I think these discussions are healthy and welcoming. I read them and go "hmmm" then I make my own decisions. I have been flying since 1966 when I took my first ride as a civil air patrol cadet in High School in a PA-22 108HP. As a student at Embry-Riddle, I was an understudy of Dr. Richie (RIP) a true pioneer in failure analysis (FMEA) of everything aviation-related. I understand failure modes, and most importantly how to mitigate the risk for each independent system or collectively (through risk priority number= severity x occurrence x detection...) I am also very familiar with E-Mags and other electronic ignitions which is why after careful consideration I chose a dual SDS ignition system. It wasn't by "gosh or by golly" that I arrived at my conclusion. Considering that my initial choice of ignition system was a Dual Bendix D3000 mag with a single failure mode (the main coupling), I asked what else is out there... and here is what I considered 1. A dual mag setup such as the aforementioned dual mag - Four points, four capacitors, one coupling = Total 5 points of failure minimum2. An independent mag with an electronic ignition driven by the timing gears - Minimum of four points of failure (points, capacitor, two couplings)3. An "E-Mag like" with an electronic ignition driven by the timing gears - Engine couplings = two points of failure (minimum) 4. Two independent electronic ignitions with no mechanical moving parts - dual independent battery backups - Component failure 5. Just screw it and go sailing... My most predictable component failure is the spark plugs. So moving forward I then wrote a proactive maintenance schedule in my POH and annotated it in my conditional inspection form to reduce the risk of component failure. Additionally, during my selection process, I prioritized the failure modes of each system, mechanical and electronic... from highest RPN to lowest RPN noting that it’s worth emphasizing that it’s nearly impossible to address every potential failure. Instead, I focused on addressing the potential failures that would most jeopardize the safe outcome of my flights and I chose from analysis and not from bells and whistles... just my rambling thoughts here trying to justify that $50K I spent on getting educated at Embry-Riddle back in the day... keep building Luis R Claudio, KR2S N8981S On Friday, July 8, 2022 at 06:23:13 AM CDT, victor taylor via KRnet <krnet@list.krnet.org> wrote: To answer Chris yes I do have a flying KR2 with a single electronic ignition though I was actually talking to Dan Diehl yesterday about adding a magneto for a backup. I do contract work for Velocity Aircraft as a pilot. We love electronic ignitions and put them on every airplane. They are the way to go and in the past have gone 100% electronic ignition but over time have had enough failures that we went back to having one mag. I also test fly new airplanes for M-Square who builds the Zenith CH-750 SLSA. I actually have had two electronic ignition failures with brand new aircraft there in the last couple of years. M-Square is still committed to 100% electronic at this point. Just to be clear I’m not knocking electronic ignitions nor their reliability. If you have dual electronic ignitions though you likely are relying on the same electrical system to run both systems. Up until four months ago I had never had a magneto failure in my 40 years of flying but recently I lost a magneto while ferrying a Grumman AA1A. Fortunately the other one got me to the nearest airport where a safe landing was made. There is a reason why aircraft manufacturers such as Velocity have reversed their positions on going 100% electronic. And that reason is failures in the past and accidents such as the one in Kissimmee. When Teladyne Continental first built their full FADEC engine system it kept experiencing total ignition failures in flight. After over a year of flight testing with multiple in flight failures yet not a single one in the test cell they finally got to the bottom of it. The problems was found to be the frequency that the US government uses to communicate with submarines was interfering with the FADAC system. The fix was simple by shielding the system. One of the functions of this group is to make the KR’s safer. That’s done by discussions and experience. Mostly bad experiences and I’ve personally had those bad experiences as a professional test pilot. All of us in this group look at canopy latches a little closer today than we did a year ago. Controls have gotten balanced, fifth bearings have been added to engines, fuel tanks are being moved to the wings etc. You would think that over the years we’ve fixed every possible failure point. Have we? It’s our duty in this group to be devils advocate at times and to point out past failures of similar systems.
Victor > On Jul 8, 2022, at 00:24, John Gotschall via KRnet <krnet@list.krnet.org> > wrote: > > > Hi all, > > Quite a bit of commentary about risk, system failure etc. > > So I am convinced everything will fail sooner than later. I make my living > on failing machines, so I may appear a pessimist about machines, or an > optimist about future employment fixing them. On the upside there is so much > failed stuff I get paid more than just several times every day since 1988 to > set those broken machines straight. > > I find it particularly interesting to see the failures that come in groups or > waves. I experienced such an odd failure scenerio in aviation recently. > > I bought an experimental flying boat, a volmer home built, OMG, what a pretty > unit! And a blast to fly! A cub can't touch a volmer for fun. Sadly I > broke that and am still working to fix it. > > Anyway there is an annual seaplane fly in at NW Idaho, and I and a friend > went in the volmer. What a blast! the mountain crossing, middle of nowhere > overnight camping, etc. However the alternator quit near Idaho and we made > our way there and home by never turning on the battery switch the whole time, > except to run the starter motor, and then to cross under the Seattle class B. > Needed adsb working for that. > > I found the High current alternator output wire had failed by vibration > fatigue and had simply broken off that big alternator output post. Simple to > fix, and I replaced the entire wire with welding cable, better for > vibration. No big deal. > > Then I broke the Volmer (another story), and needed another flying boat so > bought a lake LA-4. We found it in Arkansas and flew it home to the Seattle > area. > > The same seaplane fly in came up in Idaho this year, and we went again this > time in the lake. A complete blast for all the same reasons, but on the way > home the alternator quit outputting current! This time the plane has heavy > electrical laods that quickly consumed and flattened the battery in short > order (less than 40 minutes) on the final leg home. instead of panic we just > turned west to get out from under the class B, shut all the electrical off > and used the hand hydraulic backup pump to operate the gear and flaps. Made > the uneventful landing at home in the backyard and went digging for the fault. > > Dang if it wasn't the SAME DAMN WIRE that broke in the Volmer! On the second > occurrence of the same trip. Except this time the wire pulled out of a bad > crimp rather than broke off. Pulled out of a bad crimp on a certified > factory built plane. hmmm. > > Well, both the Volmer and the Lake are dual mag lycomings. An o290 and o360. > > So I will say mags are a great choice, from experience. In both cases mags > brought us all the way home. My kr has one mag and one electric ignition. > It'll probably make it home without an electrical system. > > cheers! > > > jg > > > > -- > KRnet mailing list > KRnet@list.krnet.org > https://list.krnet.org/mailman/listinfo/krnet -- KRnet mailing list KRnet@list.krnet.org https://list.krnet.org/mailman/listinfo/krnet
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