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Q-talk 127 - Electronic Ignition System Installation

The editor of Q-talk said he was willing to pay me the big bucks if I would describe my dual EIS installation on my TriQ-200. Needing to pay off my Q's recent extreme makeover, I reluctantly accepted.

This is not a dissertation on the value of an EIS, whose EIS is the best or the advantages and pitfalls of dual EIS's vs. one EIS and one Mag. The objective is to simply describe my implementation.

This is the second dual EIS configuration I have flown behind. It all started with my Revmaster (a moment of silence, please).

I quickly concluded that I wasn't going to enjoy pulling the engine every annual to check the mags. My other dislike was that while it had dual Bendix mags, I really didn't have a redundant ignition system since both mags were in one case with a common drive shaft to the engine crankshaft - a single failure point.

Because of the Siamese mag configuration, I would still be carrying the weight of two mags even if I did replace one mag with a single EIS. So I decided to make the jump of faith to dual EIS's.

I chose Jeff Rose's EIS system and was completely satisfied. The installation was not complicated and they never gave me any problems. So when it came time to ceremoniously junk the Revmaster, I salvaged my ignition system and installed it on the O-200. Again, the installation was straight forward and the operation faultless (knock-on-wood).

Besides the physical installation, the other critical component is the electrical installation. Of course, the key to safety when hanging your bacon off of dual electronic ignitions is to have plenty of backup battery power. That is why it is strongly recommended that a dual EIS implementation include dual batteries.

And it's mandatory that the EIS by-pass the bus and wired directly to each battery. (In most circles it would be considered bad form to switch off the master switch because of an electrical problem and simultaneously kill the ignition.). Just remember, if you forget to turn off your ignition switch(es), your engine is still "hot". Turning off the master switch(es) doesn't do it.The illustration below shows how I addressed these issues. As you can see, it's pretty basic,(which usually means I missed something).


An important consideration is your choice of batteries. Guru Bob Nuckolls suggests that you use identical batteries and switch one out at each annual. That way you know you always have a fresh battery on board. I selected two Odyssey 14amp PC680's. They are heavy at about 15lbs each, but heck, I can already out run Sam so why tradeoff safety for more speed.

The next consideration is where to mount the batteries. Since they are heavy, they have significant influence on CG. On the Revmaster, I got away with mounting both of them on the canard, one on each side by the outboard fuselage shell. They were so handy there and cabling was short. However, the added weight of the O-200 required me to move one of them to the baggage area.

You can order a printed copy of Q-talk #127 by using the Q-talk Back Issue Order Page.