EricJ

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.

Appendix D is the minimum regulatory requirement. There is also a regulation that an inspector must use a checklist, and Appendix D is the minimum checklist. Other checklists can be used, like the factory checklist, but they must contain all of the items in Appendix D. I came to the same conclusion, especially after repeatedly repacking bearings that were still full of good grease. There's a tradeoff between doing useful maintenance and increasing the risk of maintenance-induced failures, and doing stuff too often is not productive and adds risk. Agreed. The Lycoming service document on cleaning injectors warns that excessive cleaning of the injectors is detrimental.