Trouble shooting mag check.

[Christopher Bolivar]

I have a trouble shooting questions when it comes to failing an RPM check. My left mag failed during a run up. I bought new plugs for the bottom and passed on the RPM check. Next flight out the new plugs failed during the check. I bought new plug wires and it did not solve the problem. I had the new plugs bench tested and they were all good. Then I swapped the old plugs and put them on the bottom and put the new plugs and put them on top. Now the right mag failed the run up. So the problem went from left to right. Now I did barrow four plugs from a friend and swapped them out with the new plugs that are on top now and both mags passed during run up. I am having the timing checked soon and I currently have slick mags with about 300 hours on them. Any thoughts since the new plugs checked good on the bench test?

Oh the plugs are Tempest on a C-90-f engine.

 

[Steve2618G]

 

[AKJurnee]

 

[Christopher Bolivar]

 

[Christopher Bolivar]

 

[Sunderland]

 

[bob turner]