My P-Mag Failure

[Brantel]

CATpart,

Once a Pmag is running and the RPM is >~ 800rpm, you can't shut it down to the point where this lockout can happen. Just grounding the P lead won't do it. The Pmag is self powered after the RPM comes up....

[CATPart]

Thanks brantel, I thought that was the case, but this means the prop must be windmilling right? I have never flown in an engine out situation, but this rv4 power off landing video does not assure me that the prop will be spinning should you lose power. Would the guy in this video have been able to restart his engine with that error code?
http://www.youtube.com/watch?v=G73oTrVVdKc

edit...I just reread the first post wondering why one bad mag kept the plane from starting....well obviously he said he started and restarted, so it was the rpm indication that kept him from flying. I get it now

[Brantel]

Per Emagair, this lockout condition won't happen in flight (with a turning prop) so it won't be responsible for an engine failure. If the Pmag fails hard enough to cause an engine failure, this lockout will be the least of your worries.

That's also one of the reasons why we run dual ignitions.

That guy's airspeed was low when he shut that engine down.

[N184DA]

I have dual P-Mags, circa 2013, (#114's) on my RV4, and i had the exact same issue yesterday, at a fuel stop two hours from home, and two hours from my final destination.

I won't repeat the details of the original post, sans to say, that except for a name change, details are identical.

Fortunately, the FBO (Western) at KRBG was staffed on a 100 degree Saturday, and I was able to move my 4 inside the hangar, out of the heat to work on.

Although my Pmags are several years old, I doubt they have 100 hours on them (Yeah, that's another story,,)

A call to Brad's emergency contact line was successful, and he managed to talk me and the mechanic through a process where we "tricked" the mag and cleared the fault, which allowed me to get home. This involved removing the P-mag, checking for excessive shaft wear (we could not detect any out-of-bounds play), reconnecting the p-mag,with power prior to installation, manually setting the gear position, and reinstalling,, all the while without interrupting ship power. Very similar to the old-fashioned method of setting a mechanical mag.

Anyway, it worked,, two hours delayed, and I was able to get the 4 to it's destination. Now, I will have to remove BOTH P-Mags, and send them in for a factory check, and while I am at it, a firmware upgrade.

First of all, I can't say enough about Brad's customer service, assistance, and availability. I must have called him at least 17 times yesterday, as we were working through the process.

Having said that,, as happy as I am with Brad, and the P-Mags,, when they work,, I fear this experience will leave me feeling a tad uneasy with future flights away from home. Sure, there are any number of things that can break on our airplanes, leaving us stranded,, but the recent history and uncertainty of THIS particular problem, will leave me second-guessing any flight, away from home base. At least for awhile.

No, I am not considering going back to slicks,,
The overall advantages far outweigh the temporary, uneasiness,,
Hopefully, when I receive the re-conditioned mags, this problem will be history.

I am with the other commentators in this thread,,
Would be nice to have a panel mounted LED indication. I can see the right mag, okay, from the oil-door (still requires a mirror to see the LED). The left, (which of course is the one that failed!), requires some very tricky maneuvering with a mirror and flashlight. So checking the LEDs BEFORE powering off the electrical system is simply not practical.

And really, after thinking about it,,
What would I do if I DID notice the yellow LED prior to shutdown, away from home,,? This could open the door to all kinds of interesting discussion,,
Do I "ignore" the fault, and assume the shaft is still okay enough to attempt another flight,, or would I take steps and attempt to remove the mag, wherever I am before the next flight,,
Lot's to consider,,
Risk to just myself, a passenger,,?
remoteness of the field,? Day/night, weather,,
Holy cow, I don't want to go there!

BTW

Another well deserved shout-out to JD at Western (KRBG),, without his assistance, and willingness to allow me to work in the shade, this "experience" would have resulted in a logistical and costly nightmare!!

[N941WR]

Emag came out with the Version 40 firmware upgrade three years ago that fixes a number of issues with the P-mags.

Anyone who has not had that upgrade done will have issues eventually.

When doing your condition inspection, please check all your vendors for service bullitens.

[N184DA]

Originally Posted by N941WR

Emag came out with the Version 40 firmware upgrade three years ago that fixes a number of issues with the P-mags.

Anyone who has not had that upgrade done will have issues eventually.

When doing your condition inspection, please check all your vendors for service bullitens.

I could be wrong but the firmware upgrade, alone, would not have prevented this particular failure. From my understanding, it has more to do with the placement of the sensor during assembly.

[Bevan]

One could route a fibre optic line from the LED on each Pmag to the cockpit where The LED could be viewed" from the cockpit.

[N941WR]

Originally Posted by N184DA

I could be wrong but the firmware upgrade, alone, would not have prevented this particular failure. From my understanding, it has more to do with the placement of the sensor during assembly.

You are correct. The Version 40 upgrade would not have helped.

[johnbright]

FYI loose alternator wire untimes pmag if you don't have version 40 firmware.

Crital flight issue.

Ref http://www.vansairforce.com/communit...d.php?t=144336

[Noah]

Originally Posted by Bevan

One could route a fibre optic line from the LED on each Pmag to the cockpit where The LED could be viewed" from the cockpit.

I have done this. It's a little faint but works.