Precautionary/Emergency Landing due to Pmag Timing Failure

Flying VFR on top today over Pennsylvania my engine started to run hot, and then rough. I saw a hole in the clouds and did sort of a spiral dive to get underneath the clouds and landed at Deck airport (9D4) in Lebanon PA. I did not remember to try switching ignitions until I was taxiing, huge backfires and sputtering with the Right ignition selected. The kind and helpful people at Shearer Aviation loaned me some tools and hanger space, I did compression tests and checked the timing. Sure enough the Right Pmag was way off. I Fedexed both Pmags off to Brad for a quick repair/check/update. I had not send them in for the recall because they were made and serviced before the dates in the bulletin. Maybe this was a mistake. I will update this thread when I know more.

Hans

My passenger had a post on facebook about this within 20 minutes of landing. Seems wrong!

Just a note to others. I am assuming that regardless of your ignition system, you may need to check between the two units inflight if a possible ignition problem develops.

Personally, I would rather run on one good ignition system and get on the ground quickly than have symptoms such as you describe adding to the stress.

Keep up to date on maintaining those ignition systems.

It is a good idea for every RV pilot, even those with two mags, to spend some time creating a "Rough Running Engine" checklist. The time to think about this scenario is on the ground, when you can devote 100% of your brain power to the problem. Come up with a logical set of actions to do if you ever have a rough running engine. Write them down in a check list, and pull it out and use it if you ever have a rough running engine in flight.

Dr Hans if you need anything let me know I am just southof you a little ways at Smoketown, please call if you need anything at all.
Kirk 610-283-2448

I agree 100%

Kevin Horton said:

It is a good idea for every RV pilot, even those with two mags, to spend some time creating a "Rough Running Engine" checklist. The time to think about this scenario is on the ground, when you can devote 100% of your brain power to the problem. Come up with a logical set of actions to do if you ever have a rough running engine. Write them down in a check list, and pull it out and use it if you ever have a rough running engine in flight.

Click to expand...

It was on my mental checklist but not written down. The mental checklist failed in flight.

Hans

Know EP's

This was discussed in another thread. It is critical to have 100% knowledge, 100% of the time for Emergency Procedures.

Here is mine for my Pmag equipped IO360. This will be for rough running, CHT rise.

1) Reduce throttle and turn on auto pilot if you have one. This will slow the advance of the timing and lower the temps.

2) Richen the mixture with a quick twist.

3) Do a mag check with the L/R/Both switch. (whatever type you have) Leave the switch on which ever mag runs smoothly.

4) Monitor the temps for trends use mixture to assist in keeping temps good.

5) Once stabilized and if comfortable doing so, do another mag check and confirm the problem.

6) Depending on where you are, fly on or choose a nearby airport.


Practice this process. Know where everything is, the settings and airspeeds. For me, I reduce the power to fly at 90 kts with a few degrees of flaps. This provides a low power setting but enough airspeed to maneuver safely and keep the temperatures down.

Emergency/Abnormal Checklists

nucleus said:

It was on my mental checklist but not written down. The mental checklist failed in flight. Hans

Click to expand...

Sadly, mental checklists almost always fail in flight. Stress seems to make them evaporate. The accepted procedure is to come up with a couple of "memory items", the things that you need to do now, in your case, something like "Reduce power" and "Establish glide" then get out the checklist and do some troubleshooting.

John Clark
RV8 N18U "Sunshine"
KSBA

In fairness

I don't know of any E/P mags that have failed after the latest updates.

Frank

frankh said:

I don't know of any E/P mags that have failed after the latest updates.

Frank

Click to expand...

I do not have e-mag or p-mag but just read the service bulletin that came out last year on the attachment of the timing sensor to the shaft.

Unless the sensor has the roll pin attach modification, it seems like it would be a good idea to not fly the airplane until this is complied with. The method developed in 2007 is not bullet proof and is the reason for the change last year.

I like the system, based on reading about it, but loss of timing in flight is not acceptable. If nothing else there ought to be a circuit that terminates the unit operation if its timing input exceeds a pre set envelop.

I am not current on PMag issues either but at one time I would have recommended NOT using the blow tube method to set timing. Unconfirmed opinion is that it had a potential to fail so using the "mechanical" method seemed to be what I would have used.

Obviously don't use these comments for anything other than to make sure you have recommended improvements implemented.

A few years ago, I was hesitant to switch between mag settings airborne, but finally did it. This is the second incident that I have heard of with PMags that checking the Left/Right switch may have helped.

Got the Scoop (?) from Brad at Emagair Today

Brad inspected both my pmags today. I was correct in my understanding of the recall bulletin, my pmags did not have the "troublesome" (Brad's term) magnet mounting system and were not subject to the bulletin. There was no failure of the sensor magnet in the pmag that lost its timing. In fact, Brad couldn't find any fault in the troublesome pmag at all. He did say that it did have a max temperature recorded of 217 F which is 17 over the limit, and that may have affected the unit, but he has seen many units with higher temps without problems. He replaced all the electronics in the unit and put in the current sensor magnet system. I plan to mount them up and test fly the plane tomorrow.

frankh said:

I don't know of any E/P mags that have failed after the latest updates.
Frank

Click to expand...

Now you do!

Remember, not all pmags were subject to the sensor magnet bulletin, here is the relevant section:

Date: 9/12/08 (Revised)

Topic: Position Sensor Magnet Mount

Models Affected: Series 113 and Series 114 ignitions shipped or serviced 8/1/07 to 9/6/08 (italics added)

So, just to be clear: Both my pmags were in compliance with ALL the service bulletins when the one lost its timing.

Ron Lee said:

I am not current on PMag issues either but at one time I would have recommended NOT using the blow tube method to set timing. Unconfirmed opinion is that it had a potential to fail so using the "mechanical" method seemed to be what I would have used.

Click to expand...

I agree Ron, that is why I cleared out the software timing and "hard timed" both my pmags the last time they were installed.

Hans

John Clark said:

Sadly, mental checklists almost always fail in flight. Stress seems to make them evaporate. The accepted procedure is to come up with a couple of "memory items", the things that you need to do now, in your case, something like "Reduce power" and "Establish glide" then get out the checklist and do some troubleshooting.

John Clark
RV8 N18U "Sunshine"
KSBA

Click to expand...

Part of my issue was that I was VFR over a pretty solid deck of clouds. The temps dropped nicely once I pulled power and dove through a little hole the clouds. Prior to the seeing the hole I was considering using the autopilot to descend through the clouds, I would have advised center first of course. Having terrain on the GRT was comforting.

Hans

nucleus said:

Brad inspected both my pmags today.... There was no failure of the sensor magnet in the pmag that lost its timing. In fact, Brad couldn't find any fault in the troublesome pmag at all. He did say that it did have a max temperature recorded of 217 C which is 17 over the limit, and that may have affected the unit, but he has seen many units with higher temps without problems. He replaced all the electronics in the unit and put in the current sensor magnet system. I plan to mount them up and test fly the plane tomorrow.
Hans

Click to expand...

Yep. Sounds very familiar. I had Exactly the same experience. I feel lucky to have survived, almost two years ago now.
New question in my household... Are Brad or Tom pilots? Just curious. We've sat and talked to them numerous times and don't have the answer.

You are wasting your time

Ron Lee said:

I am not current on PMag issues either but at one time I would have recommended NOT using the blow tube method to set timing. Unconfirmed opinion is that it had a potential to fail so using the "mechanical" method seemed to be what I would have used.

Click to expand...

nucleus said:

I agree Ron, that is why I cleared out the software timing and "hard timed" both my pmags the last time they were installed.

Hans

Click to expand...

Read the post I made a few months ago.

cguarino said:

...Now as for why the wiring could have been a problem. There are two processors in a Pmag. One is the main processor and the other processes the crank position. In the old firmware, on boot up the main processor powered up and loaded the tables and code. It then sent the timing offset to the crank position processor. This offset was the difference between the "natural timing" of the Pmag and the position when you blew in the tube to set the timing. Once this was done the crank position processor reported the crank position to the main processor including the offset. In the case of a power dip, the main processor is well protected and has logic that causes it to reboot and reload the tables and code. However the crank position processor does not have this same protection and it would occasionally end up with a corrupt offset due to the power dip. This was actually a deficiency in the chip. Tom worked with the chip manufacturer to get the same protection that the main processor has, built into the crank position processor. To fix this problem in the Pmag, Tom rewrote the firmware. Now, when the power dips, the main processor controls the power to the crank position processor and causes it to cycle power and reboot. Additionally, the main processor no longer sends the offset to the crank position processor. The main processor gets the raw crank position from the crank position processor and applies the offset to this raw position. Once set, this offset cannot change until reset. That is why timing the Pmag to the ?natural timing? doesn?t do anything for you. Since this change, I don?t think there have been any lost timing events due to firmware / power dips. Now back to the wire, a bad ground can cause a power dip. I don?t know where Darwin?s ground problem was located but it could have been a player in this scenario.

Click to expand...

Re: Wasting my time

My pmags were older, so I don't think it was a waste of time to "hard time" them. Since you seem to know a lot about the pmags, I would be curious as to your theory why they are loosing their timing? My incident was not isolated. Another forum member sent me a private message who had a timing loss as well.


Hans

Quote:
Originally Posted by cguarino
...Now as for why the wiring could have been a problem. There are two processors in a Pmag. One is the main processor and the other processes the crank position. In the old firmware, on boot up the main processor powered up and loaded the tables and code. It then sent the timing offset to the crank position processor. This offset was the difference between the "natural timing" of the Pmag and the position when you blew in the tube to set the timing. Once this was done the crank position processor reported the crank position to the main processor including the offset. In the case of a power dip, the main processor is well protected and has logic that causes it to reboot and reload the tables and code. However the crank position processor does not have this same protection and it would occasionally end up with a corrupt offset due to the power dip. This was actually a deficiency in the chip. Tom worked with the chip manufacturer to get the same protection that the main processor has, built into the crank position processor. To fix this problem in the Pmag, Tom rewrote the firmware. Now, when the power dips, the main processor controls the power to the crank position processor and causes it to cycle power and reboot. Additionally, the main processor no longer sends the offset to the crank position processor. The main processor gets the raw crank position from the crank position processor and applies the offset to this raw position. Once set, this offset cannot change until reset. That is why timing the Pmag to the ?natural timing? doesn?t do anything for you. Since this change, I don?t think there have been any lost timing events due to firmware / power dips. Now back to the wire, a bad ground can cause a power dip. I don?t know where Darwin?s ground problem was located but it could have been a player in this scenario.

Out of interest

Can you see the max temp the Pmags were subject to by interrogating them through the EICAD software??

Frank

re Max temp via EICAD

frankh said:

Can you see the max temp the Pmags were subject to by interrogating them through the EICAD software??

Frank

Click to expand...

Well, Brad of emagair said that the pmag that lost its timing had hit 217 degrees which is 17 degrees over the limit. When I got them back from emagair there was a 200 degree tell tale sticker on both of the pmags, and I have been checking those since. I think I need to get a row of stickers with lower temps so I can tell how close they are getting.

I suspect I know when it overheated, I was flying in some 100 degree air a couple of weeks before my unit lost its timing.

I haven't used the EICAD software because I don't own a computer with a serial port. Didn't those go away about ten years ago?

Hans

nucleus said:

...I haven't used the EICAD software because I don't own a computer with a serial port. Didn't those go away about ten years ago...

Click to expand...

I tried to "see" my Pmag with my laptop through a USB conversion cable... No luck so far; it can't find the unit. Oh well.

BTW, 200 hrs on my 113 series without a single problem.

Yes, Serial to USB is very Iffy

Yes, my prior experience with USB/Serial converter dongles kept me from even attempting that route...

Hans

frankh said:

Can you see the max temp the Pmags were subject to by interrogating them through the EICAD software??

Frank

Click to expand...

Yes, you can see it via the EICAD software.

However, it has been my experience that it really doesn?t mean that much. The reason is that when you do a quick turn, say for fueling, the engine gets heat soaked and when you power up the P-mags when you are ready to depart, that is usually the temp that gets recorded. As you can imagine, this is usually a high temperature. (We have found the temps to cool significantly in flight, with the blast tubes installed.)

Unfortunately there is no way to reset the high temp mark.

However, our EICommander can display the temperatures real time, as well as display the high temp mark. We hope to release the first batch in the coming weeks.

Charlie,

The issue Darwin ran into had been resolved a year prior to his incident, had he updated the P-mags when the software service bulletin came out he never would have seen the lost timing event he did. IMHO.

Hans? issue is much more troubling to me.

Hans, how long after startup did you notice the problem?

Do you have the blast tubes installed and aimed at the neck of your P-mags?

What wiring setup did you use? (I?m using Bob K?s Z33 schema, which E-mag recommends against.)

(Although I don?t work for E-mag ignitions, I do track E/P-mag issues and try to understand the root cause.)

Toobuilder said:

I tried to "see" my Pmag with my laptop through a USB conversion cable... No luck so far; it can't find the unit. Oh well.

BTW, 200 hrs on my 113 series without a single problem.

Click to expand...

BTW, that's exactly how we communciated with the P-mags for the development of the EICommander.

I have used a dongle with both the EICAD software and an ASCII terminal program.

I certainly don't intend to offend anyone's intelligence here, but I work on a daily basis with USB->Serial converters and they almost all work very well. Most problems I have seen people have with RS-232 is they don't set up the communications properly...i.e...baud rate, stop bits, data bits, rtscts, etc.

Chicken and egg thing?

nucleus said:

Well, Brad of emagair said that the pmag that lost its timing had hit 217 degrees which is 17 degrees over the limit. When I got them back from emagair there was a 200 degree tell tale sticker on both of the pmags, and I have been checking those since. I think I need to get a row of stickers with lower temps so I can tell how close they are getting.
Hans

Click to expand...

Pardon me, but I am a little confused. If the failure causes the engine timing to go way off and makes the engine run very hot, how can the "cause" be a 17 degree "overtemp" of the emag? It would seem that the temperature was a result, not a cause.

John Clark
RV8 N18U "Sunshine"
KSBA

To John

I don't thonk Brad is saying the the 17F overtemp caused the timing issue at all..Just that they put a max spec limit on them..But, there have been other units with higher recorded temps than this and no issues.

The bigger question in my mind is how on earth would the PMags NOT be subjected to a higher temp?

You have an engine running at 375F, you just land, long taxi on a 100F day with an oil temp of 200F and somehow the Pmag is supposed to remain below 200?....How?

Frank

frankh said:

The bigger question in my mind is how on earth would the PMags NOT be subjected to a higher temp?

You have an engine running at 375F, you just land, long taxi on a 100F day with an oil temp of 200F and somehow the Pmag is supposed to remain below 200?....How?

Frank

Click to expand...

That was my question exactly when they stuck one of those silly stickers on the side of my P-mags (that I could fail at will with a temp cycle)! "My name is Scott, and I'm p-mag free for over 300hrs now."

True, but...

frankh said:

I don't thonk Brad is saying the the 17F overtemp caused the timing issue at all..Just that they put a max spec limit on them..But, there have been other units with higher recorded temps than this and no issues.

The bigger question in my mind is how on earth would the PMags NOT be subjected to a higher temp?

You have an engine running at 375F, you just land, long taxi on a 100F day with an oil temp of 200F and somehow the Pmag is supposed to remain below 200?....How?

Frank

Click to expand...

I agree with your question on the temperatures.

The thing that I find disturbing is the lack of diagnosis to provide an answer. Just throwing a few parts at the problem and saying "give it a try" wouldn't make me very happy.

John Clark
RV8 N18U "Sunshine"
KSBA

Well

I think we are at 1 or 2 failures with the latest mods..and yes I am including those 113 series units that apparently were not part of the recall..Mine wern't but I had the upgrades done anyway.

I think this level of failure is acceptable considering the number of units in the feild.

I agree John it is a little disturbing that could not pinpoint the latest problem on the test stand, the issue is there maybe another failure mode lurking out there that has not yet been characterised.

All we can do for now is hope this is a one (or two) off issue.

Frank

Pmag Failure Details

Bill, to answer your questions; it was about 45 minutes into the flight. It was the first flight of the day. I wired them exactly like E-Mag showed in their manual. And yes, the blast tubes were installed per the manual as well, aimed at the neck.

All this was in Pennsylvania BTW, and after I reinstalled the pmags, I flew back to Montana on a very hot day and the engine ran great. Only after I got back did I install a second blast tube to the right one; the one that lost it's timing. So far the tell-tales haven't "told". Of course it generally doesn't get all that hot up here in "Big Sky" country.

Just to give some context to this failure, it was toward the end of a 3 week plane-celebratory tour with my son around the country. We went from Bozeman to Seattle to Oakland to Roswell to Atlanta to Washington DC. So the plane was seeing heat that it had never seen before.

I was a little surprised that the highest temperature recorded was only 217; with all those super-hot fuel stops you would think that it would be higher.

I would like to build a water manometer and test pressures around the cowl to see if there is a good low pressure area in various flight regimes where one could cut some vents. It seems like you could increase exit area without adding drag, and potentially provide a place for all the hot air post-shutdown to go.

Hans

N941WR said:

Yes, you can see it via the EICAD software.

However, it has been my experience that it really doesn?t mean that much. The reason is that when you do a quick turn, say for fueling, the engine gets heat soaked and when you power up the P-mags when you are ready to depart, that is usually the temp that gets recorded. As you can imagine, this is usually a high temperature. (We have found the temps to cool significantly in flight, with the blast tubes installed.)

Unfortunately there is no way to reset the high temp mark.

However, our EICommander can display the temperatures real time, as well as display the high temp mark. We hope to release the first batch in the coming weeks.

Charlie,

The issue Darwin ran into had been resolved a year prior to his incident, had he updated the P-mags when the software service bulletin came out he never would have seen the lost timing event he did. IMHO.

Hans? issue is much more troubling to me.

Hans, how long after startup did you notice the problem?

Do you have the blast tubes installed and aimed at the neck of your P-mags?

What wiring setup did you use? (I?m using Bob K?s Z33 schema, which E-mag recommends against.)

(Although I don?t work for E-mag ignitions, I do track E/P-mag issues and try to understand the root cause.)

Click to expand...

Hans,

Thanks for the info. That seems kind of odd that you would lose the timing in flight like that. Is there any chance the offending P-mag physically slipped/rotated in the hole?

Before you go to all the trouble, wait until you get your EICommander. That has a mode to display the reported internal temps of the E & P-mags.

We are building up our first batch of production instruments and hope to get to the bottom of the list by the end of next month.

With a blast tube on both of mine, the highest operational temperature I saw was around 179 degrees F.

Hi Guys,
These are some of the reasons why I developed the G3i Ignition Interface with magnetos. My ride has a glide slope of a brick and with poor landing visibility in the flare. Ignition failure is not an option. With any ignition system, cross checking, left, right is a must prior to take ?off.
Be Safe
Sincerely,
Thomas Shpakow
www.g3ignition.com

Well

nucleus said:

I would like to build a water manometer and test pressures around the cowl to see if there is a good low pressure area in various flight regimes where one could cut some vents. It seems like you could increase exit area without adding drag, and potentially provide a place for all the hot air post-shutdown to go.

Hans

Click to expand...

The problem is if you increase the net airflow going thru the engine compartment you will add drag.

Its the same as an electrically driven fan..if you neck down the discharge the current flowing to the motor will DEcrease even though you are adding resistance.

if you reduce the resistance (just like opening more exit area) then the fan horsepower (drag through the engine compartment in our case) goes up.

Now I admit if one is just adding a small amount of extra airflow the effect may not be noticable in terms of reduced speed/increased fuel flow.

I'm not sure where one would put an extra vent...above the mags would really be the only place to allow heat to dissipate after shutdown. Trouble is in flight this is a high pressure area (probably) as it is right in front of the canopy.

Now of course we don't know if this in fact a heat related failure?..The 200F looks too low based on simple logic..I might interrogate the EICAD to see if I can see what temps mine have been exposed to.

Mine don't have the blast tubes so that will be a datapoint at least.

Personally I wouldn't go cutting holes at this point, but I certainly understand the nervousness..

Has Brad actually characterised timing shift failures due to excessive temps in any situation as far as you know?

All the best

Frank

Re: Chance of PMag rotating

N941WR said:

Hans,

Thanks for the info. That seems kind of odd that you would lose the timing in flight like that. Is there any chance the offending P-mag physically slipped/rotated in the hole?

Click to expand...

Nope, it was bolted up tight.

Hans

Is it the Temperature?

frankh said:

Now of course we don't know if this in fact a heat related failure?..The 200F looks too low based on simple logic.. (snip)
Has Brad actually characterised timing shift failures due to excessive temps in any situation as far as you know?

Click to expand...

When talking to me he offered it as a possible explanation. He did however point out that he had seen many ignitions with higher recorded temps without any known issues.

Hans

Just a System Procedures Comment

This is just one pilot's comment about a bothersome observation in this thread and it is probably wrong but ...

I cannot fly my airplane, pick an appropriate checklist, read a checklist, implement it in a beneficial way, focus on the problem I am experiencing real time and react to the changing symptoms in a most effective manner. When I get the thing running in an acceptable manner by reducing power, richening the mixture, switching out a mag, switching tanks, etc. and steady state flight is achieved I hold on to what I have and continue to a safe location to land. I don't fly very high usually (12,000 ft max) and would never consider adding a risk like descending because of a symptom that I had overcome with an inflight work around.

I think if you know your airplane you are best served by monitoring your systems for problems that may occur while you fly the plane and navigate full time and take corrective action in direct response to the symptoms/problems when they occur. These are pretty simple, single engine, one person crew airplanes with a short problem response period and I think the procedures should be consistent with that operational environment.

Bob Axsom