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It is interesting with all of the conflicting data regarding the impulse mags on some of the engines we use on the RV-10. The gentleman (Joe) in the Slick booth at OSH was quite outspoken that they need to come off due to the potential for a catastrophic failure. However, some of the engine shops were not so adamant. Not knowing who to believe, and not wanting to be the one to find out, I replaced the 6351 impulse mag on my IO-540 with a 6350 straight mag, and now start only on the Lightspeed electronic ignition. I've actually not noticed any difference in starting.
If you have switches on the ignition it is easy to do this---just enable one ignition for starting. And don't forget to turn the other ignition on after starting! If you have a key switch, don't forget to install a jumper on the key switch to disable the non-impulse mag for starting, otherwise you will get a kickback, especially if you are using the Lithium batteries which spin the starter quite rapidly. Vic |
I am thinking of replacing the Slick mag with one of these.
http://www.surefly.net/ I would like to see a few more field reports before I go down the surefly road. Vic's idea is also being considered especially since I have toggle switches installed for my one Slick and one LSE ignition. |
More info after the engine shop spoke to the Lycoming people. When a three blade prop is hung on this engine series, the harmonics change at the rear of the engine. This causes an unusual wear on the mag parts, which can eventually cause a failure with the rivet in the impulse assembly. Some issues have also occurred with the mag due to engine mods. My engine guy said he has not personally came across the mag failure issue, but has heard about it from other shops. I agree with Vic, there is nothing wrong with the Slick non-impulse mags, I went with the Bendix impulse mags vs the Slick Start unit. Its all about what you want to start the engine. Once the engine is running, a mag is a mag. As Vic said, I don't want to be the one to find out. Under Murphy's Law, I would be the one to have a castitrophic failure with the Slick impulse mag set up.
P.S. No expertise in this area, just passing on the info I was told. |
Approved Slick Models
For future reference for anyone that does a thread search on this topic, IAW with Lycoming SI 1443K, the only approved Slick mags for an IO-540-C4B5 or D4A5 (the 2 most prevalent 540 models on RV-10s) are the 6393 retard breaker mag on the left, and the 6350 plain mag on the right.
http://www.lycoming.com/Portals/0/te...20Magnetos.pdf |
Been running a NON-Impulse S-20 on the right side location along with a Lightspeed ignition.
The ignition is configured to use the Lightspeed for starting then bring the Bendix online after running. Works good now for over 1000 hrs with no impulse coupler to fail. |
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Vic Vic |
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More info after the engine shop spoke to the Lycoming people. When a three blade prop is hung on this engine series, the harmonics change at the rear of the engine. This causes an unusual wear on the mag parts, which can eventually cause a failure with the rivet in the impulse assembly. Some issues have also occurred with the mag due to engine mods. My engine guy said he has not personally came across the mag failure issue, but has heard about it from other shops. I agree with Vic, there is nothing wrong with the Slick non-impulse mags, I went with the Bendix impulse mags vs the Slick Start unit. Its all about what you want to start the engine. Once the engine is running, a mag is a mag. As Vic said, I don't want to be the one to find out. Under Murphy's Law, I would be the one to have a castitrophic failure with the Slick impulse mag set up.
P.S. No expertise in this area, just passing on the info I was told. |
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The only reason Lycoming switched to Slick is that they are owned by Textron, and Bendix is owned by Teledyne and they weren't going to buy from their corporate competitor. Same reason Cessna switched from Continental engines to Lycoming. |
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