Ryan ORL

This sure is a cynical group. Personally, I would rather have expensive-but-available Mooney parts than cheap-but-unavailable parts. I only rarely need actual Mooney parts but when I do need them, it's usually something standing between me and actually using my airplane.

Of course, not giving the mag remnants to anyone until we settle on whats going on. It's also not out of the question the FAA will want to see them.

Small update... Western Skyways has my engine and has started disassembly. Hopefully more news there soon. I met in person here in Orlando w/ the rep from Champion so he could inspect the impulse coupling debris in person and photograph it. He was obviously pretty circumspect in his commentary but did say that while they have seen impulse failures of this type, he has never seen them with this low time and insinuated that they don't trust QAA/Hartzell's claim that these were new couplings. They want me to send them the parts for analysis in their lab. Getting another look at the coupling myself, it is clear as day that the rivet holes are very worn out, they're oversized and elongated enough to be obvious to the naked eye. I think even if I were to accept that these were "used" couplings, the chances of the identical failure in <100 hours is simply too improbably to consider. Probably even an unmaintained and uninspected coupling should be expected to carry on well beyond 500 hours before this sort of failure would occur. I also separately received a call from Certified Engines, my original engine shop, saying that they finally settled up with QAA/Hartzell on the previous mag explosion (QAA paid them) and they told me they were informed by QAA that they would be paying for this one as well. I don't have that in writing from them yet though. I haven't sent the mag parts to anyone yet because I want QAA/Hartzell to give me their view on what they want to occur now. The most direct warranty claim is through them, however I certainly understand their point of view that this is not 'their' failure (if these were indeed new couplings), which is obviously why they wanted me to involve Champion. From my point of view, the cleanest solution is that QAA/Hartzell agrees to cover the teardown expenses, takes possession of this mag (and the previous which they now paid for), and pursues one consolidated claim against Champion. Then they can decide under what circumstances they release these parts to Champion, and I am no longer in the middle. Still no firm agreement from the parties though... and I do periodically see email traffic back and forth, so I know they are communicating behind the scenes now.

Just extrapolating from what I know of modern car engine design, I suspect more modern cylinder head (combustion chamber) design could buy a bit of extra detonation resistance versus our older designs. The obvious improvement though would be a full modern EFI system. Without the stupid fixed spark timing and uneven fuel delivery, you could effectively eliminate “the red box” entirely. Easy enough to electronically pull timing when cylinder temperatures get high, or when lugging the engine at lower RPMs. For getting a lot out of lower octane fuel, though, I think the really difficult thing is the air cooling requirement and the vast operating temperature range that implies. Water cooling an engine really helps avoid hot spots and even the design of that matters a lot… Chevy squeezed a bit more out of the SBC (and was able to up the compression ratio) when they went to reverse cooling (heads first), although they later abandoned that for other reasons.

It was at WestJet RAP in the MX hangar there, but I suppose it's possible they've moved it while they wait. I'm unfortunately back in Orlando so can't keep an eye on it directly.

I got the impression it was the latter.

The Mooney certificate. There was some discussion of how to specifically structure the deal so as not to invalidate the certificate. I didn't understand (and so don't remember) the specifics of how that works, but they were pretty clear that being able to do stuff under that certificate was the whole goal.

They had some delays sending me the empty crate so they haven't gotten it yet... hopefully next week!

Yeah, my interim plan of having a "brand new Champion Slick mag" to avoid the QAA issues is not such a slam dunk at this point. Doing SureFly as soon as possible.

My recollection of what the LASAR rep said at Mooney Summit last weekend suggested that they would at least be heavily involved in replacement parts manufacturing in Kerrville. His specific example was the nose gear trusses... right now apparently the tubular segments are hand-cut and ground to the proper length. He said they were working on setting that up to be laser cut so they could produce "1000" in the same time as one currently takes. So that sounds to me like they think they'll be producing parts at the Mooney factory and presumably under the Mooney certificate. He mentioned that they were very careful to structure the deal to be able to be under their certificate somehow.

Some interesting updates to share, and the mystery deepens... I received a call from the Director of Product Support at Hartzell, which apparently owns QAA. He was aware of my prior case and had inspected that magneto at my old engine shop. He just learned about this latest case from my emails to my old engine shop, which they forwarded to him. He informed me that it is their opinion that there is nothing wrong with my engine or anything else related to my operation or the installation. He said QAA overhauled magnetos do not have 'overhauled' impulse couplings, but rather they always replace the impulse coupling with brand new OEM Champion impulse couplings. He encouraged me strongly to file a SDR with the FAA and to attempt to open a case w/ Champion directly, and that they would help any way they could from their end. He also suggested they were aware of a few similar cases, but this is the only known case of two failures consecutively. I got in contact w/ Champion's Quality department and promptly received a call from their Director of Engineering for the Piston stuff. He didn't really give me any new information but said he wanted to inspect the magneto in person while he is in Orlando next week. (I am having the magneto parts shipped to me) QAA apparently will also be sending a representative to be present. I also filed the SDR w/ the FAA... we'll see if there's any followup there. I think the Hartzell guy was going to make some FAA contacts aware of it. So obviously if it is in fact the case that these were brand new Champion couplings, that's pretty concerning.

I think it could be quite a concern with this fuel, however. From what I've read about it thus far, its MON is lower than 100LL and G100UL (neither of which are actually 100 in reality, but higher), which would significantly reduce detonation margins in my engine (IO-360-A3B6) for example. Whereas previously detonation might only occur >25" MAP and at certain temperatures, it is very easy to imagine it occurring at previously-conservative values.

Thanks guys! That seems to be the most straightforward solution then... switch to the hall effect sensor for the G3X and ditch the P-lead pickups entirely (except for the R1). I think with that setup, there's no need for the Tach2.

Hey everyone! I have a G3X Touch + 4 cylinder EIS in my J. Before I had my panel installed, when I bought my airplane, it had a EI R1 Electric Tach in place of the factory tach. I also had an old Insight G4. When we installed the G3X, I elected to retain the old EI R1 tach as a backup, since in case of G3X PFD failure, I have no other source of tach info. This setup seems to work fine. I also happen to know, because of some other recent avionics debugging, that my G3X is configured to use P-lead inputs for tach sensing. (In this case, my G3X RPM would read zero on the left mag only, and the problem was a bad connection at the resistor which is right at the P-lead) Because of my recent (very costly) magneto/impulse coupling issues, I plan on switching my left (impulse) magneto to a SureFly EIS. I would like to keep the same setup, however, with the G3X and the EI R1 continuing to work as before. I've been doing some research on whether I can keep this setup and it seems that I should be able to (there a small capacitor needed for the R1 apparently)... but I am trying to figure out whether I will need the Tach2 box or not. Based on the G3X Installation Manual, I believe it should be possible to have a magnetic pickup installed in only one magneto and that should not require any P-lead sensing. I am not sure why mine wasn't setup this way. In this case, I think I could just have this setup in the right (conventional) magneto, and I would not need any Tach2 box from SureFly. Does anyone know if the G3X + EIS STC requires the dual P-lead setup, or did my avionics shop just choose that for convenience? Only requiring a single tach input that is not dependent on the P-leads being ungrounded seems simpler to me.

I have the Slick start unit also, and a Skytec starter… not sure whether it turns over that fast, never considered it. Anyway, the Slick start is great for hot starts… I do wonder if it’s somehow involved, in that you can get the engine to start catching when ordinarily it wouldn’t (and therefore you can have the impulse engaged, then unengaged, then engaged again in succession if it’s a bit unstable before it finally gets going fully)

Well fortunately a few engine shops responded quickly and the prices weren’t as bad as feared. Western Skyways is going to handle the IRAN this time.

As for the color of the cracked material, I believe it probably wasn’t cracked at all until it finally destroyed itself in one violent event. The persistent failing I believe was the pawl rivets wearing and elongating their hole. And probably the pawls themselves were wearing some on the “heel” end. Some of that’s visible in the photos. Once it finally caught at running engine speed, kaboom.

Unfortunately I didn’t get a photo of that side, but it visually looked mostly ok. Engine is definitely going for IRAN at this point so maybe we will find something more…

This is the best explanation of my failure mode I have seen https://youtu.be/Pw0FOB54tV0?si=b45tvQVACVpwxqqf (b) Pawl rivet wear. The 500hr inspection involves checking the pawl rivets for wear. Excessive wear allows the heel end of the pawl to start contacting the stop pin which will eventually cause the latching end to be thrown out. Centrifugal force at normal engine speeds keeps the latching end clear of the stop pin but when this fault occurs the sudden engagement with the stop pin will destroy the coupling which may then shed broken metal into the engine accessory case. This will likely result in both magnetos being put out of action plus further damage to the engine. Such an occurrence in a single engine aircraft will leave you looking for a suitable field in a hurry.

The impulse coupling locked up at speed and tore itself apart. How this occurred exactly is still a bit of a mystery, but a cursory examination of the internals revealed that both rivets on the pawls (the hinge points I guess?) were sheared off, with one of the holes being elongated. From my reading, loosening or failure of these rivets can allow the pawls to shift outwards slightly and grab onto the catch pin when they should be held in by centripetal force. This occurring at normal engine speed results in the damage you see here. The scary thing here is, given this happened well under the 500 hour inspection interval, it is not something that can be inspected reasonably at annual or any other way without disassembly. And this can in theory fail in flight.

Savvy seems to agree in this case. There's a lot of large metal fragments missing into the engine. They were onboard with a simple repair if the pieces could be accounted for, but unfortunately not. In fact, when the magneto was removed, there was a mass of metal dust/sludge that can only be described as the consistency of toothpaste. Plus presumably lots more that went down into the accessory case. And the gears on the engine side did sustain some minor damage. In principle it needs just a look through of the accessory case and the sump flushed out, but I don't think anybody is signing their name to such a thing under the circumstances.

It's at the mx shop attached to WestJet Air Center. They are reluctant to do anything with it without an engine shop looking at it for liability reasons and honestly I don't blame them. I think the engine would have to come off anyway to open the accessory case on my J. The right mag is indeed no impulse and was already replaced with a brand new Champion Slick, and is no longer a QAA mag. Unfortunately the left mag was a QAA Slick, and the only reason I had left it that way was because, at the time (no longer), the engine was under warranty. I definitely will be going SureFly. In the meantime, I think we will be doing a brand new Champion Slick on there. I need to discuss w/ the engine shops whether they can do it with the SureFly from the start. Never had any kickback during start.

Unfortunately a rather large part of the impulse coupling itself is lost into the accessory case (and is presumably in the sump)

Pretty good view of the damage here, definitely needs replacement. Nothing much was visible on the engine side gear, just some small chipping. The biggest issue is the missing ear of the impulse coupling, which is a big chunk!

Here is an opinion from Aircraft Magneto Service, who were kind enough to offer an opinion: Impulse cams failures happen, but I would call it exceptionally rare. QAA are now exclusively using Hartzell components, they have issued at least one service bulletin (SB 225) in which they had an issue with the snap rings coming loose. I have not seen many Hartzell mags 2024 or newer, its not out of the question that they have a manufacturing defect on newer impulse cams. Engine vibrations do reek havoc on impulse cams, If you haven't I would ensure the prop is balanced and no unusual vibrations are occurring. When installing the drive gear on the magneto, the drive gear should have some "slop" to it, end play up and down. I have experienced issues on Hartzell cams before where the gear was too tight and have to polish the black oxide off the portion that fits up through the gear. Also its prudent to apply grease inside the gear to prevent binding. Snap the magneto over in your hand after the gear has been installed and ensure its "smooth", no binding. Steve Cotton AMS