gbusterguy
Member
I recently had a problem with my PMAG. Some facts; I have a RV7, Superior IO 360, One Mag and one PMAG serial No. 1775, installed over 2 years ago, I have a standard Bob Knuckles electrical system design, and a B&C alternator.
We were flying at 7,500?, Good Wx, smooth air, lean of peak. Suddenly the engine began running very rough simultaneously the alternator light illuminated. I immediately richened the mixture which didn?t change the roughness. We began to notice an electrical burning smell, not a good sensation. I activated the emergency bus, turn off the master switch and punched in nearest airports in the 430 GPS. The smell dissipated.
We then noticed that the cylinder head temps were in the red. Was this for real or part of an electrical issue? I checked the oil temp., it was above normal. We reduced the power to 42% which was enough to maintain our altitude. The cylinder head temps returned to the green. The engine roughness continued. We considered a mag check but thought it best to leave out that option for fear of making things worse. We pressed on to KUKL, home base at a 130 kt ground speed.
Once on the ground I did a mag check, the engine ran fine on the mag but would not run on the Pmag. We found the connector on the end of the power wire coming off of the alternator had broken after 10 years of vibration and had been arching between the wire and the alternator, thus the elec. burning smell. We found the Pmag timing was out. I was able to retime it following the Emag instructions.
What happened? A clue was found on the Emag website under ?Tips and Tricks.? It says to be sure that your Pmag is off when you charge your battery because the pulsing or cycling of some battery chargers can scramble the timing of the Pmag. It seems that perhaps an electrical pulsing in flight can have same effect on the timing.
Fortunately this happened in good Wx at a relatively high altitude, I have a 4 cylinder EMS and I was flying with another pilot who was a huge help in sorting thing out, and I only had one Pmag.
The Pmag has been sent back to the manufacturer for evaluation. My engine has been inspected for damage by a very competent aircraft mechanic. It has been determined that the rings got hot enough to lose their temper; one cylinder has some scrapes on the cylinder wall. I am replacing that cylinder, rings and all 4 pistons as a precaution. I haven?t given up on EI but I am going to put my mag back on until all this timing business gets resolved.
We were flying at 7,500?, Good Wx, smooth air, lean of peak. Suddenly the engine began running very rough simultaneously the alternator light illuminated. I immediately richened the mixture which didn?t change the roughness. We began to notice an electrical burning smell, not a good sensation. I activated the emergency bus, turn off the master switch and punched in nearest airports in the 430 GPS. The smell dissipated.
We then noticed that the cylinder head temps were in the red. Was this for real or part of an electrical issue? I checked the oil temp., it was above normal. We reduced the power to 42% which was enough to maintain our altitude. The cylinder head temps returned to the green. The engine roughness continued. We considered a mag check but thought it best to leave out that option for fear of making things worse. We pressed on to KUKL, home base at a 130 kt ground speed.
Once on the ground I did a mag check, the engine ran fine on the mag but would not run on the Pmag. We found the connector on the end of the power wire coming off of the alternator had broken after 10 years of vibration and had been arching between the wire and the alternator, thus the elec. burning smell. We found the Pmag timing was out. I was able to retime it following the Emag instructions.
What happened? A clue was found on the Emag website under ?Tips and Tricks.? It says to be sure that your Pmag is off when you charge your battery because the pulsing or cycling of some battery chargers can scramble the timing of the Pmag. It seems that perhaps an electrical pulsing in flight can have same effect on the timing.
Fortunately this happened in good Wx at a relatively high altitude, I have a 4 cylinder EMS and I was flying with another pilot who was a huge help in sorting thing out, and I only had one Pmag.
The Pmag has been sent back to the manufacturer for evaluation. My engine has been inspected for damage by a very competent aircraft mechanic. It has been determined that the rings got hot enough to lose their temper; one cylinder has some scrapes on the cylinder wall. I am replacing that cylinder, rings and all 4 pistons as a precaution. I haven?t given up on EI but I am going to put my mag back on until all this timing business gets resolved.