Slick Magneto Failures

[chuckwn]

Ignition System Failures:

The 1535 hour life of my RV-8 has now seen two ignition failures. Both of these were failures of Slick Magnetos purchased brand new when the plane was constructed. Note that my RV has been equipped with one Lightspeed ignition and one Slick magneto for the last 1400 hours.

The first failure occurred at around 1000 hours in the form of a magneto coil failure. Of course one discovers this during a magneto check and away from one's home airport. This was resolved by installing the mag I had removed for the Lightspeed installation and replacing the failed magneto.

The next failure was the a condenser failure. This happened on the magneto that had only 500 hours since new. I was able to repair this by stealing the condenser from the mag with the dead coil.

At this point, I was so distrustful of Slick mags that I flew around with a spare slick mag with the proper gear bolted on. I also carried a magneto timer and appropriate tools for a field repair.

One only has to look at the parts prices for Slick mag parts to see that the failure of a coil ($278) is nearly half the price of a new magneto and a condenser at $108 is outrageous. Further research reveals that Bendix magneto parts are priced at roughly 1/3 of Slick prices (Coil $98, Condenser $21).

After more discussion, I decided to switch to a Bendix magneto for three reasons.

1) Cheaper parts
2) More reliable (Hopefully)
3) Hotter Spark

Bendix mag's can be obtained from aircraft savage yards for very reasonable prices. One nifty option I also employed is conversion to an automotive ignition harness and plugs using guidance from G3i's website:

Magneto Ignition Harness Conversion to 8.5mm Super Conductor Automotive Spark Plug Ignition Wires:

Bendix Series 4 & 6cyl. Magnetos

Slick Series 4 & 6cyl. Magnetos

 

[rocketbob]

not only that

Bendix mags are easier to work on because they can be completely disassembled with ordinary hand tools. Slick mags are easy to work on also, but you need the T-100 toolkit which I think I gave $300 for. So if you wanted to replace the rotor in a Slick you need a special puller. On a Bendix the rotor comes out when you split the mag. The E-gap is a little bit easier to set on a Slick, you need a $60 pointer tool to set it on the Bendix. I've seen a few Slicks pretty crispy inside from the infamous bad carbon brush problem. 1100 hours+ with my Bendix mag and I've never had any issues other than doing the normal 500 hour checks.

 

[petercavallo]

SAme situiation

Hi Chuck,
Any maintence issues on the LSE ? I was thinking to go to 2 LSE's when my supply of mags run out instead of rebuilding them

Peter
RV6.2

 

[mannanj]

Slick

As my good buddy says---I'd rather have one marginal Bendix than two "good" Slicks.

 

[DanH]

Here's an interesting Slick failure.

Run-up and inflight performance was perfectly normal. Recently it seemed like hot starts were becoming more difficult, but that could be several things. The interesting symptom was an infrequent, random RPM alarm from my GRT EIS/EFIS; just a second or two reporting some crazy high RPM. I thought about it and concluded there were random electrons loose inside the left mag, as the GRT would count any voltage rise followed by a drop to zero as a point opening. Annual time, so both mags came off for a look. TTSN = 315 hours.

The right mag was normal, but the left contained a huge load of what looked like fine fuzzy dust:

Didn't take long to spot the problem. Check out the rotor gear. It's rubbing against the underside of the overhanging distributor block. And the top corner of every tooth is worn away where it was pushing up into the body of the mating distributor gear:

The rotor gear is simply pressed on. The distributor block wouldn't allow it to come off unless something fractures, thus no outright failure...at least not yet.

There was a second failure. The rotor finger is loose and looks like it was hot. This is a rejection item per the Slick manual. Is it related to the gear failure and all the loose plastic dust circulating in the mag? I dunno. Doesn't matter I guess; the distributor gear must be replaced anyway, as it is badly worn by the rotor gear. You can see the thin spots where the rotor teeth will soon wear all the way through:

 

[jetdriven]

Our shop has seen 3 Slick magneto failures this past week. All were Lycomings, the left mag, and 2, at least, were the coil. All were around 300 hours since the last inspection.

I pulled the two Slick mags off our factory OH engine at 89 hours, and sold them to a VAF member. I used those proceeds to fund the Bendix 1200s that went on.

Of course, luck would have it, 8 hours later, on a long trip, one Bendix failed. The points were not opening, the felt crushed down or something and they werent opening. And they weren't parallel. Kelly rebuilds.

 

[Russ McCutcheon]

Here's an interesting Slick failure.

Run-up and inflight performance was perfectly normal. Recently it seemed like hot starts were becoming more difficult, but that could be several things. The interesting symptom was an infrequent, random RPM alarm from my GRT EIS/EFIS; just a second or two reporting some crazy high RPM. I thought about it and concluded there were random electrons loose inside the left mag, as the GRT would count any voltage rise followed by a drop to zero as a point opening. Annual time, so both mags came off for a look. TTSN = 315 hours.

The right mag was normal, but the left contained a huge load of what looked like fine fuzzy dust:

Didn't take long to spot the problem. Check out the rotor gear. It's rubbing against the underside of the overhanging distributor block. And the top corner of every tooth is worn away where it was pushing up into the body of the mating distributor gear:

The rotor gear is simply pressed on. The distributor block wouldn't allow it to come off unless something fractures, thus no outright failure...at least not yet.

There was a second failure. The rotor finger is loose and looks like it was hot. This is a rejection item per the Slick manual. Is it related to the gear failure and all the loose plastic dust circulating in the mag? I dunno. Doesn't matter I guess; the distributor gear must be replaced anyway, as it is badly worn by the rotor gear. You can see the thin spots where the rotor teeth will soon wear all the way through:

I had the same thing happen in July of 2012, the rotor gear slid up the shaft and made a mess just like yours, I talked about it hear then but your pictures make your post a lot nicer.

I replaced the rotor gear in both mags with new ones, there?s no sign of trouble yet in 150 hours.