N941WR
Legacy Member
I’m throwing this out there to see if others have experienced similar issues.
As the manufacture of the EICommander I answer a lot of questions (both on and off line) regarding issues with P-mags.
A month before my Condition Inspection was due my EICommander started giving me some odd readings regarding the health of my ignition. However, the P-mags were timed correctly, they were advancing in unison, they were both running the same configuration, the CHT’s & EGT’s were “normal”, and the engine just felt fine.
After going through every test, connection, and whatnot, I decided to change out the NGK BR8ES spark plugs with a new set. What the heck, I typically change them at every Condition Inspection, so doing it a month early was no big deal. Besides, they had about 105 hours on them. (I know, it was a slow year for me.)
The new plugs were gapped for .032 and installed. The old plugs were checked and the gaps were right at .032 and they looked fine. I could find no issues of any kind.
After changing them out, the EICommander reported all was fine.
Brad at Emag Ignitions, told me “There is some anecdotal evidence” that the plugs go bad at around 100 hours.
In discussing this with my partner in the EICommander, who flies a rotary powered RV-6A, I was sent this little gem:
This is just food for thought. At less than $20 for a set of eight plugs, I now replace them all at 100 hours. Because of the cost involved, I don’t even bother with platinum plugs.
As the manufacture of the EICommander I answer a lot of questions (both on and off line) regarding issues with P-mags.
A month before my Condition Inspection was due my EICommander started giving me some odd readings regarding the health of my ignition. However, the P-mags were timed correctly, they were advancing in unison, they were both running the same configuration, the CHT’s & EGT’s were “normal”, and the engine just felt fine.
After going through every test, connection, and whatnot, I decided to change out the NGK BR8ES spark plugs with a new set. What the heck, I typically change them at every Condition Inspection, so doing it a month early was no big deal. Besides, they had about 105 hours on them. (I know, it was a slow year for me.)
The new plugs were gapped for .032 and installed. The old plugs were checked and the gaps were right at .032 and they looked fine. I could find no issues of any kind.
After changing them out, the EICommander reported all was fine.
Brad at Emag Ignitions, told me “There is some anecdotal evidence” that the plugs go bad at around 100 hours.
In discussing this with my partner in the EICommander, who flies a rotary powered RV-6A, I was sent this little gem:
Bill, having read about the ignition problem you refer to, I may have something to contribute.
As you know, I and most of the folks who fly rotary engine powered aircraft use regular automobile spark plugs. Most folks fly using auto fuel, but I and a few others fly almost entirely using 100LL av gas. What I and others have discovered is that after approx 100 hrs (it varies) on Av gas, the engine develops what we call "SAG" (Sparkplug Attention Getter).
The engine will take on a different note, rpm will drop and (in the early stages) after a couple of minutes things return to normal. The interval and duration of the SAG continues to increase - this can be quite disconcerting and lead folks off on wild goose chases trying to fix fuel and other problems.
We had one technical analysis which included cutting open the offending plugs - it appears that after 100-120 hrs running on Av gas the lead in the fuel gets deposited on the ceramic cone, also it appears that the continuous (hour after hour) of high engine rpm stress internal bonding of the auto spark plug components and leads to deteriorating spark performance. The only cure that we have found thus far is to replace the auto plugs.
So any time a new rotary flyer reports those types of symptoms, we tell them to change their sparkplugs.
Now without use of 100LL, those folks using auto gas generally get a several hundred hours or more - this SAG pertains to use of auto plugs with 100lL
FWIW
Ed
This is just food for thought. At less than $20 for a set of eight plugs, I now replace them all at 100 hours. Because of the cost involved, I don’t even bother with platinum plugs.
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