PMag Problem 114 model

[Veetail88]

I experienced a problem with one of my P-Mags yesterday.

Having flown for only about 20 minutes, I landed for fuel. With fueling, chatting and screwing around a bit, I jumped in to head out. Start-up went fine, but the motor seemed to be a bit odd with little misses here and there.

When I ran my ground mag check (which I almost skipped as I'd been flying just 30 minutes before and will never think about skipping again) I had no rpm drop when I grounded the left P-lead. Checking the other P-Mag, the engine lost ignition completely. Left P-Mag, dead.

Knowing that if the problem were ship's power the P-Mag would keep going I figured either the P-lead connection was bad or the P-Mag itself had gone tip up.

Taxied over to a hanger where I had a friend, I pulled the cowl off to check things out. With the motor to warm to really work on, I accepted a ride back to my hanger for tools and wiring schematic and such.

I pulled the connector and tested. P-lead, ground and ship's power were intact, so I plugged it back together fired up the motor to check it out. Everything was fine. Cowled it back up, fired it back up and everything was fine so I launched for the home turf. All systems go, no sign of any problem.

I have no clue as to the problem and have not been able to find exactly this problem anywhere in the archives here. The connector was secure and everything in good condition so I don't believe that was the problem. I didn't think to try to power everything down and restart when the condition first showed up.

Having read posts about heat problems here, I suspect that was the problem but that's based on nothing concrete. The day was I think around 76 degrees F and I don't have any overheating tendencies. Seems the heat soak might have been the problem as it was a good hour with the canopy off between the event and the restart, and things were substantially cooler.

I do have blast tubes installed by the way. I purchased the units 5 years ago but only started flying them last August. Pretty sure they were built after the teething problems were worked out. They have 55 hours on em.

I have not had a chance to try to recreate the event yet, but if things clear up today I'll try to get a flight in.

Anyone seen this issue? Any clue?

Thanks.

[Chkaharyer99]

Sorry to hear of your problem. Yesterday I was looking at the archives for "P-Mags" as I'm and considering changing over from Slicks.

I do recall reading about someone who had a similar problem. I don't remember the specific thread or post.

[Chkaharyer99]

I'm pretty sure it was in this thread but don't have time to look:

"PMag Issue" Google search "VAF PMag Issue"


http://www.vansairforce.com/communit...d.php?p=930093

Best,

[lr172]

I have no experience with Pmags, but some with electronics. My experience is that devices with logic processing chips can encounter numerous anomalies that are solved by resetting (power down). I would hope that something like a Pmag would build in solid error handing and resistance to these anomalies. I would call the Mfg to see how often these types of situations occur (i.e. no operation solved by reset). If it is known to happen occasionally, I probably wouldn't worry too much. I am sure they will offer guidance.

I will also say that heat is not a friend to electronics and most aren't built for the 200* temps you can see under the cowl shortly after shut down. However, it is possible to design for well over 100C with the right components and manufacturing techniques. I would assume that the Mfg accounted for this and designed and tested accordingly. Again, I would ask how often or if they see heat problems.

Good luck,

Larry

[DaleB]

Also not a mag expert, but I have spent more than couple of years maintaining and repairing electronic equipment in various environments. I do plan to use PMags, and one of my annual condition inspection items will be to remove and re-seat both connectors on both mags. Any sort of pluggable connector can, and in my experience probably will at some time during its life, develop some oxidization or contamination that will cause intermittent problems and require its re-seating. The contact wiping action is usually enough to "fix" whatever problem you've encountered, just by removing and re-plugging the connector.

On card edge connectors and accessible pins I normally use a pink pencil eraser (very mildly abrasive). Any repair guy who has been around a while can tell you why he has a Pink Pearl in his tool kit.

[Veetail88]

Just repeated the scenario from yesterday with the same result. :-(

Guess I'll pull the offender now and call the mfgr in the morning.


UPDATE:

Pulled the cowl and powered up the P-Mags. The offender has a blinking yellow LED.

From their website

1. Sensor Magnet Range Check - Every time the ignition powers up, the ignition first performs a
self-test to verify the sensor magnet is within an acceptable range. If the Range Check
passes, the ignition proceeds with initialization (no LED signal). If the Range Check fails, it will
proceed no further and will signal an alert with a pulsing (approx 1 every quarter sec) YELLOW
LED. From the operators perspective it will appear as a non-operative ignition. The flashing
YELLOW will continue until the infraction clears or the unit is powered OFF. No record of the
alert remains after power OFF.

I'll call them in the morning and get it in for repairs.

[RFazio]

I've got a new set of pmags in my RV6. I've got maybe 10 hours on them. It's been running really good. Yesterday I was giving young Eagles rides for about three hours. We finished all the rides and I was on the way to my home airport, about a 10 minute ride. I noticed a slight miss. Almost like I was too lean. Played with the mixture, I was full rich, no change. Then I switched the mags to left and right. The right mag was missing real bad. The engine was running but very rough. I switch it on and off a few times and the problem went away. Fine the rest of the way home. By on and off I mean grounding the p lead only. Once home the problem was gone.

[N941WR]

Jesse,

Yes contact Emag, they will take good care of you.

Originally Posted by RFazio

I've got a new set of pmags in my RV6. I've got maybe 10 hours on them. It's been running really good. Yesterday I was giving young Eagles rides for about three hours. We finished all the rides and I was on the way to my home airport, about a 10 minute ride. I noticed a slight miss. Almost like I was too lean. Played with the mixture, I was full rich, no change. Then I switched the mags to left and right. The right mag was missing real bad. The engine was running but very rough. I switch it on and off a few times and the problem went away. Fine the rest of the way home. By on and off I mean grounding the p lead only. Once home the problem was gone.

Richard, this sounds like it could be a different problem. Did you buy your P-mags new or used. Either way, do you know what firmware version you have on both P-mags? Do you have a key switch or toggle switches for both? Also, how did you wire yours up, two pullable breakers and grounded to the engine case?

I ask because yesterday I helped a guy with his and they were wired so odd we couldn't even set TDC. He is going to have to rewire his plane before he can start his engine.

[mattsmith]

Jesse, I had the same exact thing hapen with about 10 hours, except when I contacted E-mags I could not get the left mag to malfunction to see if I had the yellow LED.
The problem has not reappeared but I have only been flying since October and now have 50 hour's. Please let us know what you find. Spellin

[N184DA]

FYI:

Benn running dual P-Mags in my RV4 for about a year, with no issues,, except:
Within five or so hours of initial install, I had a similar issue,, intermittent misfire.
Would come & go, but at one point, got so bad, I had to cancel a flight after the run-up.

My problem were the factory installed connectors, most of the individual terminal screws were loose.
Granted, I should have caught that during the install,,, but, I didn't :/

Ever since, trouble free,, I love them!