Light Aircraft Association

Unison have issued two service bulletins SB2-08 and SB3-08 re defective components in some new Slick 4300/6300 series magnetos or older ones fitted with certain new parts. Some 4700/6700 Lasar mags are also affected.

http://www.qualityaa.com/SB2-08_Cams.pdf

http://www.qualityaa.com/SB3-08_Carbon_Brush.pdf

Some comment is on Matronics RV list:

http://tinyurl.com/6ramkd

Steve

Just thought I'd pull this one back to the top of the pile Steve. I've had starting problems on a Lycoming 0-360 engine which was zero houred with new slick mags.(4373 and 4370 with 10 minutes run about 6 months ago). Impulse coupling fitted to the left mag only and giving no spark whatsoever, so I disconnected the wires to make them permanently live and still no spark.

Ultimately I pulled both off the engine to check for the SB's and found that the CB spring on the 4373 was corroded to the extent that there was a permanent set and the points were not closing at all. Maybe worth a look for this corrosion if anybody else has similar mags.

It seems that not being able to fit entire stand alone electronic ignition is only biassed views when the APPROVED systems from the proper makers come up with trouble like this on something that is SO SO reliable!!

EI to replace one mag is quite do-able using ElectroAire or Lightspeed ign systems. Francis is pretty amenable to those via a Mod ( and is even willing to consider some non proprietry alternatives - if well engineered and reasoned via a formal Mod).

This is the first time I've seen this problem and my guess is that a lower grade and cheaper material has been used in the manufacture of these springs form the original drawing specs.

It doesn't mean that mags are any less reliable, it's just that little attention has been paid to them over the years and maintenance has been neglected. I've no doubt that in time all these electronic widgets will start showing the same signs of mechanical and electrical degradation so I'll stick with what I know best.

And the carbon brushes, I would be really fed up if I had bought a pair of these and faults occurred. The idea of approval is that the company has really strict production standards and the products do not fail so soon after being used.

Automotive EIs are incredibly reliable with no maintenance for many x0,000's miles - literally fit & forget. I doubt many of us are driving cars (other than classics) with contact breakers any more so in a way EI is what we are now familiar with/know best.

I think mags' advantages are really only their independance from the a/c electrical system (particularly if one does not exist!) and for that reason alone, I'd keep one on my a/c - otherwise they are really ancient technology with far too many moving parts for my liking (and not as fuel efficient/environment friendly as is possible) .

That'll be the Mag that gets you over the fence you're sitting on then Steve?

With a dog in one garden and the missus in the other, the fence is by far the safest place!

Guess I am fence sitting to get the best of both worlds - the mag as an insurance but that is effectively pretty redundant (ie sparking after the EI in most instances ie at a std fixed 24 deg BTDC) and the EI providing the earlier correct advance spark point to give the power & economy etc appropriate for the engine conditions/altitude at the time - the nice fat spark it gives is an added bonus.