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PMag Switches

rockitdoc

Well Known Member
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I would like to have the left and right PMag 'On' and 'Test' switches in one toggle switch each. I am going with a starter button instead of a key with left, right, both and start functions. The two switches would function having the first position, or down, 'Off' (no power to Pmag); the middle position 'On' (ship power to PMag); and the up position 'Momentary On' (ship power off, internal Pmag power on).

I have found many switches where the middle position is 'Off' with 'On' and momentary 'On' in up and down positions, but none appropriate for aircraft with an Off-On-(On) configuration.

Has anybody wired their system this way? What do you think of the idea?

S
 
I would like to have the left and right PMag 'On' and 'Test' switches in one toggle switch each. I am going with a starter button instead of a key with left, right, both and start functions. The two switches would function having the first position, or down, 'Off' (no power to Pmag); the middle position 'On' (ship power to PMag); and the up position 'Momentary On' (ship power off, internal Pmag power on).

I have found many switches where the middle position is 'Off' with 'On' and momentary 'On' in up and down positions, but none appropriate for aircraft with an Off-On-(On) configuration.

Has anybody wired their system this way? What do you think of the idea?

S

I like to keep it really simple for me and my customers, so I just install standard (locking usually) toggles for L/R ignition and breakers above those switches for the Pmags if they are using them. I think the 3 pos switches get confusing on exactly whats going on, takes too many brain cells.

With breakers is really obvious, pull the breakers and do a mag check.
 
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3 pos switch

I'm using the honeywell 3 position switches which work great, and are very high quality. One for each pmag.

https://vansairforce.net/community/showpost.php?p=1403570&postcount=55

Up is normal - pmags "active" and 12v to pmag
Middle is "pmag internal generator test" so pmags active with no 12v power
Down is off - no power and pmags grounded (inactive)

It's almost idiot-proof I think.

To do maintenance on the pmag I have another switch far on the other side of the panel that has an indicator light that shows the pmag has power for maintenance/timing.
 
I have 2 PMAG test toggle switches (Honeywell TL series) which are normally on and then momentary for the test position. That way they are normally on without me doing anything. I have a standard Cessna style rotary ignition/start switch.
 
Switches

I have 2 PMAG test toggle switches (Honeywell TL series) which are normally on and then momentary for the test position. That way they are normally on without me doing anything. I have a standard Cessna style rotary ignition/start switch.

Do you know the specific Honeywell switch part number?
Off-on-momentary?
 
1TL1-8F

Do you know the specific Honeywell switch part number?
Off-on-momentary?

Larry, I bought Honeywell 1TL1-8F switches for this purpose (with a rotary switch for main ignition/start). Technically they're an ON-(ON), just don't connect to the momentary ON terminal. They've got a locking detent so you've got to consciously pull out & up to test, once released (i.e. by default) the P-Mag is on.
 
My 8 is configured EXACTLY as you describe. Works great. Simple fast test of p lead and internal alternator function. 1800 RPM, right mag off (right switch down) tests right mag p lead. Temporarily push the left switch up killing power to the left pmag tests the right pmag internal alternator. Back to both (move right switch back to center on position) reverse the procedure for the pmag. Done in just a few seconds and simple.
 
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