keyed starter switch

[prkaye]

I want to use a starter switch with a key, like you see in production airplanes. Most of these have settings assuming 2 mags... OFF, MAG 1, MAG 2, BOTH, START. My engine has one mag and one lightspeed electronic ignition. How does this affect my choice of keyed starter switch? What have others done?

[vic syracuse]

You can use the (Gerdes?) switch from Aircraft Spruce. It is labled OFF/L/R/Both. The lightspeed wiring diagram will show you how to wire it appropriately. I have a mag on the left side, and Lightspeed Plasma III on the right, and the keyed switch works fine.

Vic

[dhall_polo]

Yes, LSE has a keyswitch option to use a standard keyswitch, and this option is depicted in LSE's wiring diagrams.

I am using a standard keyswitch with one mag and one LSE/direct crank. You feed the mag line from the keyswitch to an optional 'output' connector on the LSE control unit. This option makes the LSE work like a mag in that it will look for the keyswitch line to be grounded for off, and ungrounded for on.

On the input connector, you feed always hot power (across a 5A breaker\fuse).

[rv9av8tr]

On my Long-EZ I experienced a standard key switch failure such that it would not kill the LSE power. After that, I wouldn't trust the key being OFF to actually kill the engine. Lessons learned from the school of hard knocks.

On my RV-9A, I'm using separate toggle switches for the MAG and LSE, that way OFF is OFF and I can isolate them individually. I'm including a red diode on the hot side of the LSE power so I'll know the LSE is in fact OFF.

Then I'm using a Keyed switch to actually engage the starter solenoid circuit. That way, failure of a key switch doesn't prevent me from being able to start the engine by hand proping, if I were ever put in the position to need to do that.

You can see my schematics here: http://www.mykitlog.com/users/displa...og=63703&row=5

[vic syracuse]

Any switch can fail. I've seen both keyed switches and toggle switches fail to perform their designated function. I usually try to check the ignition systems for grounding prior to landing on the downwind while at low power settings, or right before shutdown if I happen to forget.

Vic

[rv9av8tr]

Well... as we said in nuclear power, expect any failure at any time!
I had lots of switches in the LEZ.... but never had a failure in 22 yrs. Two mag key switch failures in same time though indicates a "trend" for me. Just expressing my personal experience on switch reliability... a real world observation, take it for what it's worth............

[Jimd]

I agree with Vic and I teach all my students to pull the key and put it on the glare shield at shut down. This gives everyone (me, them, line guys, a&p) a good way to see that the mags are off. It is a good way to develop a habit of ALWAYS getting the mags off. It is my belief and practice that if you do a normal mag check at run-up you have tested the switch. I also test the switch as Vic suggests occasionally.

When I clean the prop I can see the key on the glare shield and know the mags are off.

[n815vp]

I used the ACS A-510-5 with "off" ,"R"."L","BOTH",and "START". The "R" is connected to the Lightspeed ignition WITH a circuitbreaker,(mounted next to the key switch) ,between the switch and LSE. If it were necessary to operate only on the Mag. you would just turn the key switch to "L".
the circuitbreaker on the LSE side allows you to disconnect all power to the LSE unit.You could use a switch in place of the breaker.
Also, the switch is wired to use both MAG and LSE for starting.

[vic syracuse]

Jim is right on. I pull the key upon shut down, and lay it on the glareshield. I never touch the prop without looking for the keys first.
I had an incident about 20 years ago that still gives me the willies. A very dear friend of mine was scratch building a thorp T-18. The owrkmanship was absolutely perfect, and he had spent about 15 years on it. He finally hung the engine and ran it, and was so proud of it. He invited me over to see it. Keep in mind I was much younger, and he was much older (67 I believe) and somewhat a mentor. I had brought my 2 boys with me, and Lou says "come here and feel this compression." He had procurred the engine from a wrecked Piper Colt years earlier. Anyway, I pulled on the prop without thinking, just very slowly to feel the compression, NOT to start it. I will never forget the sound as I heard the impulse mag fire and then the engine was running. That happened much faster than I can even write it here. I had hand started many engines by this time, so my hands luckily were not wrapped around the blade, and as soon as I heard the impulse mag fire it was probably a natural reaction that I pulled my hands back. I had nightmares for weeks, and my boys eyes were wide as saucers! Lou was absolutey shocked.

What we learned, and I have been extremely cautious ever since, is that there is a time when our projects go from being a project to being an airplane, even while they are still in the shop. The time comes when we have to treat them as airplanes, with all of the commensurate safety practices. I know that once I have power and/or an engine on the airplane, otheres are not allowed to sit and play any more. It's too easy to get hurt.

Vic

[rv9av8tr]

AMEN!!!!!!!!!!