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ANOTHER P-Mag failure!

tkatc

tkatc

Well Known Member
Flying the other day I was leaning out the mixture and noticed exceptionally high EGTs. So I fed in more gas and she cooled down into the green. Leaned again and again, high EGTs. Tried it a 3rd time and it was normal. This puzzled me. I also felt a surge of power once while taking off. Wasn't real sure about that either. I landed and before departing did a routine mag check. The engine died on the left mag.

Uncowled and looked for obvious problems. None found. Started it up the next day to troubleshoot. This time the routine mag check worked fine but the engine died while checking the left p-mag's "internal" power. I removed the left P-mag and discovered the drive gear was "crunchy" when rotated. I just went through this with the right p-mag about 20 hours ago so I am sure the magnet has once again dislodged and partially disintegrated. We'll see if I have to pay for new circuit boards again! The P-mag is on its way to EMAGair....
 
They are 113s. Approx 360 hours. First went into service in 2006. They DID have the SB done regarding the magnet attachment.
 
Thanks Tk for the update.

Mine are P114L's. As you know, they only have about 135 hours on them and until I get to the "Vlad" level ;) I can't comment on how reliable they are.

Knock on Wood, Metal and Composite propellers.....mine have been running well.

Good luck,
 
tkatc said:
They are 113s. Approx 360 hours. First went into service in 2006. They DID have the SB done regarding the magnet attachment.
Click to expand...

Lots of changes since 2006 if I recall following the development here through the years. I suspect that you will find that with identical vintage equipment, you will have had a very similar failure - engineering works that way.

I have watched the development of most of the EI systems out there, and have hepled rescue friends by flying parts and mags to those with pretty much every system out there - inlcuding Slick mags (and Bendix mags).

I stayed away from the development years of P-Mags myself, but there are now lots and lots of folks flying without failures (with th late-model units).

Paul
 
tobinbasford said:
TK,

My sincere recommendation is to go with Light Speed. With no moving parts, malfunctions are very, very rare. LSE has a long history having been around since the 80s and is very proven. Here is there website: http://www.lightspeedengineering.com/. There are thousands of airplanes flying with LSE. I'm not bashing Emag/PMAG because I've never flown with them, but I can't count how many times I've read about their failures on this forum over the years. Just my .02. I know some folks swear by Emag/PMAG.
Click to expand...

different perspective:
Light Speed Plasma III complete failure on take-off in my BD-4... Klaus was a complete "something I'm not allowed to say here" and blamed my installation - even though it worked the two previous hours. Turned out to be a failed mother board. Klaus then explained the significance of infant mortality and acceptable probabilities of electronic components and that failures should be expected...thats great for a 21st century toaster but not ok for an aircraft ignition 2hrs old! Eventually received a total refund but not without a struggle. This was 2006/7
 
Ironflight said:
I have watched the development of most of the EI systems out there, and have hepled rescue friends by flying parts and mags to those with pretty much every system out there - inlcuding Slick mags (and Bendix mags).
Click to expand...

I think this is a key point. I've seen EI and mag failures over the years, both first and second hand, and have read about plenty of failures in these forums and on the Matronics board. EI failures are often more frustrating than mag failures because their complexity makes them harder to troubleshoot. Also, EI's tend to cost 2x what magnetos do, and people expect equivalent or better reliability for 2x the price.

That said, I suspect a pair of Slicks (or Bendixes) would be more reliable than a system with one or more EI's. Aircraft mag's have been refined for 100+ years. EI's for a fraction of that.
 
Ironflight said:
Lots of changes since 2006 if I recall following the development here through the years. I suspect that you will find that with identical vintage equipment, you will have had a very similar failure - engineering works that way.

I stayed away from the development years of P-Mags myself, but there are now lots and lots of folks flying without failures (with th late-model units).

Paul
Click to expand...

What is considered "late models"? And if these "early models" are so failure prone, why have these 2 p-mags been repaired twice at the factory and sent back into service?
 
Kyle Boatright said:
That said, I suspect a pair of Slicks (or Bendixes) would be more reliable than a system with one or more EI's. Aircraft mag's have been refined for 100+ years. EI's for a fraction of that.
Click to expand...

That is probably true. But, like everything, unless your ONLY goal is reliability, you have to make trades. EI's have some significant performance advantages over Mags. The question is not if the EI (or mag) of your choice is the MOST reliable ignition available, it is rather if it has reached a sufficient level of reliability to be considered for use.

Paul
 
Good experience

Just one data point but have beer running 114s for two years with 125 hours and no problems! Excellent first blade starting and zero plug fouling! I'm a happy camper :)

Bill s
7a
 
Ironflight said:
Lots of changes since 2006 if I recall following the development here through the years. I suspect that you will find that with identical vintage equipment, you will have had a very similar failure - engineering works that way.
Click to expand...

There hasn't been any change in the magnets used or the way they are attached since the service bulletin some years back. This same problem happened to me recently and based on Brad's description, the repair doesn't involve anything new. They just replace the magnet with a new one using the same attachment method. I suspect heat and vibration are the root cause. Don't anyone for an instant think that because you have the 114s that you are immune to this. There is no real cure to be had at emagair, just repair. Be sure to do your runup tests, and watch for elevated EGTs and loss of rpm reading during flight as clues that you have lost a mag. And be sure to report back here regarding new failures.

Erich
 
While at Osh I spent some time talking with Brad about this exact failure mode. He had a unit there taken apart and showed me how it all works and what failed on these two and now three units.

Due to the small clearances involved, it seems that the Pmag could be damaged by impact to the shaft, radial or axial pre-load on the shaft, sudden stoppage, dirt and grime, etc. Many things could initiate this failure.

It looked to me like that if the magnet ever got even slightly damaged, it was almost guaranteed to start a cascade failure to destruction due to the tight clearances involved.

Not sure what to make of the data at this point since we have reports of units going many more hours with no issues. Two of the three failures reported are from the same airplane and happened within 20hrs of each other. Then we have a third isolated report.

Mine might fail on the next flight but so far it has given me ~140 hrs of flawless performance.
 
So the excellent and prompt service continues. My P-Mag is on its way back to me, repaired free of charge.

Apparently, there are 2 magnet areas inside the P-Mag. One handles the timing sensor, and the other handles power production as they rotate inside a static stator.

My first failure was the timing magnet, the one that is addressed in the SB. The magnet disintigrated so badly it coated the board and could not be cleaned. Thus, I needed a new board and was charged for that board but not labor.

The second failure was the stator related magnets, or so it is deemed by Emag because it gets messy in there and that is the most likely culprit given what they found inside. They repaired this failure completely free of charge as no new board was needed.

I have not had any ELECTRONIC issues with P-mags so I remain confident with that portion of the product. I do question the magnets and/or the adhesion techniques used in production.

One last tid-bit, I had a lengthy conversation with Brad about possible scenarios and preventive actions that could be incorporated. He explained that on this latest failure, in theory, it was possible that the shaft developed some play and that play allowed the magnets to rub something causing the failure. He suggested that at annual, I remove the ignitions and check for such play. Seems reasonable but that certainly is not a cure.

I do not know what direction I will choose when I approach the ignition decision on my current -8 build. I guess that will greatly depend on how much trouble, if any, I experience with my current (and flying) P-mags. I will say that service IS second to none. They DO try very hard to take care of you when issues surface.
 
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