EricJ

That's easy to believe with the issues they've outlined, particularly the crank. I doubt they'd send you away if it didn't make sense to do so. It's not in their interest to wind up charging people more for an overhaul than better options would cost.

The crankshaft is by far the most expensive, and heaviest, part of the engine. It is definitely a cost driver if it needs to be replaced.

It's unlikely to be ignition related if the cylinders don't fire at all, since the ignition is redundant and it's unlikely that both sides would fail exactly the same. So single-point-failure items like valves or fuel injection seem more likely.

If you just leave it running while the two cylinders miss do they eventually come online? If so, that sounds like sticking valves that just unstick as the engine warms up. That's pretty common.

One way to push back on that is to make it an issue for the customer, e.g., complain to the FBO or the airport manager. If it becomes a hassle for them to deal with mis-billings, then they'll put pressure on the billing company from a customer perspective, which has more weight than us. Complaining to the regulator, the FAA, may have weight as well. The AOPA is already aware, so I don't know how much more that helps or not.

A 275 for just the AI spot is not a bad option. I had replaced a failed DG with a G5, and then replaced the AI with a second G5 later and then deleted the vacuum system. It might be easier and less expensive in the long run than continuing to deal with the 52D177.

Tempest are great. I've been using them exclusively for years. They have the pre-lubed gasket, which is nice, but are generally very good filters.

My JPI900 works fine with the sensor on top of the dual mag at the magnet. There is no connection from my JPI to the p-leads.

Yes, some German fighter aircraft carried MW-50 (50-50 water-methanol) and also nitrous injection at high power demand. Some allied aircraft, e.g., P-51, also used methanol injection at emergency power settings. German avgas was 90/100, US was 100/130 (generally for both for much of the war). There were still a large number of German high-output engines that ran on 90/100 and made a lot of power. I'm not sure what all the tricks were, but they seem to have been effective.

I was just wondering how you've been doing and was hoping for the best. Thanks much for the update, and thanks so much for your posts here and sharing everything that you have. And thanks for being inspiring now with your grace and humor. You and Andrew deserve more time together, but I'm glad for what you've had. Godspeed to you, and best wishes to Andrew in a difficult time. I have more heartfelt feelings but no words. :'(

GAMI's test of the Beech panels as "hard data" refuting multiple (and growing) cases of field failures suggests to me that GAMI either doesn't know how to do testing for field failures, doesn't want to do proper testing, doesn't care, or perhaps even wants to deliberately obfuscate the issues. None of those possibilities inspire confidence in their responses or statements, and, as you mention erodes confidence in whatever testing they may have done previously. I can understand a small company with a large investment in a product being reluctant to do anything that doesn't promote it or put it in a positive light, especially when the process doesn't really allow them to make significant changes without having to start a lot of things over. It does put the burden on the users, though, and I still hope the bad experiences in the field are limited to economic consequences rather than anything actually safety related. Keeping my fingers crossed, but it might take some time for all of the materials issues to fully play out.

On the J model the alt-air inlet is not affected by deleting the ram air. You can see how the air box works in the M20J diagram posted above. The alternate air inlet remains the same.

Sometimes that's an indication of a suboptimal air box design. The M20J got a redesigned airbox and there was so little gain from bypassing the filter that after a few years the factory deleted the ram air. Mooney made a ram-air delete kit for the previous J models and we installed that on my airplane. Flying in rain or any dust is not good without the filter, and can wind up signficantly impairing the fuel servo. I doubt you'd get much gain on a C model by bypassing the filter, especially if the filter is kept clean.

+1 that I think C models never had it. It's a straight shot from the intake filter to the carb, so it probably isn't needed (i.e., you kinda already have ram air, and it's always filtered, which is good).

What is your optimization criterion? Speed? Fuel consumption? Fuel efficiency? Longevity? There are probably different answers for each. If you want a blend of more than one, then the TLAR method (That Looks About Right) is often a reasonable approximation.

I like that Mr Luvara gave more of his credentials this time. Some of us mentioned before that his previous tests looked very nicely done and well-controlled. He's an engineer and a pilot and an A&P and has quite a bit of experience in the field. I don't think there's any reason to think the tests weren't done competently. They look reliable to me (also an EE and pilot and A&P). https://www.linkedin.com/in/mike-luvara-828531/

Not much, imho. Condition is far more important.

The capabilities are comparable but I found the user interface on Avarex to be unusable. Seemed like a step backwards to be more cute and minimalist or something.

The JPI engine monitor uses a sensor on the dual magneto that senses the magnet rotation. It works well with the JPI.

I read the document and it seemed much broader than that to me. Since this is G100UL-related thread, those are the parts that are getting quoted here.

Yes to the above. It is, however, one of the few glimpses that we've gotten into the other side of the story. Only hearing one side for a long time isn't good for informed decision making. As shown above via the link directly to Lycoming's site on the topic, the quotes in the filing track very closely to Lycoming's statements on their website.

My tablets are all Android, and I used Avare for many years until the support started to go from bad to worse, and then they dropped the legacy program for a complete rewrite that seems to be pretty sub-par, imho. A buddy had been using iFly, so I gave that a try and like it a lot, but it has zero support for CAP stuff, which I need. I've kept the legacy Avare loaded on my tablets as backup, so I still use that in a pinch. I'm expecting that I'll switch to the android version of Garmin Pilot in September when my iFly sub expires, so by then I'll have traversed essentially the entire universe of Android EFBs. We'll see how it all goes, but I'm hoping I'll like GP enough to just land there and stay.

Torque and hp are related. For torque in ft-lbs and power in hp, the relationship is hp = (torque * rpm)/5252. This is why dyno plots showing both torque and hp always have the curves cross at 5252 rpm, because they're the same at that rpm. Many engines with well-designed intake and exhaust systems will produce more or less constant torque across their operating range, which means that generally hp increases linearly with rpm. This is why max power happens at or near max rpm, and why many applications get more power by spinning the engine faster. This is also why many aviation engine applications, especially experimentals these days, use gear reduction so that the engine can spin faster than the propeller so that they can produce more power. Diesels naturally make a lot of torque, but often can't spin fast enough to generate a lot of power. In a vehicle this is made useful with gearing. In an aircraft if it spins fast enough to turn a prop, that's already ok. In WWII the main applications for needing high torque at low RPM were aircraft and tanks, so many tanks also used aircraft engines (e.g., the M4A1 Sherman used the same Wright engine as the C-47, the M3A1 Stuart used a 7-cylinder Continental radial, and the M22 Locust used a Lycoming O-435). An IO-360 making 200 hp at 2700 rpm makes (200*5252)/2700 = 389 ft-lbs of torque. If you've ever looked at a typical small aircraft cylinder and piston compared to an automobile engine, it's clear airplane engines are made for low rpm torque, since they can't spin very fast or the propeller loses efficiency.

Also from the same document: "The two largest OEMs of the engines placed in these aircrafts have also refused to approve G100UL. Lycoming Engines, which has been producing piston aviation engines for over 95 years, has expressed a willingness to independently review technical documentation regarding G100UL, but GAMI has refused to share this information unless Lycoming agrees to a “gag-restriction” that would prohibit Lycoming from disclosing any of its findings, including any adverse safety findings to FAA. See Hoyt Decl. Ex. B (Lycoming Service Advisory). As a result, Lycoming cannot undertake the “rigorous evaluation” of G100UL necessary to conclude that it can be safely used in its engines, and Lycoming has not added G100UL to its approved fuel list. Id. Because Lycoming’s warranty coverage excludes damages caused by fuels that are not on this list, any pilot who uses G100UL would void the engine warranty. Id. The other OEM of aircraft engines, Continental Aerospace Technologies, has likewise refused to add G100UL to its approved fuel list or extend its warranty coverage to the use of G100UL. Hoyt Decl. ¶ 17." Another pertinent tidbit from the filing is that the CA legislature didn't view GAMI as qualifying as a "commercially available fuel" since it doesn't conform to an ASTM specification: "The Legislature also addressed “commercial availability,” reasoning that G100UL will not become “commercially available” until it obtains an ASTM Specification: The FAA’s approval of an unleaded avgas for use in these aircraft is an important first step in the process of transitioning to an unleaded fuel for the entire GA fleet, but it is not the only step needed to ensure a safe transition. Fuel distributors and FBOs lack safety assurance without an industry consensus standard or ASTM International product specification. At present, G100UL is not commercially available for distribution and sale in the U.S. largely due to the fact that it does not have an ASTM International product specification."

Fuel flow tells you the max power than can be produced. Since the amount of energy in a gallon of gasoline is known, the flow rate tells you how much power can be produced at that flow rate. If you can somehow compute the efficiency of the burn, that'll tell you how much power is actually being produced. Subtract losses due to friction, pumping, etc., and you know the power produced. You can also work backwards assuming the rated power is correct and use the RPM and MP to scale down from that. So combining the three to make a reasonable estimate of hp, especially from a table of known or expected performance, is a reasonable way to estimate % power. Depending on how sophisticated the algorithm wants to get, it could also use OAT to improve it a little bit. My JPI knows OAT, but I don't know whether it uses it for the % power estimate or not. Cars use Mass Air Flow sensors with intake air temperature sensors and ambient pressure sensors to get a good idea of how much fuel can be added to get an efficient burn, and then look at the amount of O2 in the exhaust for feedback of how close it is to stoichiometric efficiency (or just how lean or rich it is). Our engine monitors don't have access to those kinds of metrics, so they make do with available inputs like MP, RPM, fuel flow, etc. Kinda crude in comparison, but I don't think it's intended to be or needed to be an accurate estimate.