I have no idea what the actual failure rate of a Pmag is. I don’t know if the bearing issue discovered during routine maintenance is a considered a failure. They are certainly more maintenance intensive than a mag.
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EMag issue
- Thread starter YellaDawg
- Start date
I have no idea what the actual failure rate of a Pmag is. I don’t know if the bearing issue discovered during routine maintenance is a considered a failure. They are certainly more maintenance intensive than a mag.
Toobuilder
Well Known Member
Just looking for clarity on your last post because its not apparent in my pea brain
I guess I'm in the minority. I check the internal alternators on every run-up.
My fingers are already on the switches, so why not perform the test?
My fingers are already on the switches, so why not perform the test?
I’m not necessarily a Pmag advocate. I used one with a regular mag largely based on hype. I find the 100 hour inspection invasive. The attraction of the auto plugs faded when I found out that a third of the recommended NGK auto plugs are counterfeit. I’m just confident the self power part isn’t a concern.
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Toobuilder
Well Known Member
Not sure if you are in the minority or not, but its clear there's a good number of pilots who don't. But as a method of fault detection its a pretty course screen. There can be no expectation that the internal generator will continue to work until the next test event. Probably will, but without ongoing fault detection, who knows. It's exactly why we have the "idiot light" for the alternator.
Same here - I have never done a runup without checking the internal alternators . At annual I also check the rpm that they start to drop out.
Toobuilder
Well Known Member
At the system level (engine runs until landing), I agree. NBD. Same with most other EIs. The engine will run, with reasonable backup schemes in place. At the same time, the "self powered" attribute loses much of its shine due to the less than stellar reliability at the component level. Like most things in aviation its a trade, its a compromise.
The data stream provided by the EMAG does include voltage. The raw value doesn't match ship's power so I'd assume this is the voltage that the EMAG is running off of (ship or internal power). The issue I would have creating a warning light is that we have no details on what the range of voltages means. Something like < 10 running on ship >= 10 running internal power for example. Then it would be easy to add in a warning light but without it would just be guessing.
Toobuilder
Well Known Member
I think the indication that the ignition did a mode shift as a discrete event is the data the typical pilot needs.
Failed/not failed... no fuzz on that peach
Edit. Pulling on that thread a little more, it seems a "mode shift" indicator would be great for run up too. Pre engine start the light is on; once stable at idle the light should be out. If not, you don't even have to wait to do your "test" at the end of runway. Further, one could pull the idle way back and see the light come back on when it shifts to external power.
Seems like this light could eliminate a bunch of switch throwing and pre takeoff process. When one of you EE types build this thing please send me the royalties!
Failed/not failed... no fuzz on that peach
Edit. Pulling on that thread a little more, it seems a "mode shift" indicator would be great for run up too. Pre engine start the light is on; once stable at idle the light should be out. If not, you don't even have to wait to do your "test" at the end of runway. Further, one could pull the idle way back and see the light come back on when it shifts to external power.
Seems like this light could eliminate a bunch of switch throwing and pre takeoff process. When one of you EE types build this thing please send me the royalties!
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The current firmware and data stream provides a mode. But that mode is just 0 for startup mode and 1 for normal operation. To back into the internal alternator working you would have to know what voltage ranges provided in the stream corresponded to ship power vs internal power or if that was even feasible to use as a logic test. Takes less than 10 seconds to a check during runup but it would be nice to have an indicator during flight if the internal failed. If I ever get some time I'll add the voltage to to my screen and see if I can't figure out a correlation.
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akschu
Well Known Member
I'm with Dan on this one, it screams diode or'd instead of some kind of power controller which would report some sort of status to the microcontroller. I suspect it doesn't have a way to know what's up internally.
Toobuilder
Well Known Member
Well, there goes my million dollar idea!
