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Thread: Key Ignition vs. Toggle Switches

  1. #21
    Senior Member av8rps's Avatar
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    Default Re: Key Ignition vs. Toggle Switches

    Quote Originally Posted by jtpitkin06 View Post
    The discussion of the ACS switch ....snip.... He had experienced an ignition switch failure and replaced it with toggles. Did he still have the bad ACS switch? Yes!..snip...
    John Pitkin
    John,

    That is an EXCELLENT post! And it makes perfect sense with what has been happening. Thank you for sharing that information. I am going to share it with my friends as we all wondered why the problem was happening. Now we know.

  2. #22
    Senior Member Dorsal's Avatar
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    Default Re: Key Ignition vs. Toggle Switches

    Quote Originally Posted by szicree View Post
    Good stuff, John. I built my RV-4 with toggles and a pushbutton (and a diode), figuring that a motivated thief could easily get past the key switch anyway.
    More than once I have boosted some big eyed kid into the pilots seat after seeing them watch from the fence. It always puts a big smile on their face (and the grateful parents) but only if I have the key in my pocket.
    Dorsal ~~^~~
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  3. #23
    Senior Member Esser's Avatar
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    Default Re: Key Ignition vs. Toggle Switches

    Quote Originally Posted by szicree View Post
    Good stuff, John. I built my RV-4 with toggles and a pushbutton (and a diode), figuring that a motivated thief could easily get past the key switch anyway. It occurs to me now that the propellor of an unattended plane with only a pushbutton poses a potentially lethal risk should some bonehead reach in and start pushing buttons. I know it's unlikely, but if some idiot accidentally chops his friend to bits with my prop I know exactly who'll get sued . I think this build will have a keyed switch somewhere in the system.
    Simplest fix for wanting a key some where is if you have easy access to your battery put on a locking master switch on your battery.

  4. #24
    Senior Member Dave S's Avatar
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    Default Re: Key Ignition vs. Toggle Switches

    John P - Regarding the photos of the burned contacts

    Were you able to determine exactly what kind of metal the contacts are made of? Almost looks like aluminum??? I know photos often don't show the colors well; but, on the photos of the contacts they certainly don't look like copper, brass or gold to me.

    Also - was there any type of lubricant on the contacts when it was originally opened up?

    Thanks,

    Dave S

  5. #25
    Senior Member jtpitkin06's Avatar
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    Default Re: Key Ignition vs. Toggle Switches

    The contacts in the ACS switch appear to be silver plated brass. The switch shown is notable in that it is one of the later manufacture dates with the identifying red paint in the screw heads. It is not subject to the AD for periodic lubrication but it did have lube inside.

    I have the same switch in my Cessna. It too is a later model and I have a diode in the start circuit. The AD requires that I check the switch is functional in the OFF position. I may open the Cessna switch on the next annual just to have a peek at the contacts.


    John Pitkin

  6. #26
    Senior Member jrevens's Avatar
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    Default Re: Key Ignition vs. Toggle Switches

    A recent series of conversations with a friend & fellow builder, have brought this issue to mind again. I'm probably just beating a dead horse at this point, but I have a couple of thoughts/theories on this subject that I'd like to share with the group.

    Regarding the possibility of these ACS keyed switches somehow causing the failure of a sensitive ignition module - since these switching contacts are located in the same enclosure & relatively close to each other, I wonder if there is a possibility of the high voltage back emf, produced when a non-diode protected starter solenoid coil is de-energized, "jumping" the gap or perhaps following a slightly conductive "trace" (caused by previous arcing) from the starter coil contact to one of the ignition contacts, effectively "zapping" an ignition module.

    The second thing I'd like to present is that having a switch with a high enough current & voltage rating does not always make it an ideal choice for a low voltage, low current application (such as, perhaps, an ignition grounding switch). It is fairly common to have cadmium-silver plated contacts on high quality switches, and these contacts are sometimes not recommended for use with low voltage &/or current. The reason is because there is not enough (or any) arcing that occurs during use, and some arcing has been found to be desirable or necessary to keep these contacts from slightly oxidizing & creating an abnormal amount of resistance when "closed". This is probably not the case with the ACS switches, since they have a sliding contact action... I don't know.

    I'm using a small key switch for start, & 2 toggle switches for ignition (similar to the way that Van's does it with the RV-12) on my Kitfox.
    John Evens
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  7. #27
    Senior Member GWright6970's Avatar
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    Default Re: Key Ignition vs. Toggle Switches

    Quote Originally Posted by jiott View Post
    Could someone post a simple wiring sketch for the setup with toggle for mags and keyswitch for starting. This is probably a dumb question, but I am not very confident in electrical issues and need to start learning real soon since my panel build is coming up.

    Jim
    I wish to second Jim's request!

    It would be awesome for us NON-ELECTRICAL TYPES to have a diagram showing how to incorporate the two toggle switches into the Kitfox factory diagram using the ACS switch!

    I am particularly interested in how and where the shields of the two ignition wires are grounded in such an installation.

    HUGE THANK YOU!
    Grover
    Grover Wright
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  8. #28
    Super Moderator Av8r3400's Avatar
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    Default Re: Key Ignition vs. Toggle Switches

    I'm a little confused by the shielding part of your question.

    The brown wire from each module is what is switched (to ground) to turn off the ignition module. From what I can see in the books, these are not shielded wires.
    Av8r3400
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  9. #29
    Senior Member jrevens's Avatar
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    Default Re: Key Ignition vs. Toggle Switches

    Hi Grover,

    I think you'd find a lot of useful information about this in the "AeroElectric Connection" by Bob Nuckolls, if you haven't already looked at that. I'll try to explain how he has suggested wiring that circuit. It's probably the simplest circuit on the airplane, so my long explanation will probably be over-kill. You can use single-conductor shielded wire for each ignition module. 16 or 18 gauge would be fine. I used 18 gauge. While shielding isn't necessary on these circuits, and even 18 gauge is bigger than it needs to be, that type/size of wire was suggested for robustness, as well as being able to cleverly use the shielding as the ground conductor. So, a pigtail is attached to the shield on each wire, and each pigtail goes to it's respective common terminal on an ignition switch (toggle, rocker or whatever). Each center conductor attaches to the N.C. terminal of it's switch. At the ignition module on the engine, the center conductors of those 2 shielded wires each goes to it's respective pin on the module connectors (the brown wire mentioned by Larry - refer to Rotax manual). The shields from your 2 wires are then connected to a grounding point ON THE ENGINE, again with pigtails. So, when a switch is "off", contact is made between the common and N.C. terminals, which connects the ignition module pin, through the center conductor to the switch and from there through the shield back to ground at the engine. When a switch is "on", that pin is disconnected from ground as the N.C. contact becomes "open". Again, you don't have to use a single conductor shielded cable - you could use a 2-conductor un-shielded cable for each module (or other combinations of conductors with or without shielding if you wanted to), but the shielded cable is generally a little tougher and more resistant to intolerable damage. It's a nice, clean way to do it, and you've also got shielding, whether it's needed or not.
    Last edited by jrevens; 12-01-2017 at 08:57 PM.
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE
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  10. #30

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    Default Re: Key Ignition vs. Toggle Switches

    You can run a very simple on-off-start ignition switch when using toggles for the ignition boxes.

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