Magneto Confusion

[Frank Brunot]

PA-30 in for it's annual, and I was going to do the 500 hour mag check/overhaul.

My problem is I have SLICK Model 4373 mags on my engines, when the Lycoming IO-320-B1A manual calls for Bendix S4LN-21 mags.

1) Are these two mags interchangeable?

2) Are the Slicks even legal on an IO-320-B1A engine?

If the answers are NO to the above, are there any special procedures in going back to Bendix mags?

If YES, why would one change from Bendix to Slick?

[farmer]

The Slicks are legal. See stc somewhere in your records. Years ago Slick did a marketing trick to get people to change to Slicks.

[Kristin Winter]

Slicks are legal as long as you don't have a turbo Twinkie. Lycoming Service Instruction 1443 is the controlling document here.

The Slicks have usually been less expensive than the Bendix which is why engine shops often install Slicks during overhaul. The Bendix is a better mag, IMO.