ACS Keyed Ignition

[gammaxy]

Are there any "gotchas" to using the Aircraft Spruce keyed ignition http://www.aircraftspruce.com/catalog/elpages/igswitches.php with the Aerovee? I have a vague memory of someone mentioning a problem with this, but I can't find the problem on any of the forums.

[falvarez]

My understanding is that the "gotcha" is that the Mags must be grounded separately...in a non-keyed setup, this means using a Double-Pole switch (or two separate switches).

[kmacht]

It can be used but it requires two heavy diodes and a relay. On the aerovee the mags can not have their ground wires connected otherwise they ground each other out and you get a engine that runs but runs badly. What I did was to put a diode on the ground lead coming off of each mag and then tied both wires together at the switch. This makes it so each mag gets grounded out when the switch gets turned off but when it is on the mags don't ground each other out. If your not familiar with them a diode only allows current to flow one way through it. The relay is so you can use the secondary electronic ignition with the switch. The switch is designed so that when off it grounds the switch terminal. When you turn the key to a mag on position it opens the ground. You need to install a relay between the switch so that when it sees ground it is open and when it doesn't it closes. I bought my relay from b&c aircraft electric and the diodes from digikey.com. It really isn't that hard to do but if you aren't familiar with electronics I would suggest just going with the sonex recommended 2 switches. One needs to be a double pole single throw switch for the main mags and the other a single pole single throw switch for the secondary electric ignition. The acs key switch frees up a bunch of panel space but also adds a lot of complexity to a otherwise simple system.

Keith
#554

[gammaxy]

Thanks. Your answers clued me into the section in the Aerovee manual where the magnetron ignition is described and now I remember why the keyed ignition would not be straight forward.

I considered building a small pcb with solid state SPST and DPST relays to make it work, but don't want to add customized complexity to the system.

While I'd like to save panel space, my real intent is to reduce the likelihood of my kids accidentally spinning the prop or starting the engine. What do you think about a keyed master switch? I like the idea because it will make it less likely for me to drain the battery (or I'll at least be able to check my pocket for the keys when I panic that the lights are still on). I haven't found anyone else with one, so I don't know if there is a safety issue I'm not thinking of. It won't save panel space (unless the key has a third position for the starter, but that seems dodgy).

[daleandee]

*

[kmacht]

Why not just install a keyed starter switch and leave the rest of the ignition stock? Most auto stores sell keyed starter switches

Keith

[8pointroll]

These postings regarding wiring an ACS ignition switch could not have come at a more opportune time for me because I have been scratching my head on how to do it properly. I understand the comments but would appreciate it if any of you who have installed the ACS ignition switch could take a few minutes to provide some additional clarification. I specifically would like to know which diodes and relay to use, the proper orientation for the diodes and how to wire the relay and diodes to the switch. My switch has the starter position as well.

Also, did any of you route any of your wiring through what I think are ferrite cores to eliminate interference and if so, what wires, what cores and how is it done.

Thank you all in advance for your time and assistance.

Best,

Stuart Leibovitz
781-985-2775
Sonex 1106, aerovee, tri gear, D180, AP, electric flaps, aerovee disc brakes, homemade smoke, cabin heat, canopy lift strut, horizontal split cowling, 90% done 80% to go

[kmacht]

I have a wiring diagram showing the setup on my computer at work. I'll see if I can dig it up and send you a copy when I get back on Monday.

Keith

[dcstrng]

My understanding is that the "gotcha" is that the Mags must be grounded separately...

GP has both types of ignition switches: http://www.greatplainsas.com/scelectrical.html

But still need to switch between them; I suppose an additional issue can arise when one has both magneto and some variation of conventional ignition…

Anyway… hmmmm...

[Bryan Cotton]

Many of the airplanes I have flown have two mag switches. I plan to do the same thing. For redundancy at a fly in or if I was letting kids/non-pilots sit in the airplane I would pull breakers for the starter and ignition.