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prkaye

Well Known Member
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?
 
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
 
LSE has a diagram for this.

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).
 
I don't trust the key switches....

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/display_log.php?user=n539rv&project=161&category=0&log=63703&row=5
 
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
 
Expect failure at any time....

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............
 
And..

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.
 
key switch

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.
 
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
 
CAUTION!!!!!

vic syracuse said:
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.
Click to expand...
Don't depend on this method. I have seen worn switches where the key would come out in the "left mag" position. I saw a Globe Swift actually start with the keys laying on the glareshield.
 
Jimd said:
It is my belief and practice that if you do a normal mag check at run-up you have tested the switch.
Click to expand...

Not necessarily. You have not tested the "off" position. I've seen many switches that worked normally in the left and right positions but failed in the off position.
If you use a key type switch the "off" position should be tested regularly at idle power.
 
That's true...

vic syracuse said:
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
Click to expand...

...but there have been many more ADs and SBs issued against the aircraft type keyed rotary ignition switches than against good quality Mil-Spec toggle switches...:)

This is one location where you want the "good stuff", especially if it's connected to an EI system.

Take a rotary switch apart some day....:)
 
Resurrecting an old thread, but with a twist...

I plan on toggle switches for left and right mag, and a starter button (but read ahead). I *ALSO* want some sort of keyed switch "interlock" so that there's no way the engine can start without the key in and turned to "on". I could go with:
L/R Mags - toggle switches; Starter button; keyed interlock
or
L/R Mags - toggle switches; Keyed Off-On-(On) combination interlock and starter

Any suggestions for a good, high quality keyed switch or switches?

(And no, I do not want to rehash toggles vs. rotaries for mags, etc....this is what I want, and I just want some leads and advice on top quality keyed switches LOL!).

TIA!

Steve
 
Flying Scotsman said:
Resurrecting an old thread, but with a twist...

I plan on toggle switches for left and right mag, and a starter button (but read ahead). I *ALSO* want some sort of keyed switch "interlock" so that there's no way the engine can start without the key in and turned to "on". I could go with:
L/R Mags - toggle switches; Starter button; keyed interlock
or
L/R Mags - toggle switches; Keyed Off-On-(On) combination interlock and starter

Any suggestions for a good, high quality keyed switch or switches?

(And no, I do not want to rehash toggles vs. rotaries for mags, etc....this is what I want, and I just want some leads and advice on top quality keyed switches LOL!).

TIA!

Steve
Click to expand...

Why not install your switches in a locked compartment. When the compartment is closed and locked, the switches would be in the SHUT OFF position. All of your mag and start switches will be out of sight and you can use a quality latch lock instead of a electric switch lock.
 
gasman said:
Why not install your switches in a locked compartment. When the compartment is closed and locked, the switches would be in the SHUT OFF position. All of your mag and start switches will be out of sight and you can use a quality latch lock instead of a electric switch lock.
Click to expand...

Nah...that doesn't appeal to me. Interesting idea, but not what I'm after.
 
gasman said:
Problem with using a key switch to apply power to your starter button is if a mag switch is left on, you have a hot prop that can fire with little movement.
Click to expand...

That situation is irrelevant to what type of switch is used to supply power to the starter - that's an issue of leaving the mag switch hot. You will have this possibility any time you have a toggle switch for mags, regardless of the rest of the system.
 
airguy said:
That situation is irrelevant to what type of switch is used to supply power to the starter - that's an issue of leaving the mag switch hot. You will have this possibility any time you have a toggle switch for mags, regardless of the rest of the system.
Click to expand...

That is a given............ The point I was trying to make is the key switch that he wants to install will only keep the starter button from being hot when the master is on. It won't do anything to secure the aircraft, or make it safer.

This is what Steve said................I plan on toggle switches for left and right mag, and a starter button (but read ahead). I *ALSO* want some sort of keyed switch "interlock" so that there's no way the engine can start without the key in and turned to "on". I could go with:
L/R Mags - toggle switches; Starter button; keyed interlock or L/R Mags - toggle switches; Keyed Off-On-(On) combination interlock and starter. Any suggestions for a good, high quality keyed switch or switches?


My Piper had a hot mag with the key switch in the off position and the key in my pocket.............. Two years later came an AD.
 
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gasman said:
That is a given............ The point I was trying to make is the key switch that he wants to install will only keep the starter button from being hot when the master is on. It won't do anything to secure the aircraft, or make it safer.

This is what Steve said................I plan on toggle switches for left and right mag, and a starter button (but read ahead). I *ALSO* want some sort of keyed switch "interlock" so that there's no way the engine can start without the key in and turned to "on". I could go with:
L/R Mags - toggle switches; Starter button; keyed interlock or L/R Mags - toggle switches; Keyed Off-On-(On) combination interlock and starter. Any suggestions for a good, high quality keyed switch or switches?


My Piper had a hot mag with the key switch in the off position and the key in my pocket.............. Two years later came an AD.
Click to expand...

Well, it will make it safer in one sense...someone in the cockpit can't start the engine without having the key (interlock) in place, so some goober futzing around in the cockpit can't *accidentally* hit the start switch and have the prop swing. True, if the mags are hot, and someone turns the *prop*, it can fire...so do I hear a solution for that? Wire both mags to a switch so that when "Off", they're grounded (a la Pipers and Cessnas), effectively moving the "L"-"R"-"Both" positions of the switch off of the switch and onto two toggles? I guess that would mean an ON-ON-(ON) switch, then, right, with the first ON connecting the mags to ground, the rest as above?

(ETA: The purpose here is not to secure the aircraft from theft, or prevent entry into the aircraft...merely to "safe" the engine/prop from inadvertently swinging due to button presses...)
 
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Flying Scotsman said:
...The purpose here is not to secure the aircraft from theft, or prevent entry into the aircraft...merely to "safe" the engine/prop from inadvertently swinging due to button presses...)
Click to expand...

The ground operation may be safer, but you have just introduced another failure mode in the ignition system. The primary safety concern is in the air - ground handling/security is a distant second. I'd think that if you want to be safe on the ground, simply lock the hangar door.
 
Toobuilder said:
The ground operation may be safer, but you have just introduced another failure mode in the ignition system. The primary safety concern is in the air - ground handling/security is a distant second. I'd think that if you want to be safe on the ground, simply lock the hangar door.
Click to expand...

This would be a minor failure mode do to the fact that you are locking out only the starter button. Not an in flight issue. And you can still reach behind the panel and jump the rear of the switch with a coin.

Steve, I understand your issues now. Your local NAPA auto parts will have a quality key switch that will work for you. Take the extra key and tape it to the cargo floor under the carpet.............;)
 
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