Ryan ORL

I have both but I keep my G3X default (and on my iPad in ForeFlight) to showing SXM always. I almost never look at the ADS-B WX in my own airplane. (But I use it often in aircraft that I instruct in) SXM weather is just better. More detail, further out, faster refresh, etc. Now, maybe that isn't worth it for the type of flying you do, but it depends. But, as a Central Florida pilot who is always contending with thunderstorms, one feature of SXM that I find absolutely crucial is the ability to look at both Composite and Base Reflectivity. ADS-B does not offer Base Reflectivity, but that is the picture that shows you better where the really nasty stuff is. I don't particularly care about precip falling up in the flight levels. Particularly after the thunderstorms have begun to dissipate, the Base vs. Composite picture can tell two very different stories. I also appreciate that SXM has the storm cell attributes, etc. It has a few nice little features like that.

Mike and GeeBee, that theory sounds very plausible to me! Will definitely report back what happens w/ the new condenser. I suspect you're right.

Going to try that and see what happens, thanks everyone!

I don't know the exact mechanism but the logic goes something like this... (Mike Busch described this calculation in general terms on a podcast once, but it basically just follows logically): First, the engine monitor has to decide whether the engine is ROP or LOP. This can probably be pretty easily approximated just from looking at whether the fuel flow is in the plausible range (given those tables) for "best power mixture". Anything less than a particular fuel flow for a given MP/RPM combo can be assumed to be LOP. If ROP - Excess fuel, air (MP) is the limiting factor. % power is given by MP/RPM table lookup. Fuel flow has little measurable impact on horsepower, probably mostly disregarded. If LOP - Excess air, fuel flow is the limiting factor. % power is computed by fuel flow and RPM only, probably using some figures from the BSFC curve.

So this is a bit of a strange problem. Starting a few months ago, I started noticing significantly diminished comms reception, and a loud rapid clicking on the comms. Some brief debugging revealed that it wasn't really comms reception at all, but rather the loud clicking noise was playing hell with the GTN auto-squelch and the problem seemed to be slowly getting worse. Some further troubleshooting revealed that the problem was only evident on the RIGHT magneto, i.e. the clicking noise disappeared entirely when running only on the LEFT magneto, and the clicking was certainly RPM dependent. It was easy enough to break squelch on COM1 and just listen to the click disappear and reappear when switching the mags. My local shop started debugging this, first checking for loose grounds (etc) and checking the magneto harness for pinching, chafing, or arcing. They found one slightly loose shield and corrected that. They did some kind of high voltage test on the harness (~110 hours old, new at my recent engine overhaul) and found no problems. There was also nothing visually obviously wrong with the harness or leads. So I did a bit of further debugging with a portable radio. The clicking was actually audible on the portable comm radio with all my aircraft electrical systems entirely turned off, in other words it was most definitely arcing somewhere, and our assumption was it was inside the magneto. Sure enough, the shop tested the condenser and found it was a bit out of spec, and they put in a known-good spare that they had while we ordered a new one and waited for delivery. That cured the clicking entirely. Comms totally quiet on either mag. Hooray! As an engineer myself I also wanted to understand what went wrong... so fortunately this also entirely made sense... a bad condenser would lead to the points arcing, case closed, I thought. The new condenser is due to arrive this week, so I am still flying on the 'spare' one. I had around 5-6 trouble-free flying hours on it. But on Saturday when I went to fly the airplane... the clicking was back! Now, we haven't had a chance to dig into this yet... we're of course going to install the new condenser, but my concern is that either I am just enormously unlucky, or something else is killing the condenser and the new one will just fail again. So does anyone have any theories on what the hell might be going on inside this magneto? The mag itself is relatively recent... 110 hours also, from the overhaul, it was an overhaul unit from Quality Aircraft Accessories. At this point I suspect there must be some other internal fault there... I am inclined to just send the whole thing out for overhaul or even try to get an exchange unit. I am honestly tired of chasing the issue. Could it also be something with my plugs on that side? I run all Tempest Fine Wires that have maybe a few hundred hours on them.

Certified Engines Unlimited in South Florida. $1500 expedite fee. To be fair they only promise 8 weeks for that but they got it done in 4.

Base IO-360-A3B6 OH cost (March 2024) was $40k plus or minus $1-2k (based on at least 8 shops I got quotes from). That assumes reusing basically everything and OH’d cylinders. Standard turnaround time 14-18 weeks plus or minus. I opted for a new camshaft and new (PMA) cylinders, plus freight and a couple minor extras. $48k for the engine shop altogether. Paid to expedite and got it in 4 weeks. I spent $14k on the rest… removing and reinstalling the engine, new everything (mounts, hoses, etc), overhauling my governor, etc etc etc.

What even is the point of the debate on who is enforcing the STC? It's obvious that it's nobody... Who is enforcing that you aren't doing all your own maintenance without an A&P? Who is enforcing that you don't install unapproved minor mods? Who is enforcing that you are actually current? Who is even enforcing that you have a pilot certificate? In 20 years of flying I have never been ramp checked by an FAA inspector. The only person who has even looked at my pilot certificate is US Customs when coming back from Canada/Bahamas. So if I was only flying domestically I likely would still not be asked. Obviously the vast majority of aviation is on the honor system. STCs, maintenance paperwork, currency records, etc.

Because you were quite transparently implying that I am some kind of shill for GAMI or G100UL. Even now-- "the script", as if I am not capable of independent thought.

I have never met or communicated with George in any way and frankly the implication is insulting. Why can't other companies make a good blend? You would need to ask them. The fact, however, is that these other companies aren't holding these things under wraps... there have been public statements on their composition and the likely limitations. These are well along the path towards certification. Whether or not it may be possible to create a 100UL blend that has no drawbacks and the exact same (or better) performance characteristics as 100LL, the fact is that nobody has done so and there is nothing like this currently in the pipeline anywhere in the world.

There are only a handful of companies working on 100UL fuels and, as far as we can tell from their public statements, the formulations they are targeting involve significant compromises on detonation margins such that modifications to engines and in-flight procedures will be required. Maybe someone comes out of left field with a new as-yet-unannounced candidate fuel (probably unlikely because these take a long time to develop), but for now the situation, based on public statements and evidence, seems to be: G100UL - Potential (or actual) materials compatibility issues with sealants and o-rings, but superior-to-100LL detonation margins Swift 100R and Lyondell/VP UL100E - Maybe (??) better materials compatibility (but with potentially ethanol-related complications) but significantly-inferior-to-100LL detonation margins I think George's point, which is fair, is that if we're talking about unleaded 100LL replacement fuels, your choice is those two buckets. There aren't any magic miracle fuels coming. So which basket of complications would you rather have? Personally, I can't buy any of these fuels in my area and I'd rather not be an early adopter anyway. But if 100LL does eventually get banned (which many feel is inevitable), I know which set of complications I would rather deal with, and it is not remotely a tough call.

It is not just about glide ratio, it is also about glide speed, which in our airplanes is quite a bit higher than a Skyhawk, Cub, etc. A very high glide speed makes your turning circle much larger, increasing the difficulty of the maneuver.

Per the Instrument ACS, DPEs are supposed to be testing on autopilot usage for aircraft that have one installed. "To assist in management of the aircraft during the practical test, the applicant is expected to demonstrate automation management skills by utilizing installed equipment such as autopilot, avionics and systems displays, and/or a flight management system (FMS). The evaluator is expected to test the applicant’s knowledge of the systems that are installed and operative during both the oral and flight portions of the practical test. If the applicant has trained using a class portable EFB to display charts and data, and wishes to use the EFB during the practical test, the applicant is expected to demonstrate appropriate knowledge, risk management, and skill." If you have an autopilot installed, you should expect a DPE on an instrument checkride to require you to demonstrate its use on at least one approach and if you struggle with it or display a lack of understanding on it, that is valid grounds for a bust. (Notice of Disapproval)

It would be (and is) just like the Bonanza. There are practically no scenarios where a turnback is workable in a Mooney, unless you happen to already be on a crosswind before the failure occurs, and there is an intersecting runway available. (Or similar) The issue is the very high best glide speed. Mooneys do have a good glide ratio, but do so at a relatively high speed, which causes the turning circle to be quite large. Conversely, I still conduct flight training in 172s semi-regularly, and I demonstrate what does and doesn't work for turnbacks in that airplane. With a 65kt (and practically even lower at typical weights) glide speed, turning back from 600 AGL is fairly easy, and often even results in being high.

In the referenced FAA Approved Model List (AML), which you did not attach here.

What's the story there? That shouldn't be possible without a badly mis-timed mag, a cracked plug insulator (pre-ignition) or some fuel flow blockage?

I would say 25 BTDC is at least moderately aggressive in the sense that Lycoming saw fit to issue a service instruction telling (asking) owners to re-time and re-mark their engines to 20 BTDC for, among other reasons, high CHTs and better detonation margins. It really isn’t rocket science though… more spark timing obviously reduces detonation margin, and so does lower octane fuel. This is true of basically any spark ignition engine out there, whether it’s in an airplane or not. I screw around with the spark tables on my project Trans Am all the time… but I have knock sensors and an EFI system that’s capable of adding and removing advance as needed. You can push the timing hard right up until you get knock (detonation), and dial it back a bit. If you want more spark advance, the only way would be higher octane fuel… you can just dump cans of toluene in your tank if you’re so inclined. In our primitive fixed advance system the only feedback we have is CHT. 25 degrees isn’t a ton of timing for most situations, but there are certainly going to be *some* manifold pressure/RPM/fuel flow combinations where it’s a bit too aggressive, and the evidence is that the CHTs get a bit high. However even if you’re fine with your temps, the situation is obviously not improved by lowering the octane several full points. It is basically definitional that your detonation margins are worse all around with lower octane fuel. It is also obvious that it is possible to cause mild detonation at high power settings by manipulating the mixture control (I assume we’re all aware of ‘the red box’). It follows then that the red box is larger with lower octane fuel, and importantly, may encompass more operationally useful MP/RPM/FF combinations! Anyway this is all a sidebar… my original point stands. Whatever leaking/sealant problems G100UL has would need to be quite severe to make running much lower octane Mogas in most of our engines the safer option, especially with timing at 25! I would be willing to pay for more than one tank strip/reseal before I just gave up the ability to get book performance numbers without cooking my engine.

There is a whole Savvy webinar about it with data from GAMI, but I am guessing that’s not the kind of citation you’re looking for. The short version is their engines were timed aggressively (25 BTDC), they operated at peak EGT by school SOP, and the observed recession is believed to have been caused by micro-welding due to continuous mild detonation. (Which GAMI replicated in an engine test cell) As to why it’s different than cars in the 70s, one important difference is that many/most aircraft now have hardened valve seats. Especially the Lycoming powered stuff, I guess Continental started doing that much later.

It isn't particularly common with 100LL but if we're talking about a much lower octane fuel (UL94 or Mogas, for example), it obviously becomes a much bigger concern at a much wider range of power settings. That is why the ADI stuff... it would effectively be required for some phases of flight if we were forced to operate on UL94 or something. edit: And I believe the consensus on the UND valve recession issues w/ UL94 come down to it being lower octane.

Assuming a G100UL-compatible sealant exists or could be found, I think I would much rather deal with potential fuel tank leaks from my decades-old tanks but be using a fuel with the proper octane, versus be forced to retrofit some kind of ADI system. Even more stuff to fail, and when it does, it would almost inevitably be discovered at the worst possible time (high power setting on low octane fuel).

Granted I only had an E5, but when I did my G3X panel I sold my old E5 setup to one of the avionics techs at the shop who was putting it in his older plane. Like $1500 or so. That seemed to be ballpark what people were getting on eBay at the time. The EA100 box may have some value if it's working because they fail so frequently. I went through 3 of them on my airplane, and I think they were $2500 to replace! So the guess $5-8 AMUs above for the whole setup sounds about right to me, but really maybe the very low end of that.

Agreed, VNAV is totally just nice-to-have territory for me. I do sometimes use it under IFR though, there's a few places I fly where they like giving descent clearances like "Descend at pilots discretion to 5000, cross 25 miles north of the XYZ VOR at 5000" or some such. Quick work to add an along-track waypoint, type in the altitude constraint, and do the VNAV thing on the GTN. (It's been a little while since I had my 480 but I think it also supported along track waypoints?)

The other thing I will add here, regarding training with a G3X + GNS530W (staged upgrade) versus G3X + GTN650 (full upgrade) is that these are quite different in actual usage and workflow! The G3X is effectively not part of your IFR workflow at all, other than maybe crossfilling flight plans if you don't have a FlightStream. All of your IFR button presses are on the GPS navigator itself, not the G3X, and how you fly these procedures and work with them are identical between a G3X, G5, or GI275-equipped aircraft. It all comes down to the navigator. The GNS530W is a reasonably capable, but very old now, navigator. It has a very old knob-style 'buttonology' logic that involves a lot of knob cranking for some activities. (Seriously get a FlightStream or crossfill via G3X) I find this to be a significant distraction for instrument students. Even people with a lot of experience seem to sometimes grab the wrong knob, and continually mess up the cursor on/off stuff. (Ditto the G1000 aircraft) Importantly, it does not support most leg types you will find in Departure Procedures (most default to just 'VECTORS'), it does not support airways, it can only depict holds as part of procedures, no VNAV, etc. Sidenote: The GNS480 was/is a far better unit and I wish it had gotten the praise and adoption it deserved. It is a better navigator in every conceivable way, both in capability and buttonology, but that is just my .02. I loved my unit. The GTN series navigators are obviously state of the art, and they use Garmin's new touchscreen 'buttonology' logic. It will be a closer match to the G3X, which looks and functions similarly. It supports all the things you need to do under IFR with no compromises. The onboard logic is also superior, especially with respect to vectors-to-final and the pitfalls there. Anyway, the point I am making is that the tasks you're performing in the aircraft under IFR differ significantly between the GNS and the GTN, and the G3X doesn't enter into the equation really at all.

Re: limiting GPS usage, as a CFII, I don't really see it this way. The days of flying IFR /A or especially /U are long gone and arguably tuning/identifying an ILS is much simpler on older avionics. It is much more common to have instrument students that can't figure out how to make the GPS do what they want, or don't properly understand the flight planning logic, or waypoint sequencing, or loading and changing procedures, etc. Especially on an old navigator like the GNS530W, there is actually considerably *more* screwing around in menus and buttonolgy necessary versus the newer stuff. It is true, however, that basic attitude instrument flying is easier on a big glass panel like the G3X versus steam gauges or similar, but that doesn't have much to do with the GPS.

You can do this, the 530W will work fine with the G3X/GFC system, but of course you won't have VNAV which you probably already know. That KX170B is ancient and takes up a ton of panel space. I would see if you can't find something, anything, better than that. Whatever you're putting in the future will be way smaller than that. I assume you also won't be able to have the G3X show the NAV2 CDI from that either, but I admit I am not knowledgeable about the old analog stuff with the G3X. I would vote at minimum you try to pick up a used Garmin SL30 or something. (The only old radio I kept in my upgrade) It's a great unit, small/thin, and can be easily replaced down the line with the GNC215 (was designed to replaced the SL30 in fact, but not pin compatible). The SL30 will at least interface with the G3X in every way except flip/flop of the frequencies. I would also strongly consider the G3X EIS. I am super happy I have EIS on my G3X. It is very nice to have everything on the same PFD, and engine parameter alerts are displayed front and center. Additionally, since you're doing a G3X, that is basically a full panel overhaul, and now is the time to also ditch the analog legacy gauges, which you can do with the G3X EIS. The GTX335 and GMA340 are fine as-is. I am told the yaw damper is also easy to add. I plan to add it to mine later. There is a spot in the servo mounting bracket for it already. (It comes that way) That being said, a G3X + GFC + install including a full new panel is going to be probably 70%+ of the cost of your full system.