EricJ

Well now it's definitely gonna leak.

Yes.

Yes, the AD is not applicable to your airplane. I have the same actuator and am also not subject to the AD. It's still a good idea to properly grease/service the actuator at annual and you can assess lash by hand-turning the coupler and see how much free play there is.

Mine was $280 last July.

Oh, I missed these when you first posted them. How much are you thinking for the eyeball fixtures?

The overseas aero club that I worked at as a teenager ran 115/145 fuel that we got from the Army. An AF Flying Club not too far away also ran 115/145, but kept getting cracked cylinders and was blaming the fuel for some reason (scapegoat du jour, easy substitute for shock cooling). We never got cracked cylinders, we ran the same fuel, and iirc our airplanes flew a lot more than they did. It was a always a bit of a mystery why their cylinders were cracking, but I think they were the only one of the US flying clubs in Europe that were running 115/145 that were having the problem, so I just figured it must be something they're doing. Years later I learned that a common reason for cylinders cracking between the plug hole and exhaust port is over-torquing spark plugs on installation. I think they just had an over-zealous mechanic that maybe didn't own a torque wrench or something. There were also some local US jump clubs with 182s and Reims Rockets (180hp 172), and they'd climb at full power, throw everybody out, chop the power and descend as quick as they could to pick up the next batch, whereupon they'd climb at full power, descend quickly with the throttle chopped, etc., all day long. They did not have a big problem with cracked cylinders, either. It's still pretty common for recip jump airplanes to climb at full throttle, throw everyboy out, and descend fast enough to beat the jumpers to the ground, and repeat the cycle all day long. There are so many counter examples for why shock cooling isn't really a thing that I'm always a bit puzzled at the people who insist on thinking so.

Likewise twins used for training routinely shut engines down at cruise. Sometimes there are multiple start/stop cycles per flight. They don't seem to suffer any extreme ill effect for it.

There may be a voltage difference shown on the G3X between the batterie(s) and the GPU. e.g., the batteries may show 26V and the GPU may show 28V or something. You can try yours and see the difference. Don't switch while it's live, boot everything separately and see if there's a difference. If your GPU is decent and puts out 28V (or at least significantly better than the batteries), it may may be easy to tell that way.

Pin 15 is DC Ground = Common.

+1 on this. We're probably thinking of the same guy. I couldn't come up with anybody else off the top of my head. There are a lot of Mooneys at DVT, but I can't think of any M20C-specific instructors there. I'm probably missing somebody.

Some people won't like the idea, but the Delphi Weather Pack connectors are very good and designed for wide temperature ranges, vibration, and keeping weather/water out. If you just need one or two you can sometimes get them off the connector rotary rack at an automotive store, or Mouser, or Amazon or a bunch of places. They're pretty popular. They're pretty much my go-to when I need a reliable connector with good environmental qualities.

Do you have an engine monitor? What is the oil pressure doing during these events? Any new oil leaks?

The valvewizard is not a bad choice for an angle-valve engine. For parallel valves there are some easier tools, and some DIY methods that also work well. I have a valvewizard for the angle-valves and one of these for parallel valves: https://www.aircraftspruce.com/catalog/topages/compressor.php Edit, there's also this, for Lycoming engines: https://www.aircraftspruce.com/catalog/topages/compressor2.php

And don't forget the M301, which wound up being very successful...with a different company after Mooney spent the money on development. I think in recent times the M10 sucked up a lot of money for zero benefit. Decent concept, just horrible execution.

The idea is to get the signals to or from the circuit boards in the radio as cleanly as possible, and pin 15 is the closest connection to the grounds on the circuit board(s). That's where the received signals enter the receiver, and where the outgoing signals are generated. There are compromises that can be made, but generally that's the idea.

Did you try both intake and exhaust? It can be either one.

Pins 15 and 5 are the current returns for the radio unit. They go wherever they need to go to serve that task. There is an indicator to see Note 5, which may have some clarification on details. There are some decent YT videos out there that show how to use solder sleeves as as easy way to terminate shields at a connector. You can even buy solder sleeves with a wire already attached, and this makes it easier. It's about the only place I recommend using solder sleeves on an airplane, or solder in general. That makes connecting the shields to the recommended ground fairly easy, but the shields should terminate at the radio connector to provide maximum protection for the signals they're shielding. With shielded connectors this is sometimes easier, but in any case, ground the shields as close to the connector as possible. I mentioned earlier that in aviation shields tend to get grounded on both ends, although this is not always optimal from a signal protection point of view. Nevertheless, for mechanical redundancy or whatever reasons, many aviation shields get grounded on both ends. It's not difficult to do, it's just a little more work. Shields always need to be grounded as close to the connection of the signal they're protecting as possible to help prevent coupling any external energy into the signal being protected. That's the purpose of the shield in the first place, so the diagram makes perfect sense from that perspective. Edit: How to terminate a shield with solder sleeve. How to daisy chain shield for multiple wires:

You want the shields grounded as close to their termination as possible, so the connector is the ideal place to do that, and pin 15 provides that. You also want the shield grounds to be the same as the radio ground since their purpose is to reduce the amount of radiated rf or other electrical noise that gets into the shielded signals. Using a ground further separated from the radio may reduce the effectiveness of the shields.

It works well as an oil additive in some cases, and some have found benefit as a fuel additive. It's been used in aviation since before WWII and was shipped in 50 gal drums for use in the big radials in WWII. MMO has a long history of beneficial use in aviation, but it's certainly not a cure-all and needs to be used carefully IMHO. It does seem to be heavier than fuel, and if you add even a little bit at the top of a tank of 100LL and then take a sample from the sump, it'll be clear or discolored and smell funny almost immediately. Some people think it makes the fuel at the sump smell like paint thinner. Since many tanks have been patched over the decades with unknown methodologies, it is not unheard of that a non-leaking tank may start to leak a bit after the addition of MMO. In the case I was involved with a previously non-leaking tank started leaking (weaping a little in two spots) and stopped leaking after the MMO was run out of the tank, so perhaps the sealant hardened back up a bit. I know of another case with a PA-28 tank that leaked after the owner started using MMO. The history of that tank is unknown as well, but it can happen. On the other hand, many people use MMO in their fuel regularly and don't experience leaks. I suspect tanks that have been patched with non-standard or non-approved sealants may be the most susceptible, but that's a guess on my part. The tank that sprung two leaks and then fixed itself looked like a calico cat inside, so it appears to have been patched over the years with a number of different sealants. In any case, I suggest using MMO in fuel tanks cautiously, at least initially to see whether it causes any problems.

My engine has done the occassional morning sickness for years. An acquaintance that has been in the aviation lubrication business for a long time suggested that going back to W100Plus would likely help eliminate the problem. I'd switched from W100Plus to W100 a while back for reasons that I don't recall (something about undesirable side effects of the additive), so it may be worth trying.

I wouldn't recommend putting MMO in the fuel tank, although some do that. It may increase the likelihood of a tank leak. It's more often an oil additive, especially just before an oil change.

Ground is ground, and there should only be very small, stray currents going through the shields, so the wire doesn't need to be large. Any current in the shields should be going to the ground rather than through the pin into the connector, too. The 18awg wire indicated from pin 15 to ground is mostly to carry the return current out of the nav/com, particularly during transmit. The note referenced on the drawing may have some additional suggestions.

That line is indicating that all of those shields are grounded at Pin 15. Electrically just grounding one end of a shield (usually at the receiver if it is unidirectional) is better, but in aviation it is common to see shields grounded on both ends. I think this is just for mechanical redundancy in case one end becomes disconnected, but who knows.

No, it doesn't mean that. Airframe approval is separate from engine approval. This is why the limitations in the aircraft POH and specs in the aircraft TCDS drive rather than what's in the engine TCDS.

They do, but just like in cars they can get unregistered and spin. Letting pressure off the bearings during cylinder removal seems to increase the likelihood of this, so it is recognized procedure to not let the case relax too much. Cars also have the benefit of main bearing caps and much more rigid blocks than we have. We have two essentially relatively floppy aluminum case halves to keep the bearings in place.