Dual P-MAG Reliability in 2017

[Carl Froehlich]

Originally Posted by Captain Avgas

SNIP

I have a LightSpeed Plasma 11 on one side (magneto on the other....I'm with Vic Syracuse on this). I'd have to think very seriously about publicly whinging about a fault in my EI on VansAirforce and then going cap in hand to Klaus at some time in the future for support. SNIP

I have recent personal experience on this. I'm helping a budding who has dual Lightspeed ignitions and he ordered (and paid for) a replacement coil from Klaus. Klaus would not mail the coil to me. He mailed it to my buddy and then he had to mail it to me.

The good news is both ignitions are working.

Carl

[Toobuilder]

Originally Posted by DanH

...Recall wires can fail open, or shorted. I typically make a list with each wire represented and think about both open and grounded failure modes, ignoring the probability of failure, and initially only considering what happens if it does fail...

You bring up a good point that this fault analysis is a great tool for uncovering vulnerabilities in a system. But it seems to me that many people don’t understand that this is but one step in the process. Many people think that vulnerable = unacceptable, and the preferred way to fix that is with redundancy. Many times, the “fix” is actually ensuring that the probability of failure is below the acceptable threshold through a robust installation. One grounded wire can take out a magneto, for example. So is it better to add another ignition or protect that wire from a short?

The point I’m trying to make is that we spend a lot of time on this forum searching for the perfect redundancy scheme, but not nearly enough time executing the basics of the system. Wiring, including connectors, are phenomenally reliable when designed and installed correctly. “Wiring” is significantly more reliable than the components they service, yet we see a lot of electrical issues in the E-AB world. Certainly much more so than in cars or spam cans. The problem, as it turns out, is “us”.

Talking about the latest magic scheme/gadget to ensure airliner levels of dispatch reliability may be sexy, but maybe we should spend some time learning how to terminate and route wires first?

[rv6ejguy]

We get the redundancy/ reliability question often in our business during initial emails or phone calls with our customers. Some are wary of total electronic dependency, others are ready to ashcan all the legacy fuel/ ignition bits and step into the new world.

In the end, anything can fail and you're still in a single engined aircraft where the engine itself is a single point a failure. People seem to think that engine is infallibly reliable. It isn't. We all know or have heard of someone who's had one fail mechanically. Well designed electronics are many times more reliable than aircraft engines in my experience since there are no moving or wearing parts (remember our test ECU with 145,000 hours on it). I don't know of a single Lycoming engine which has gone even 1/20th that time without being touched.

As someone else posted here, there is always some risk on each flight and everyone has a different level of risk they will accept. Some happily fly single engined at night over the mountains, others would never accept that risk. If you can't accept ANY risk, best to stay home on the ground.

We can mitigate many risks by doing good work on our planes and making good decisions on the ground and in the air.

[Chkaharyer99]

Anyone out there running one Pmag and one SDS CPI EI?

Are these two devices compatible together on one lycoming engine?

If the Pmag failed or misbehaved in flight as described in some posts would it/could it adversely effect the operation of the SDS CPI EI?

Anyone else notice that the CEO of SDS participated in this thread? I did. I appreciate hearing from the MFG of products I'm considering.

Anyone notice the conspicuous absence of representation from Pmag?

Nope, nada, nothing. Just saying.

[N941WR]

Originally Posted by DanH

...

Pin 1: I think you just stated the system works with this one open. If shorted is normal and open doesn't matter, the logical question becomes "Why is it there?" Back up for case ground to engine block?

I can't answer with certainty because I didn't design the P-mag but I believe you are correct that it is a backup ground. It is really needed for communication through the serial port.

Originally Posted by DanH

Pins 2 and 3: Without an EIC, an open shifts timing aprox 5 degrees advanced. Field experience says that's probably not critical at WOT with 100LL fuel, just higher CHT. I have no idea what the result might be by shorting either 2 or 3 to ground, with or without the EIC. How does the EIC drive a timing shift with these wires?

Since 2 and 3 are a serial port, I don't believe it would impact anything in flight. We have shorted them when developing the EICommander with no impact to out test P-mags.

As for what would happen if a break happened in flight, the P-mag only checks for the jumper upon startup, after that it never checks again. So, if you start up on the A memory location, it will continue on that configuration until shutdown.

If you have loaded a custom configuration via Emag's EICAD program or our EICommander, you are running off of the B memory location and when running without the EICommander, there is no jumper and when running with the EICommander, you can disconnect it and you will continue to run off of whatever configuration you have loaded, be it the A, B, or a custom configuration.

Originally Posted by DanH

Pin 4: Obviously a short kills the mag, like any mag.

Correct.

Originally Posted by DanH

Pin 5: An open above 800 RPM or so is no issue; that's the whole point of the internal generator. What about a short to ground?

An internal sort to ground would probably kill the generator; however, it would continue to fire, if ship's power is available.

Originally Posted by DanH

Pin 6: Tach lead. Assumed to have no effect on the P-mag alone, open or shorted. Does the EIC use the tach signal for anything other than an RPM display?

Correct and they list it as a "courtesy (optional) connection".

Originally Posted by DanH

A perfectly reasonable answer. It's an extension of the above; list the possible failures, and consider the result of each. Here the result of all failures is the ignition doesn't work, but the flight continues, as we have two of them.

This comes down to individual choice. How much control does one want of their ignition timing map and what type of back up system do they want.

As we have seen in this thread, there are many difference of opinion and risk tolerance. All good things.

[rv6ejguy]

Originally Posted by Chkaharyer99

Anyone out there running one Pmag and one SDS CPI EI?

Are these two devices compatible together on one lycoming engine?

If the Pmag failed or misbehaved in flight as described in some posts would it/could it adversely effect the operation of the SDS CPI EI?

Anyone else notice that the CEO of SDS participated in this thread? I did. I appreciate hearing from the MFG of products I'm considering.

Anyone notice the conspicuous absence of representation from Pmag?

Nope, nada, nothing. Just saying.

We have a some people flying with one Pmag and one CPI if I recall. I see no issues with that. If the Pmag went down I don't see any reason it would affect the CPI or vice versa.

CEO? We're a small company, I double as the floor sweeper...

[gasman]

Originally Posted by rv6ejguy

We have a some people flying with one Pmag and one CPI if I recall. I see no issues with that. If the Pmag went down I don't see any reason it would affect the CPI or vice versa.

CEO? We're a small company, I double as the floor sweeper...

Ross, you sure know how to jump in and take all the credit......

[SHIPCHIEF]

Ross;
In Post #115, you referred to single point reliability. Those failures come in 2 kinds: Instant total failure, and progressive failure.
Although modern electronics have a reputation for reliability, they are also perceived to fail utterly and instantly.
A Kettering (points) ignition is less reliable, but has a reputation for slowly failing, giving fair warning so it can be repaired before dire consequences.
I don't need to heap additional cliche stories, and I have a personal experience where my 1988 Harley electronic ignition module failed softly, I changed it before being stranded.
I would be comforted to know that an electronic flight control would have a progressive failure mode.

[skylor]

Originally Posted by Chkaharyer99

Anyone out there running one Pmag and one SDS CPI EI?

Are these two devices compatible together on one lycoming engine?

If the Pmag failed or misbehaved in flight as described in some posts would it/could it adversely effect the operation of the SDS CPI EI?

Anyone else notice that the CEO of SDS participated in this thread? I did. I appreciate hearing from the MFG of products I'm considering.

Anyone notice the conspicuous absence of representation from Pmag?

Nope, nada, nothing. Just saying.

Charlie,

Did you get the chance to meet the aforementioned CEO at Reno?

Skylor

[rv6ejguy]

Originally Posted by SHIPCHIEF

Ross;
In Post #115, you referred to single point reliability. Those failures come in 2 kinds: Instant total failure, and progressive failure.
Although modern electronics have a reputation for reliability, they are also perceived to fail utterly and instantly.
A Kettering (points) ignition is less reliable, but has a reputation for slowly failing, giving fair warning so it can be repaired before dire consequences.
I don't need to heap additional cliche stories, and I have a personal experience where my 1988 Harley electronic ignition module failed softly, I changed it before being stranded.
I would be comforted to know that an electronic flight control would have a progressive failure mode.

I think it's best not to group our electronics in with others like those in old Harleys. Our goal is to NEVER have a failure which could stop the engine and we've got over a half million flight hours showing that's possible. Also, remember the bench test ECU with 145,000 hours on it. Nobody here is ever going to fly an RV even 1/10th of that time, even Vlad. The components of today coupled with good design should yield something with a MTBF many times greater than the Lycoming engine they are controlling.

We'll have some new people coming in to the market which have no previous track record in the field trying to convince you their new whiz bang XXX is the best thing since sliced bread. Only time will tell but usually a perfect controller design does not come on the first iteration. We've seen lots of smart people try and fail. Initial lessons are hard won and only with actual experience doing it. Lab testing is important but the real world is the actual proving ground which defines your success and only time will tell if you did well or not.

As a competing manufacturer, we are in a unique position to hear from people using those other products when they fail and come looking for a solution. We hear the good and bad about customer service going along with the failures or problems. We probably never would have developed the CPI if all the other EIs were really good because we'd never get any market share. I could tell you of a conversation with someone using a competing product who had 5 failures in not too many hours and others who've had multiple failures as well. Those people have lost total confidence in those brands obviously.

Some stuff we see on other brands, we shake our heads at after seeing the failures. They were very predictable, at least from our experience.

We've heard of several high end (expensive) ECUs fail almost regularly in the heat and pounding of the BAJA/ SCORE off road races where SDS just keeps running year after year. One of our clients has over a dozen class wins with the same old SDS ECU. Several competitors running the other brands finally switched over to us and have had no more failures. We were very happy to have one of our clients win the SCCA GT3 championship for the 4th time last month. The auto market gives us a chance to test reliability that doesn't present itself in the aviation environment but there have been spinoffs both ways to improve the products overall.

Our reputation for reliability did not come overnight and it did not come without some hard lessons in the earlier days but I'm proud of what our small team has accomplished over 23 years. Hard work but very satisfying. I enjoy going to work every day. We're working to innovate, design new parts to make installation easier on a wider variety of engines, bring customer requested features and ideas into our products and improve them across the board. I've started on a series of videos to help people with installation and use of SDS products-sorry they took so long. I'd like to thank many of our loyal customers who've directly helped us to improve, test and uncover problems during development. We can't think of all these good ideas ourselves!