O-235 EIS

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Sector95

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Hey there,
My 7ECA has Bendix mags on it, and the left hand impulse mag has a 500 hour recurring AD mandating it's overhaul which is coming due soonish. I was talking with my mechanic today and he mentioned that a SureFly electronic ignition might not be a bad option to a) remove the recurring AD and b) improve efficiency and performance.

Anyone have any opinions on this topic? I don't see a lot of discussion/references on google of electronic ignitions on O-235's, which I find interesting. Makes me wonder if many don't think it's worth it for this engine.
 
As I understand it, the benefit of an electronic ignition is that it has an advance curve programmed in that makes the spark timing better over the full RPM range. What I don't understand is, if the two sparks (one from the magneto, one from the EI) are no longer simultaneous, how does that make the engine more efficient or an overall better running engine? What I know is, when I shut off one mag during the run up, the engine runs worse. Having two sparks that are no longer simultaneous, how is that better? Where in the advance curve is that effect most pronounced?

If you had two EI's, each with the same advance curve and they were both firing at the same time, I can see how that would be better. But one mag and one EI, I don't understand it.

:unsure:
 
I am not familiar with the 500 hour AD. If it is the one about the impulse coupling it no longer applies to most S4 mags.
 
Bob Turner said:
I am not familiar with the 500 hour AD. If it is the one about the impulse coupling it no longer applies to most S4 mags.
Click to expand...

Now that I'm looking through the documentation binder I have, the AD isn't stored in the recurring section of the binder. Last inspection was done in 2011, so I wonder if that inspection ultimately satisfied the AD. Still learning how to disseminate this information.
 
A brief and hopefully adequate explanation is...
Much of the electronic ignition system effeciency is due to the increased intensity of the spark and the timing/introduction of that spark.

The EI is not restricted to the basic static magneto timing point of 20 or 25 or whatever the engine manufacturer spec is. Other variables including RPM and manifold pressure are taken into account by the electronic ignition system. The operator would also observe the "easy start" difference.
This all means the fuel is being ignited at the ideal timing point relevant to the crank angle.
Fuel does not "all explode" in an ideal situation, but rather the burning of the fuel progresses outward from the "flame front" pushing the piston down.
This assumes the correct fuel for the application, as with any engine.
 
Personal experience, I installed a Surefly in my PA28-161 I think about 1300$ it’s been 3 years now. I would never consider another 500 hr inspection so much easer to start hot or cold, smother running motor, and les fuel burn. When I installed it they option of variable timing required 100 LL only no auto gas this may be changed by now.
 
Update on this, my coupled mag (S4LN-21) is still under a 500 hour AD, so turns out this decision is still on the table...

The SureFly is about $1500, but I would also need to find a Slick harness, since mine has Bendix on it right now. I know I shouldn't be, but I'm a little shocked at how expensive those harnesses are, brings the total just above $2k in parts (unless someone knows a good source of a less expensive harness).

The other option is to have my plane go down for 2 or 3 weeks in June or July for a mag inspection, which would be considerably cheaper, I'm sure.

But I'm tempted by the EIS for the reported starting, reduced fuel burn, and slight power improvements. The fact that the plane would only be down for a day instead of weeks is tempting as well.
 
Check the price of the 500 hr inspection, next we just had to replace the cam in a slick and points with less than 300 since inspection. So figure the labor cost to remove and install, down time if your sending it out and compare to new cost of surefly. Then will it increase the value of your aircraft?

Best wishes on the choice
 
Please let us know about the 500 hour AD against the S4. I am running four of them, and about to add two more. I cannot find an AD with a 500 hour requrement.
 
Bob Turner said:
Please let us know about the 500 hour AD against the S4. I am running four of them, and about to add two more. I cannot find an AD with a 500 hour requrement.
Click to expand...

It's only the impulse coupled unit on my engine, the AD number is 05-12-06... But now I'm uncertain again because the AD language I just found says it only applies to a few Lycoming 0-540 engines, if I'm reading it right. I wonder if a previous mechanic got it confused?

RGL Home Page

rgl.faa.gov rgl.faa.gov

Am I reading this correctly?
 
Lots of mechanics get confused. This stuff is now written by lawyers, for lawyers. Without looking to make sure, there was a previous AD that mandated a paper clip check every 500 hours. Easy to do. The new AD supeseded it, and is only applicable to larger six cylinder engines. A lot of mechanics think it applies to all S20 mags.
 
Bob Turner said:
Lots of mechanics get confused. This stuff is now written by lawyers, for lawyers. Without looking to make sure, there was a previous AD that mandated a paper clip check every 500 hours. Easy to do. The new AD supeseded it, and is only applicable to larger six cylinder engines. A lot of mechanics think it applies to all S20 mags.
Click to expand...

Ah that's awesome news, thank you! Can wait to address the inspection until the winter months then 😁
 
You made me look.

The AD is quite clear. The comments include one by folks who were not happy that some would skip the 500 hour inspection of the mag itself - not required by either AD. In fact, as far as I can tell, you can run an S4 until it can no longer start the engine - and people do! They pull them off full of oil.

2005-12-06 supersedes 96-12-07. It eliminates the impulse check for all but Lycoming 540 engines. No lawyer needed; it is flat-out plain English.
 
Bob Turner said:
You made me look.

The AD is quite clear. The comments include one by folks who were not happy that some would skip the 500 hour inspection of the mag itself - not required by either AD. In fact, as far as I can tell, you can run an S4 until it can no longer start the engine - and people do! They pull them off full of oil.

2005-12-06 supersedes 96-12-07. It eliminates the impulse check for all but Lycoming 540 engines. No lawyer needed; it is flat-out plain English.
Click to expand...

First time owner here-- knowing when to trust a mechanic's word and when to question it is still a skill I'm developing. Appreciate your help!
 
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