LASAR Left Mag Failure

I'm still unable to post a photo via picassa

The mag shaft is completely sheared at the entrance into the mag housing.
It happened just after takeoff on downwind, with the symptom being a very short decrease in RPM (constant speed prop) and then a return to normal. My passenger (a very experienced pilot) wondered if it might have been a slug of water in the fuel. I then noticed the LASAR failed light on and returned to the airport and landed. It never ran rough but I did a quick mag check on the ground and when the switch was turned to "L" the engine would have died if I didn't quickly go back to both.

Any thoughts on this would be appreciated.

Jeremy Constant

photo posting challenged...

...I'll figure it out after I get some sleep

As a teaser, the shaft on the mag was completely sheared.

Jeremy

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I had exactly what you described (broken internal shaft) twice. The Lasar controller simply thinks the engine has stopped running. Those two failures came after some other electronic problem in the left mag. Three failures in 700 hours was a bit much. The momentary (1/4 second) power loss when the mag shaft breaks gets one's attention.

There is some sort of design flaw (I got Unison, at that time, to admit as much) in the internal shaft. It happened to me at around 300 and 700 hours TTSN. I'm speculating, but there is likely some sort of torsional resonance going on.

The third failure (second broken shaft sort) was when I was 1200 n.m. from home. I put a brand new one on out on the ramp, flew it home, and pushed it into the hangar. I ripped every last piece of that system off my plane, and have been flying with a dual Lightspeed, direct crank pickup, ever since. No problems whatsoever in the last 500 hours.

LASAR Left Mag Failure


After takeoff, on downwind, my rpm sagged momentarily. It behaved as though there was either a slug of water in the fuel or I had turned off the mags and then back on as quickly as I could. The engine ran smoothly after the initial sag. I returned and landed and did a quick mag check. The left mag was dead. This is a LASAR system.

The only troubleshooting I could think to do without taking the mag off was to check the mag switch with a DVM. It was behaving correctly. I pulled the left mag and was alarmed to see that the shaft was sheared very cleanly at the point where it enters the housing.







I emailed pictures to my engine builder. He said he had never seen a failure like this. His guess was that either the shaft seized in the mag housing and the engine continued to drive the mag and something had to give and that was why the shaft broke or a foreign object caused an interference fit between the drive gear and the driven gear. He then suggested that I contact the Slick representative at Champion Aerospace, who are now the owners of the LASAR system. He assumed that they would probably want to see this.

I contacted the Slick representative. After emailing him the pictures, he called and said he had only seen 3 examples of this kind of failure, all of them on a specific small bore Continental model and had never seen one on a Lycoming. After very lengthy discussions which I won't go into, my take-away impression is that Champion wants to be rid of the LASAR system as soon as possible and has no intention of supporting it in any way, other than to get rid of their remaining inventory at what they acknowledge as exorbitant prices. I believe they are pricing them to prevent further sales except to people that have no choice, for whatever reason. Once the parts are sold, you're on your own.

One aspect that I'm still considering is that of what to replace the ignition with. "Vibration" was posed as a possible culprit for the shearing of the mag shaft by Champion. I was leaning towards E mag/P Mag but as my builder pointed out, if there is a vibration issue (which may or may not be a red herring) then something like the LightSpeed ignition doesn't have anything in the accessory section. He has seen many trouble-free installations of Lightspeeds with high compression pistons and a variety of props. He has also seen many trouble-free installations of the Emag/PMags. I'm still struggling with the replacement decision...

I am upset about the situation, but very satisfied with the help I'm getting from my builder, not so much with Champion. I don't want to name my builder or the Champion representative without their permission.

I felt the community should know of one more LASAR data point.

Thanks for the opportunity to get this off my chest.

Alex: do these photos show the same kind of failure as you experienced?

Jeremy Constant

I have a friend that also had a shaft failure on his sensor, timing went way advanced and could have trashed his brand new engine but he caught it in time. He jerked that system out and Unison traded him even for two mags!

The power if the Internet proves that this is a well known problem and the rep that said it is not is not being truthful or is not informed. This is a design problem and most likely there is nothing about your engine that caused this.

Jeremy, I do not know what the broken shafts on mine looked like. I sent both of them to (then) Unison, and upon bugging them, learned that the shafts were somehow broken internally. There was discussion of the mags being covered under warranty, so I didn't disassemble to have a look. They were covered, btw, so I personally had a acceptable financial experience with regard to the three failures. I suspect those days are long ago history.

I do not believe that some engine related vibration causes these problems. Again, I would speculate it is a torsional vibration mode within the mag, or some internal misalignment. Something is causing cyclic stresses leading to fatigue failures.

I learned that there was indeed some sort of redesign contemplated/happening to correct this, but it is something like 5 or 6 years ago that I learned this. I do not know if it happened or not. The rep may indeed only know of 3 shaft failures, but it is likely not because only three happened.

Good luck with deciding what to replace the system with. I personally really like the "no moving parts" aspect of the direct crank pickup LS system. The magnet system was initially too finicky, but I understand it might be better now. Much banter on these forums about EI systems, it'll keep you busy the whole weekend!