P-Mag Operating Temperatures
 

P-mags contain an internal temperature sensor. Temperature output is available via laptop or EI Commander. Has anyone actually measured the internal temperature of their P-mags with and without blast tubes?

You know that Bill Repucci is the best guy to answer this...or anyone that uses his EI Commander. I'll be interested to see what the responses will be.

BTW, Dan, the whole reason I started that thread about measuring cowl pressure differential was because of a conversation that I had with Brad at eMag. I was perfectly content with my "slightly high" temps until he told me that I could experience thermal shutdown if they get much above 210 (F).

This conversation took place because I sent my Pmag in for repair and he said that the thermal sticker on the outside was tripped. I want to say that it was a 200 degree sticker, but maybe it was only 190.

Sonny - good info and thanks. I have one P-mag and one slick. I'd be willing to block off the blast-tube to the slick, never had one in other planes I've owned, but probably leave the P-mag alone.

Maybe a stupid question...but
 

wouldn't the temp rise above 200 upon shutdown if you are operating in a high OAT enviroment? I think I've had a conversation with Bill about this...as the EIC only records the max temp...not the current operating temp? Am I missing something?

v/r
John

Brad was fairly vague about the "thermal shutdown" of a Pmag, but he did say it's a risk. I said it was over 210, but I think Brad actually said "around 220" is when the risk becomes real. Either way, my impression is that he is being very conservative and for good reason.

I really don't know when or if a Pmag would shutdown from getting too hot. I would hope one never does, but I wouldn't pin my life on it. He said to put blast tubes on it, and my guess is that they don't want to see them get much over 200...so that's what I'm doing.

Dan and I spoke earlier in the week but I didn't have an answer for him. I hope to get out this weekend and block one of the blast tubes and watch what happens. (If the temp goes too high, I can shut off the one ignition and get home on one P-mag.)

The P-mag records the max temp, not the EICommander. However, the EICommander will display the current temp.

You are correct, on a hot day, if you land, shut down and do a quick turn, the P-mag will be heat soaked and will record the high temp it sees when you power them back up. Unfortunately, there is no way for the EICommander to clear the high temp recorded in the P-mag, that has to be done at the factory.

(We have asked for the ability to clear this temp and have been turned down. We did talk about recording the max temp in the EICommander but discounted it because it would only record the max temp on a hot / quick turn, same as the P-mag.)

Perhaps a Latent Problem Remains
 

Given there are now many more fleet hours on P-mags than when the SB3 was released (three years ago), problems just don't seem to be going away, though VAF has been fairly quiet.

I have personal knowledge of two other ships that this week had their ignitions back to E-mag for failure issues, and both had SB3 incorporated.

One requires some adjustment to shaft end play (a point mentioned in SB2). So why is this now apparent and wasn't back at zero time?

The second failed in the classic lost timing mode wherein all h*ll breaks lose on power up for take off. (I've been experienced this twice myself.) Here's the owner's report to me. "Brad initially denied that there was a problem with Pmag but today he told me he had an ?anomaly? when he first checked it but couldn?t replicate. He replaced the main circuit board (said it had discoloration from heat in one spot) and replaced the coil. $450 later it is being shipped back today."

I know another local pilot who crash a few seconds after take-off. Supposedly the cause was fuel starvation, but another pilot familiar with the sound of ignition failure is convinced a failed ignition is the culprit. This remains conjecture since the owner has yet to have E-mag check his ignitions. I remain highly suspicious.

My concern is that P-mag electronics are proving razor-thin close to getting cooked in their natural, normal operating environment. Brad once told me they conform to the same temperature spec as magnetos, but the only thing electronic on a mag is the capacitor, and it's loss only hastens point erosion, not instant failure.

So let's have a show of hands: who has had, or has first-hand knowledge of, P-mag problems in the last three years? Electrical or mechanical difficulties? Was SB3 incorporated? Blast tube or no?

I'm real interested in Bill R's report.

I know P-mags have shut down protocols if something's out of whack at start-up. But to shut down an operating ignition to save itself seems as looney as sawing off the limb between you and the trunk. And if it shuts down because it can't hack it's natural environment, that's a design problem.

John Siebold

Keep on mind that the guys from Emag have stated that the internal temp sensor is not calibrated and may not be accurate.

This Just In...
 

One of the pilots in my above post has a further tidbit from Brad.

The on-board temperature recorder is unreliable. There's enough RF about to sometimes set it off, recording an impossibly high number. E-mag therefore is not relying on it as gospel.

Of course, the external dot only monitors its immediate locale, a poor indicator of what's happened internally.

John Siebold

Discrete component temperature range
 

The type of capacitors that you find in most magnetos have a maximum operating range of 85 or 105?C (185 or 221?F), depending on the manufacturer. I hope that they use the ones with the higher rating but don't know for certain. Regular industrial grade silicon based, PN-junction components (transistors, ICs, etc) normally have a maximum operating temperature of 85?C while mil spec versions of the same components have a max operating temperature of 125?C (257?F). Again, I hope E-mag uses the better versions in their products but don't know that to be fact. Heat is the enemy of any electrical circuit. Magneto manufacturers recommend blast tubes for the same reason that E-Mag does. Cooler operation is better for the life of magnetos, E-Mag products, or any other electrical/electronic device.

My friend had chronic CHT and oil temp issues in an RV4 (severe cam problem related to poor machine work for fancy new camshaft) and never had any noticeable heat soaking problems with his P-Mags in Gulf Coast summer heat. He did have blast tubes and they were the 113 versions, before the extra cooling fins machined into the case. He's a member on here so I welcome him to chime in with his first hand experience.

I personally cannot speak to operation in high ambient temperatures because the Alaska climate is well suited for operation of such accessories. My maximum temperature is recorded as 184?F and that was probably recorded during the first couple of flights before the blast tube was installed.

However, my P-Mag did have a mechanical failure at about the 220 hour mark due to the failure of a small component (finger spring washer IIRC) on the shaft causing misalignment of the shaft position sensor. The washer most likely failed in flight but the ignition kept on ticking until I tried a restart after refueling. During initial troubleshooting I discovered a blinking amber LED on the P-Mag indicating shaft misalignment. Rotating the prop and recycling the power (tried this sequence about 5 times before it was successful) allowed me to restart the engine. Doing this outside at an OAT of -10 sucked though. It was well beyond the warranty period but Brad at EMag fixed it for the cost of shipping, $15. If I got that kind of service when my Slick magneto experienced a problem at less than 100 hours (albeit 4 years after initial purchase) I may still be using it. That's when I decided to upgrade to the P-Mag EI as a replacement in the first place, and I'm still happy I did.

Temperature control
 

As one of the two recent failures referenced by John above, I am convinced that my failure last week was temperature related. I had just dropped off a passenger with a short shutdown followed by a hot start and taxi for takeoff. Failure (apparent loss of timing) occurred at start of takeoff role.
So, after replacement of "temperature dicolored circuit board", is there a science to pointing the blast tube at the right spot on the Pmag? Thanks for the help.

Bruce McGowan

I have 1 P-mag and a slick. I can't even begin to count the number of hot-turn-arounds I've done in the last 200 hours without any ignition issues at all (knock on wood) most of those during 95 OAT days in Southern Florida. I do have 3/4" blast tubes. FWIW

Bruce, please contact me off list regarding your failure.

Thanks!
bill (at) repucci.com

Dan,

Family issues came up this weekend and I didn?t even make it to the airport. Rain is expected for most of this week, so we may have to wait until next weekend for a temperature test.

Bill

Absolutely no problems with mine. I love it! Latest design and firmware.

Installed per the directions with a blast tube blasting on the fins of the Pmag.

My taddle tale sticker has never tripped and I see 400F on most climb outs.

E-Mag Blast Tubes
 

I have just installed 2 E-Mags on my RV6 with O-320 and I am looking for the best blast tubes to use and a way to install them. Any pics and suggestions. Once I get these on I can fly. :D
Tony

I have two P-Mags in my RV7, 114 series, purchased second hand on this site, blast tubes are installed, latest software timing upgrade not done.

Over Christmas we did a series of joy flights for our staff, 1.5 hours of start stop activity in 37 deg C (98F) heat and had no issues at all, I know we are crazy but our staff loved it, bumps and all.

Cheers

One more data point. I've got a sensor glued to the outside top of my left PMAG.

In flight at cruise altitudes it's always pretty cool around 120-140F.

On shutdown the temperatures rise quickly.

Here's the hottest flight I can remember since installing the PMAG. It also involved a quick turnaround. OAT on ground around 40C.
On startup the Temp was around 200F. Didn't really drop below 175F until TOC.


Standard blast tube install.

FYI - The internal temperature probes on the P-mags are not calibrated, thus any temperature displayed by the EICommander or using the EICAD program should be taken with a block of salt.

I hope you have P-mags and not E-mags installed. Emag is the company and they used to sell E-mags which where the same as the P-mag, less the internal generator.

Please get them in for the version 40 upgrade. It is critical, if you have toggle switches as it is a sure bet you will start the engine with one grounded and one ungrounded, which will reset the grounded mag.

(This upgrade will also help with starting as it sets the timing to 4 degrees after TDC when below 200 RPM. Above 200 RPM and the timing goes to 19.6* BTC at low RPM settings.)

I have the ACS key switch with the jumper removed, so both Mags become live at the same time

I have for the last year had the PMags timed to fire at approximately 4 degrees after TDC to ensure no kick back etc.

I initially ran the PMags with the timing at TDC but did experience the occasional kick back, since the timing change I have had no more kick backs and cannot notice any difference in performance, although I am seeing cooler CHTs as would be expected.

I am also running with the PMag jumper installed.

I would love to get the upgrade, but being in Sydney Australia there would be quite a substantial lag involved in shipping and them getting the units returned.

When I bought the two units, I contacted Brad and sent him the serial number information, he stated that they should be fine the way they are currently wired.

If only there was a way for end users to do their own software updates ???

Cheers

P mag blast tube improvement
 

An idea I had when installing my 2 Pmags was to make an enclosure around the finned area of the Pmag to help make the air blast more effective. It seems like a poor application of cooling blast air to simply blow the air at one location. An enclosure that would route the cooling blast around the Pmag finned are and then out the bottom would seem to be more effective. Something like the shroud I have that surrounds the mechanical fuel pump. Maybe as simple as a rolled piece of aluminum formed to a radius that would allow it to be sprung open to put it on but still clamp itself in place, with a flange in place for connecting the blast tube, pretty simple really, but I did not do it.

Seems it would be fairly easy to make one but I went with the recommendation and just use safety wire to hold a 3/4" blast tube in position.

Has anyone tried making a cooling air shroud for their Pmag?

My temp stickers have not tripped and I have one summer of Arizona hot temperature operation with no problems, happy customer.

Randall in Sedona

You should be fine. Since you have a key switch which ungrounds both P-mags before engaging the starter, you should not have an issue.

We have spoken to Emag about letting customers do their own software updates and our feeling is they don't want users messing with them at that level, for whatever reason.

The good news is, we (Us at EICommander) haven't heard of a single lost timing issue with installations using a key switch or after the V40 update.

These are the blast tubes for the 2 pmags I have.
I also monitor and record the temps on both pmags and the rear cowl section. My MGL allows me to add many temp probes. During flight the pmag temps run ~ 150's to 170's depending on the flight conditions. The cowl temp runs ~ 130's to 140's.




I find the pmags to be far more unreliable than most people know.

FasGlass: What temps do you see shortly after refueling on a hot day?

Hi Bill,

That is good to know, I have nearly two years on my second hand PMags and have to admit I am a very happy customer.

Cheers

FasGlas what issues with pmags?
 

G'day FasGlas,

I only have 100 hours on mine and so far no problems but I am interested in the issues you have experienced which prompted your statement in the quote above.

I have a little cooling duct to each as recommended in the install manual and the max temp they have reached so far is 190F (based on a temp tape on each of the bodies), which coincides with my maximum engine oil temp.

Regards
Nigel

The fact is if you don't have your pmags connected to an EI Commander or a laptop with EICad you have no idea what the pmags are doing.
After running two pmags for two years (with an EI Commander) and having nothing but problem after problem with both of them, and after getting PM's from other pilots with problems, and pilots in my group with pmags that have had problems, I can say without a doubt that pmags are unreliable and inconsistent. I have lots of data to back this up.

Please share
 

Randy,
Please share your data and info. I'm sure many would be interested in your findings.

This may take a little work to compile and post pics and data. The forum only allows a few pics to be linked to a post. I have many pics of my EI Commander showing all the anomalies of my pmags.

Or you roll your own monitoring solution.

5 years of great service from my P-Mag. It may die tomorrow but so far it has performed as advertised.

Do those anomolies correspond with engine performance problems? In other words, if you did not have the EI Commander, would you notice any problems? Is this simply a matter of having "too much" information to study, similar to the fantastic amount of data supplied by current engine monitors - and the recent focus on exact EGT, CHT, and related perameters that in past decades we would blissfully ignore?

As one more data point, I have several summers worth of desert flying (including a take off on a 121 degree day) with no issues on my 113 series Pmags. Just a simple 5/8 inch blast tube aimed at the neck of the alternator.

FWIW I have 180hrs, and counting, on dual P-mags with no problems whatsoever. I also have a simple 5/8" blast tube aimed at the P-mag necks.

:cool:

I'll answer this for Randy.

For the most part you are correct; however, Randy purchased a used set of 114 P-mags which were never "right" from the factory.

He recently replaced the board on one P-mag board and that solved most of his issues.

One thing the EICommander can do is tell you if the ignitions are firing at the same time. When we designed the EIC, we ran into issues when the RPM dropped below 500 RPM, so thinking no one would run below ~650 RPM +/- the Timing alarms are somewhat unpredictable down below 500 and because of the airplane he is flying, he has his RPM set in the high 300 RPM range. (I had no idea a Lycoming could turn that slow.) This low RPM, coupled with the averaging routine in the EIC makes it look like he has a timing issue; however, when he powers up for flight, the ECI report correctly and his timing divergence alarms go away.


The following are some general comments regarding P-mag operations and configuration, not necessarily related to Randy's issue(s):
The EICommander is a very sensitive instrument and we have done our best to eliminate false alarms, thus there is a pretty sophisticated averaging routine in our code and it will not alarm until we know there is an issue.

Here is a short list of things we have found that can impact the P-mags but you would never know, unless you have an EIC:
1. Setting the timing in one P-mag and then the other. (Solution: blow in the tube and set both TDC marks with the same breath. Don't ask me why, but it has been an issue.)
2. Ground the P-mags to the engine case bolt, not the forest of tabs and run a second wire from the P-mag directly to the EIC, not a forest of tabs. The EIC can pick up odd signals from other electronics on the ground bus.
3. Run the tach wires from the P-mag to the EIC and a second set of wires from the P-mags to your EFIS. Although they connect at the P-mag, separate wires seem to be important.
4. Install a good pressure stabilizer in the MAP line.
5. Make sure you have good quality mag gears installed on the P-mags. (Emag used to sell gears that were not properly case hardened and have been know to wear prematurely.)

The list goes on but most things are fairly simple to do and are good building practices.

Even with #5, the only way the pilot knew there was an issue was because of the ECI's Timing Divergence Alarm function. The coil pack data display has found a number of bad plugs, bad wires, coil packs, fouled plugs, etc.

While you do not need an EIC to fly with the P-mags, we appreciate Randy's confidence in our instrument. A number of our clients now insist that they will not fly without P-mags and the EIC. Think of it this way, most will not fly without a full EMS to display the health of their engine. The EIC is an EMS for your ignition.

If any of you have questions about your set up, feel free to contact me.

As far as known issues:
I have worked with a number of people with P-mags (with and without the EICommander) and apparently have found far fewer problems than Randy has eluded to. Granted, the early 113's had problems with trigger magnets falling off (since fixed) and software issues (since fixed). And there is the occasional hardware failure issues (Heck, we have even seen that with the EICommander and strive to improve our product and resolve customer issues quickly.), but for the most part, I believe they are proving themselves more reliable than standard magnetos.

For those of you who have not followed the issues, this thread should give you a pretty good idea of best practices with P-mags.

What exactly is this?

"4. Install a good pressure stabilizer in the MAP line".

I suspect most folks just tap into the MP line.

Please understand that I was asking a question, not making an assertion.

Anyway, The question was rooted in determining if the anomalies were "caused" by information overload, or if there was a legitimate issue with his particular configuration. I'll take anyone at their word that they have experienced problems - there were a few in the early days that could not make Pmags work despite heroic efforts by Brad and company - but when those people make a blanket statement that Pmags in general (i.e. as a product line) are "unreliable", then we need to dig deeper. Maybe it is the individual installation that is the cause? Particularly when many of us have had stellar service from our Pmags. And I do have a good friend who is one of the very early adopters of the Pmag AND EI Commander and has no issue flying his Glassair in "hard" IMC. He has not seen these issues either. The only issues I've had were self induced when I used non-resistor plugs.

So it still is a question whether these issues are a result of TMI (over analysis), highly isolated/self induced, or as posted in #23 and #27 - widespread.

That can be good and bad. Some modern EFIS's "smooth" the MAP indicators, even though the actual pressure is bouncing all around.

It really takes a restrictor, up stream of the P-mag MAP line, to give good, consistent readings for the P-mags.

OK!! HOLD THE PHONE HERE!!!

I have never bought a set of 113 pmags. I bought a pair of 114 ver 36 pmags and an EI Commander from a guy that bought this all, installed them, the pmags didn't work, they were sent back to emag, returned and still didn't work. They were removed and I started to work with them. This i where I came into this story.

I installed them with the EIC. I took them out flying and the first thing I noticed was the extremely hot CHT's. I ran the timing back and got the CHT's down to a tolerable level. Next the timing on the pmags started jumping all over the place. I sent them back to emag where they sat for 5 weeks, then returned to me in the exact same shape. I was supplied with an old used replacement board (guess I'm supposed to fix them myself). I replaced the board on the left pmag and the left timing stopped jumping. Now on to the right pmag. I took it apart and cleaned out the body and sprayed down the board and connectors, reinstalled it and retimed them, at this point they both seemed to hold the timing. I put some hours on them and learned to live with the best they could do, high CHT's and not much added power.

Next I fly from SoCal to OSH. On the way there and back (18.2 hours total) the EIC would display as much as 10 + degrees timing between pmags, or XXXX's on the left pmag, or large TDA's (timing differences between the pmags) for hours at a time.

I contacted the designer of the EI Commander, we've been in contact for the last 2 years trying to solve these problems. He sends me a new EIC, and of course that wasn't the problem, never has been. So I relay all this data to Brad at Emag. He has no idea what the problems are, again. Of course I get the "check the hoses, check the wiring, check the mag gear, etc, etc." All this was done over and over.

Brad sends me an old pmag with an updated board, ver 40. I installed the ver 40 board in my left pmag, as we all agreed that the left pmag has a data problem. I retime them both and go flying. First thing I see is this huge TDA at lower RPM's. NOT 500 RPM but as high as 1600 RPM! As the engine wound up the TDA's went to normal 2.0, which is the minimum readout.

Again, Ed at EIC sent me another Commander (Best service in the biz) which I knew wasn't the problem, but we tried it anyway.. It wasn't the problem. At this point I had Ed, Bill, Brad and myself running one test after another to see if these anomalies could be traced down. Test after test showed that there was nothing causing this TDA problem other than the pmags. The only difference between the pmags at this point are the board revisions and the software versions. Brad doesn't seem to be concerned enough to help me find the problem. I've asked him to send me matching boards to eliminate the Rev and Ver differences but he doesn't want to. He told me to "Turn off the EIC".

I've been in electronics my whole life, along with being an A&P, a instrument rated pilot since 1980, building Exp aircraft for 12 years and OSH gold. One thing I've learned in all my experience is that any electronic or mechanical problem is most always the beginning of other problems, systemic, like cancer. These 2 pmags have never worked properly since the day they were built. The EIC proves this and my EMS proves this. Whether or not the pmags are firing the plugs does not prove that the pmags are working properly. The last place I want to find the next pmag problem is at 2K feet over the mountains.

I have documented all these EIC readings and EMS graphs, there is no denying these are real and continuous.

I have received PM's on this forum and other forums telling me story after story of pmag failures. As we all know, most people do not like to post on the threads but they want their story to be known. Since I've been outspoken about pmag problems I guess people what me to know what happened to them, too. I fly with other pmag owners and I've seen the same failures and timing shifts. I've installed many pmags and they run. BUT!! The difference between most of these installed pmags and my pmags is I have an EI Commander to monitor what's actually going on, not what other people tell me.

I would no sooner turn off my pmag monitor as I would turn off my engine monitor. You monitor your plane for a reason. These are Vitals. Would anyone fly if they knew number 1 cylinder was 250 degs CHT and number 3 was 500 degs CHT? Why not just turn off the engine monitor and be a mushroom. You have monitors to find small problems before there's a meltdown. If you see nothing wrong you're a happy pilot.

BILL... IF YOU'RE GOING TO TELL MY STORY PLEASE GET YOUR FACTS STRAIGHT!!

If anyone is flying with pmags and no way to monitor what they are really doing than you have no idea what's going on. Just because you're plugs are sparking doesn't tell the whole story. Just because you don't smell burnt oil doesn't mean your engine isn't about to grenade. Just because you don't see the cracks doesn't mean the tail isn't about to come off in the air. We have monitors, and preflight monitors, our eyes, to find problems.

No one using pmags, or any other EI, can tell me they work perfectly just because the engine starts and runs. How do you really know!!

Then load the pics up in Picasa and post a link on VAF. I am also interested in knowing what all these failures are. Thank you.

That's a perfectly valid point, but that premise applies to magnetos, alternators, vacuum pumps, autopilot servos, etc.

Information is powerful, but it needs to be tempered with an end result - does the airplane complete its mission safely and reliably?

Randy,

I added a bold header to separate my comments about your issues from my general comments regarding P-mag installations. Also corrected the 113 vs. 114. When we spoke, I thought you started with 113's, my mistake.

I realized when I re-read it, it sounds like that entire post is about you and what you have found and that is not the case.