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-   -   LANDING CHECKLIST PMAG EXTERNAL POWER ON (https://vansairforce.net/community/showthread.php?t=171381)

BMW_X6M 05-09-2019 06:11 PM

LANDING CHECKLIST PMAG EXTERNAL POWER ON
 
If you are running dual PMAG's or any kind of all electronic ignition your landing checklist should include the PMAG external power verified ON.

GUMPS check when you get to Switches would be a good time to verify that the external power is ON prior to the engine RPM getting low for landing. Remember the PMAG runs on internal power until the RPM gets too low, and then it switches to EXTERNAL POWER or DIES if the power is OFF.

I have connected both PMAG external power circuits to the Dynon EFIS which monitors the voltage and produces an aural and visual alarm if it is OFF.

ty1295 05-09-2019 06:49 PM

Quote:

Originally Posted by BMW_X6M (Post 1345462)

I have connected both PMAG external power circuits to the Dynon EFIS which monitors the voltage and produces an aural and visual alarm if it is OFF.

I assume you used one of the extra inputs to do this. Did you then change the configuration inside Dynon to tell it that it was a voltage monitor and what it was for so the screen displayed that info?

Icarus 05-09-2019 06:50 PM

How would one successfully start a dual pmag setup without at least one mag powered? Do you routinely turn power off to one or more p mags in flight? I love checks as much as the next guy, but this seems a bit excessive.

Maybe I'm missing something, my wife would say that's pretty common...

Bavafa 05-09-2019 09:31 PM

I have a miniature toggle switch for the PMAG power. They can easily be flipped to the off position by mistake, if your hand accidently hit them. For that reason, I have installed a LED that will come on if the power is turned off. That is for my sanity check.

BMW_X6M 05-10-2019 01:40 AM

Quote:

Originally Posted by ty1295 (Post 1345472)
I assume you used one of the extra inputs to do this. Did you then change the configuration inside Dynon to tell it that it was a voltage monitor and what it was for so the screen displayed that info?

Actually I described it incorrectly. DYNON is looking for a ground on the contact inputs, so I used two small relays. When de-energized they produce the ground for the contact inputs. The screen shows indicator lights.

KRviator 05-10-2019 05:11 AM

Quote:

Originally Posted by BMW_X6M (Post 1345521)
Actually I described it incorrectly. DYNON is looking for a ground on the contact inputs, so I used two small relays. When de-energized they produce the ground for the contact inputs. The screen shows indicator lights.

Not necessarily. It depends how you configure your color ranges.

I connected two inputs to the Pmag power inputs at the PMag itself. 0-4.5V = Red (Problem). 4.5V-5.0V = Green(OK). You can put 14V into a 5V input without damaging the EMS module, according to Dynon.

According to EMagAir, you supposedly cannot measure PMag internal voltage with an external voltmeter when the PMag is running because it is diode-isolated, but the Dynon doesn't lie. I can turn ships power off to the PMags in flight and the Dynon reports >4.5V on the PMag power pin. I am guessing it is similar to the VP-X installation manual caution, that notes you will observe close-to-bus voltage on a VP-X power pin that is "OFF" if measured with a voltmeter, but apply any kind of load, and it will show 0V.


EDIT: Apologies, BMW, you clearly stated contact inputs. I used GP inputs for my PMag power inputs.

SuperCubDriver 05-10-2019 12:21 PM

I once forgot to switch Ign Pwr back on after runup and didn?t read my T/O checklist thorough enough. So after a normal flight the engine stopped on rollout after landing.
I have Ign Pwr in the T/O checklist and Abnormal Checklist. May be a warning light is a good idea as well.

engineerorange 05-10-2019 01:57 PM

monemtary switches
 
I just used a 3 position switch, bottom: grounded and powered, center:ungrounded and powered, and top:momentary ungrounded and unpowered. Can't stay in the momentary position unless you hold it there

Jeff A 05-10-2019 04:18 PM

Quote:

Originally Posted by engineerorange (Post 1345660)
I just used a 3 position switch, bottom: grounded and powered, center:ungrounded and powered, and top:momentary ungrounded and unpowered. Can't stay in the momentary position unless you hold it there

Same here. 600+ hours with this setup.

Scott Hersha 05-10-2019 05:13 PM

Mine is exactly like engineerorange too. Both Pmags powered through pullable circuit breakers, which stay in unless I?m checking them a couple times per year. I check the momentary position (ships power off) on every takeoff when above 1000 RPM. If ships power failed in flight, I wouldn?t know it until I turned off the runway and RPM dropped below about 750 RPM.


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