Van's Air Force
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P-mags, E-mags, EI discussion
- Thread starter jbDC9
- Start date
frankh
Well Known Member
NOT odd
This is a sign of a well balanced FI system, the rough running is apparently due to the mixture becoming unbalanced between the cylinders. If the FI nozzles are closely balanced the flame will simply go out.
I still haven't balanced mine yet but they are fairly close and the engine is pretty smooth just getting lumpy at the point of quitting.
Frank 7a
This is a sign of a well balanced FI system, the rough running is apparently due to the mixture becoming unbalanced between the cylinders. If the FI nozzles are closely balanced the flame will simply go out.
I still haven't balanced mine yet but they are fairly close and the engine is pretty smooth just getting lumpy at the point of quitting.
Frank 7a
frankh
Well Known Member
Another P mag issue
I am sad to report that another PMag has thrown a wobbly.
If you remember we believe mine was the first unit to "lose its timing" and cause detonation issues. Then a second airplane made a forced landing.
That was eventually resolved and blamed on the "Blow in the tube" method. There were some upgrades and the issue resolved.
I had a couple of additional minor glitches on my Pmag and Brad replaced my Pmag for what I believe was a new unit.
That pmag has been running for 65 hours and today on the second flight of the morning the engine ran extremly rough on the Pmag.
The timing has retarded itself on the PMag by 9 teeth (about 26 degrees assuming its 122 teeth on the flywheel).
Needless to say I am very reluctant to just retime the Pmag and go flying as there is no way to know if it will suddenly move again.
It is possible I guess the the Pmag was one of the units that had not had the firmware upgrade, I will have to wait till Tuesday to find out.
Needless to say this is a very sad event and I am begiining to wonder if this thing is going to strand me somewhere far from home or destroy my engine one day?
I am fourtunate the ignition retarded itself this time, not advanced.
As far as I know the Emag has been perfectly reliable.
Frank
Grounded for the weekend.
I am sad to report that another PMag has thrown a wobbly.
If you remember we believe mine was the first unit to "lose its timing" and cause detonation issues. Then a second airplane made a forced landing.
That was eventually resolved and blamed on the "Blow in the tube" method. There were some upgrades and the issue resolved.
I had a couple of additional minor glitches on my Pmag and Brad replaced my Pmag for what I believe was a new unit.
That pmag has been running for 65 hours and today on the second flight of the morning the engine ran extremly rough on the Pmag.
The timing has retarded itself on the PMag by 9 teeth (about 26 degrees assuming its 122 teeth on the flywheel).
Needless to say I am very reluctant to just retime the Pmag and go flying as there is no way to know if it will suddenly move again.
It is possible I guess the the Pmag was one of the units that had not had the firmware upgrade, I will have to wait till Tuesday to find out.
Needless to say this is a very sad event and I am begiining to wonder if this thing is going to strand me somewhere far from home or destroy my engine one day?
I am fourtunate the ignition retarded itself this time, not advanced.
As far as I know the Emag has been perfectly reliable.
Frank
Grounded for the weekend.
PMag
Frank,
Can you give more detail, please?
How was the timing changed?
Did it "physically" change? Shaft slip somehow?
Or was the PMag electronically changing the timing?
Are you running the PMags in "fixed" or "variable" timing mode?
I'm building the panel and haven't flown yet.
I have two PMags and am starting to get a little "antsy" about these things.
Thanks!
frankh said:
Frank,
Can you give more detail, please?
How was the timing changed?
Did it "physically" change? Shaft slip somehow?
Or was the PMag electronically changing the timing?
Are you running the PMags in "fixed" or "variable" timing mode?
I'm building the panel and haven't flown yet.
I have two PMags and am starting to get a little "antsy" about these things.
Thanks!
frankh
Well Known Member
Pmag
The unit did not physically shift as far as I know, For it to shift that much the HT leads would have been twisted. I believe the unit is bolted in the same place it was when I installed it.
I did not use the blow in the tube method, instead I used the timing it came with and set it up that way.
Timing is in the variable mode.
Now it is possible the unit I got did not have the latest firmware fix but it should have considering how it was shipped after the detonation issues a while back.
Frank
The unit did not physically shift as far as I know, For it to shift that much the HT leads would have been twisted. I believe the unit is bolted in the same place it was when I installed it.
I did not use the blow in the tube method, instead I used the timing it came with and set it up that way.
Timing is in the variable mode.
Now it is possible the unit I got did not have the latest firmware fix but it should have considering how it was shipped after the detonation issues a while back.
Frank
frankh
Well Known Member
Yes but....
If by har timing you mean using the factory default...Well thats exactly what I did with this unit...And it has shift 25 degrees or so from that timing.
The question is why?...And I sincerely hope emag doesn't come back with what they always say..."it tested fine on our test stand"
In other words, issue not found and no solution either.
We shall see
Frank
If by har timing you mean using the factory default...Well thats exactly what I did with this unit...And it has shift 25 degrees or so from that timing.
The question is why?...And I sincerely hope emag doesn't come back with what they always say..."it tested fine on our test stand"
In other words, issue not found and no solution either.
We shall see
Frank
I have used an hour or so reading through all this. I thought mags looked complicated and prone to errors, but no i'm not so sure anymore. One thing that comes to mind is introduction of new failure modes in new equipment. Another fact of life is that old and trusted technology is old and trusted because of all things that CANNOT happen to them. Consequently since those failure modes never happends, they are forgotten. Nevertheless, when those old and trusted technologies were developed and put into systems, all possible failure modes were considered by the engineers, because that is how and why equipment get old and trusted in the first place.
In the oil and process industry it's mandatory to do a so called HASOP (Hazard Operation) on every bit of equipment, especially when introducing new things. The idea is to get together and go through all failure modes that possibly can happend in a system, and find solutions, changes and procedures so that the integrity of the system is intact in case of a mishap. I allways thought that this was a thing copyed directly from aviation, but now I am not so sure about that either
The Ducati CDI system on the Rotax engines has proven to be one of the most reliable produced (if not THE most reliable ever). Does anyone know if this has been installed on the Lycoming ? Does it exist any kits for this?
In the oil and process industry it's mandatory to do a so called HASOP (Hazard Operation) on every bit of equipment, especially when introducing new things. The idea is to get together and go through all failure modes that possibly can happend in a system, and find solutions, changes and procedures so that the integrity of the system is intact in case of a mishap. I allways thought that this was a thing copyed directly from aviation, but now I am not so sure about that either
The Ducati CDI system on the Rotax engines has proven to be one of the most reliable produced (if not THE most reliable ever). Does anyone know if this has been installed on the Lycoming ? Does it exist any kits for this?
Martin Sutter
Well Known Member
Frank - you stated that the p-mag was installed with the timing set as it came from the factory. Does that mean you did not blow in to the tube at all? If that is the case the unit still had a "stored" timing offset in it. In order to be assured that you are using the built-in or "native" timing value you must blow in to the tube once to erase any stored values. You should then get a fast blinking red LED indicating that all stored values have been erased. After that turn the power off, then back on and find the green LED for manual timing. Brad explained to me that they check every unit on the bench and time it with the blow method to see that it works propery. After that they do not erase the just stored offset. If you subsequently install the unit without erasing that value it is not working off native index. The timing procedure outlined in the manual states that in order to employ the quick timing method you must blow in to the tube twice. The first time to erase any stored value (blinking red LED), the second time to set the new timing (steady green LED)
Martin Sutter
building and flying RV's since 1988
Martin Sutter
building and flying RV's since 1988
Ron Lee
Well Known Member
Thanks Martin
That may help a lot of people. I know of another soon to fly plane here with two P-Mags and my suggestion to them was to use the native position and eliminate any possible issues like we saw with the "forced" landing a few months ago. I was not aware that you had to clear the "blow" setting in order to use the native method.
That may help a lot of people. I know of another soon to fly plane here with two P-Mags and my suggestion to them was to use the native position and eliminate any possible issues like we saw with the "forced" landing a few months ago. I was not aware that you had to clear the "blow" setting in order to use the native method.
Kevin Horton
Well Known Member
In the type-certificated portion of aviation, new products, or modifications to existing products, must meet certain design requirements before they can be installed on aircraft. Generally speaking the failure modes of the product must be identified, as well as the severity of the hazard created by that failure. If the hazard is severe, the probability of the failure mode must be assessed as quite low.SvingenB said:In the oil and process industry it's mandatory to do a so called HASOP (Hazard Operation) on every bit of equipment, especially when introducing new things. The idea is to get together and go through all failure modes that possibly can happend in a system, and find solutions, changes and procedures so that the integrity of the system is intact in case of a mishap. I allways thought that this was a thing copyed directly from aviation, but now I am not so sure about that either
But, in the amateur-built portion of aviation, there are no such design requirements. We have many new companies producing great new products, but many of them cut corners to reduce costs. One corner they may cut is a detailed design review to determine failure modes, effects and probabilities. Users of products that perform critical functions (such as ignition systems for single-engine aircraft) ought to think twice about purchasing unproven products, unless they have very good reasons to believe that the manufacturer has done a proper job of design and testing. It is all well and good for the manufacturer to fix problems that are seen in service. But it is far better to have done a proper job during the design and testing, so that these problems never make it into the field.
frankh
Well Known Member
Thanks Dan and Martin
Dan,
Yup I fully understand where your coming from. I too am at the point of hoping something obvious has gone wrong and can be corrected. The Emag boys have worked incredibly hard to make a wonderful product and I thought all of the issues had been worked through. With all the bug fixes the units have performed perfectly for a while now and all of a sudden something hapened. If I'm just unlucky and its a simple fix then sure I'll continue with the Pmag....I have to balance that however with so far there have been a bunch of issues where they put it on the test stand and found nothing wrong...If that happens again (and it hasn't happened yet) I won't be happy.
Martin,
Hmm, so I may have had a stored value in there that may have shifted?
So that raises 2 questions...Does that mean the blow in the tube method STILL desn't work. or does that mean this unit does not have the the latest bug fix in it?
Guess more to talk to Brad about on Tuesday...
Frank
Dan,
Yup I fully understand where your coming from. I too am at the point of hoping something obvious has gone wrong and can be corrected. The Emag boys have worked incredibly hard to make a wonderful product and I thought all of the issues had been worked through. With all the bug fixes the units have performed perfectly for a while now and all of a sudden something hapened. If I'm just unlucky and its a simple fix then sure I'll continue with the Pmag....I have to balance that however with so far there have been a bunch of issues where they put it on the test stand and found nothing wrong...If that happens again (and it hasn't happened yet) I won't be happy.
Martin,
Hmm, so I may have had a stored value in there that may have shifted?
So that raises 2 questions...Does that mean the blow in the tube method STILL desn't work. or does that mean this unit does not have the the latest bug fix in it?
Guess more to talk to Brad about on Tuesday...
Frank
Ron Lee
Well Known Member
Good things to consider Frank
The post about identifying failure modes is also important. The forced landing apparently had the engine run fine after the landing (and presumed engine shutdown). Yet the same P-mag problem occurred a week or so later.
In your case, the unit might test fine.
A FADEC equipped RV-7A is basically totalled from an off-field landing yet the engine was reported to have run fine when tested.
With blow tube equipped P-mags, personally I would want it timed using the native method with no possibility of it changing to another timing setting in flight. Martin stated that you have to clear the factory set blow tube setting to do this but is it 100% certain that even if that is done that there is one and only one timing setting? Can the P-mag folks state that there are no failure modes (software, electrical, etc) that would cause a shift in timing in flight?
Martin, one question. I assume that after the P-mag problem you ran only on the Emag to get back home. And that the engine ran fine. Is that correct?
The post about identifying failure modes is also important. The forced landing apparently had the engine run fine after the landing (and presumed engine shutdown). Yet the same P-mag problem occurred a week or so later.
In your case, the unit might test fine.
A FADEC equipped RV-7A is basically totalled from an off-field landing yet the engine was reported to have run fine when tested.
With blow tube equipped P-mags, personally I would want it timed using the native method with no possibility of it changing to another timing setting in flight. Martin stated that you have to clear the factory set blow tube setting to do this but is it 100% certain that even if that is done that there is one and only one timing setting? Can the P-mag folks state that there are no failure modes (software, electrical, etc) that would cause a shift in timing in flight?
Martin, one question. I assume that after the P-mag problem you ran only on the Emag to get back home. And that the engine ran fine. Is that correct?
frankh
Well Known Member
ONe thing
I intend to check this pm is if the timing has gone back to its native setting...
I.e clear the current timing (red flashing LED), switch it off and it should be set to native.
As I have marked the flywheel with the firing point it should show the green LED at the same position.
It might save shipping it back to TX...
Frank
I intend to check this pm is if the timing has gone back to its native setting...
I.e clear the current timing (red flashing LED), switch it off and it should be set to native.
As I have marked the flywheel with the firing point it should show the green LED at the same position.
It might save shipping it back to TX...
Frank
gmcjetpilot
Well Known Member
Mag's fail to
Magnetos also fail. That is why there are two.
Just remember if you have a problem to cycle the ignition switches one at a time, so if one is misfiring so badly as to cause the engine misfire, you might isolate the problem.
How two independent ignitions fail is a mystery? Isn't it
Magnetos also fail. That is why there are two.
Just remember if you have a problem to cycle the ignition switches one at a time, so if one is misfiring so badly as to cause the engine misfire, you might isolate the problem.
How two independent ignitions fail is a mystery? Isn't it
Kevin Horton
Well Known Member
Well, if both ignition systems have software that allows the intial timing to be set by sending pulses in the MP line, and that software is not well written, then changes in the MP in flight can cause the timing to change in a bad way. Both ignition systems are seeing the same MP flucuations, so a single software fault can cause the timing on both ignition systems to go screwy at the same time.gmcjetpilot said:
In this case, you may have two ignition systems, but you don't have two independent ignition systems.
Of course, supposedly, this software fault is not present in the latest configuration. Hopefully.
frankh
Well Known Member
What we know so far
I confirmed the timing was were it was when I shut down yesterday (some 20 odd degrees retarded).
Then I reset the unit back to its native timing (blow in tube once, flashing red LED, shut off power, reapply power)
The timing had moved to a completly different spot...like 133 degrees retarded.
In other words the Pmag did not fail in a way to find its native timing, but to some other spot...Maybe this is more indicative of something having "slipped" within the unit as dan suggested.
Either way I pulled the Pmag out and boxed it up ready for shippng on Tuesday as clearly this needs to be stripped down and investigated.
Thanks for your thoughts guys.
Frank
I confirmed the timing was were it was when I shut down yesterday (some 20 odd degrees retarded).
Then I reset the unit back to its native timing (blow in tube once, flashing red LED, shut off power, reapply power)
The timing had moved to a completly different spot...like 133 degrees retarded.
In other words the Pmag did not fail in a way to find its native timing, but to some other spot...Maybe this is more indicative of something having "slipped" within the unit as dan suggested.
Either way I pulled the Pmag out and boxed it up ready for shippng on Tuesday as clearly this needs to be stripped down and investigated.
Thanks for your thoughts guys.
Frank
tonyjohnson
Well Known Member
Regarding Kevins observation about the possibility of both Pmags being affected my a change in MP...
This may be a good reason to have one Emag and one Pmag. If the fault developed, the Emag would be unaffected. One thing to be certain on the emergency procedures checklist would be to turn off the Pmag.
This may be a good reason to have one Emag and one Pmag. If the fault developed, the Emag would be unaffected. One thing to be certain on the emergency procedures checklist would be to turn off the Pmag.
frankh
Well Known Member
Not sure
How you get there Tony?
Both the Emag and the Pmag have the same manifold pressure measurement and both can be set using the "blow in the tube" method.
If there is a problem with the tube method (and it does NOT look like my Pmag failed this way) then both the Emag and the Pmag could be equally affected.
Am I missing something??
Frank
How you get there Tony?
Both the Emag and the Pmag have the same manifold pressure measurement and both can be set using the "blow in the tube" method.
If there is a problem with the tube method (and it does NOT look like my Pmag failed this way) then both the Emag and the Pmag could be equally affected.
Am I missing something??
Frank
E-Mag Failure
I have an RV-8 with 220 hours on an IOX-370. I have dual E-Mags and have had 4 Left Mag Failures. The first one was due to not having Blast tubes installed. I am open to suggestions but I would like to install a Bendix or Slick Mag on the Left side. Looking for a dealer that has the mags that still use auto plugs.
Pat Keating
RV-8 82584
I have an RV-8 with 220 hours on an IOX-370. I have dual E-Mags and have had 4 Left Mag Failures. The first one was due to not having Blast tubes installed. I am open to suggestions but I would like to install a Bendix or Slick Mag on the Left side. Looking for a dealer that has the mags that still use auto plugs.
Pat Keating
RV-8 82584
N941WR
Legacy Member
You are replying to a 12 year-old thread. There was an issue that was resolved years ago.
N941WR
Legacy Member
Pat, give me a call. Check your PM's for my number.
