the 500 hr maintenance. But, in general, I've not spoken with anyone who has had slick mags last anywhere near as long as bendix in my area, and this includes a lot of instructors at the A&P school that I attended.

[Doug Hereford]

I also think the whole Tempest spark plug thing is more hype than anything. I have never personally had big problems with Champion plugs as long as they are maintained.

Not to be nit picky, but none of us mechanics "rebuild" magnetos.

 

Doug Hereford

[Anticept]

That's the same thought I had for a while, but lately I've noticed I've had quite a few champion plugs that were fouling a LOT shortly after putting them in. We had been attributing it to people running too rich, when I decided to give tempest plugs a try so I ordered a box of them. This 100hr, I had sparks firing back up through the barrel (which I've seen a few times before as well) and I might have been nailed if I had my hands anywhere near them while firing the spark on several of the plugs. That's when I tried the ohm test and none of them were anywhere close to the spec sheet, even the two that I had put in less than a hundred hours ago.

 

I have a couple of others that also run shops around here, and they too have been seeing problems with champion plugs, but figured it was just the nature of the beast. The last guy I spoke with said he's been using tempest massive and fine wire plugs for a long time in the planes he works on, and doesn't recall having much trouble with them, even if they get worn down.

 

I had been seeing people recommending tempest around the net for a while now and thought the same about some of the tempest marketing, it sounds like a bunch of hype. But after this last inspection, and then finding that article, I'm giving them a try and see how it works out. Plus, the price point is pretty reasonable!

 

As for mags: there's one of my old instructors who worked at an engine overhaul shop. He never liked slick mags, and feels they are poorer build quality, and has quite a bit of experience working with both brands for many years. We've gone through the slick and bendix mags (taking apart and putting back together), manuals, and parts costs, and a lot of what I see supports his opinion on the two. With the DA-40 that switched from slick to bendix almost a year ago and have reported consistently easier starts (although it could just be confirmation bias), I suspect there may be merit to the claims. The same with this P210, he switched at my recommendation and is reporting easier starting and better engine operation (again, could be confirmation bias).

 

I really wanted to drop in fine wire on this warrior, but the owner doesn't want to front the costs right now, so we'll see if the tempest massives work out for a few hundred hours. I know that being all new plugs isn't a fair comparison until we're a couple hundred hours in, so I'll try to remember to report back.