EricJ

Mine opened not very far into the takeoff roll and it was a loud BANG and then a LOT of noise. Couldn't miss it. I had plenty of room and just aborted the takeoff, and it had pulled (broken) the stop/prop bar out of the connection to the airframe. Other than that there was no damage and the repair was easy. But, yeah, it was really loud.

Looks like it is available from Newark: https://www.newark.com/honeywell/dt-2r-a7/microswitch-pin-plunger-dpdt-10a/dp/23F4046

It just says to remove the switch, which will prevent the annunciator from illuminating. I think I marked the wire in case I wanted to use the annunciator lamp for something else, but haven't. It still lights up if I push the test switch.

AOPA is the main lobbying organization for GA pilots. Talk to them.

Generally during engine change/overhaul. The accessory case and other components change enough that it is essentially a different engine, and generally not practical to make the change on an installed engine. This has been done often enough, though, that it's worth checking on any candidate J model to see what is installed. All that said, there's nothing wrong with the dual mag installations, either. Some of us prefer them.

The manual for my Hartzell top prop only has one other limitation that might be potentially relevant, that an HC-C2YR-1BF/F7666A-2 installed on a Lyc O-360-A1A with Lightspeed Plasma II electronic ignition has an rpm limitation against continuous operation between 2000 and 2250 rpm and restricted to above 2600 rpm only for takeoff. So, probably doesn't affect any, or at least very many, Mooneys, and certainly no J models.

I think there's still an awful lot of risk involved. I don't think it's a sure thing that this stuff will be successful, especially since there are still other efforts pending that may have more industry buy-in.

The rpm restrictions are in the Limitations section of the POH. While the placard only applies to the McCauley, the tach is required to be marked with the yellow caution range from 1600-1950. I have the Hartzell Top Prop, installed via STC, which also supposedly has no yellow arc limitations, but it still feels weird at those rpms so I try to minimize time spent there.

Yup. The cancellation (reduction, actually, not complete cancellation, in the case of anr), really does diminish the amount of power in the pressure waves reaching your ear canal. It sounds quieter because it is. If it wasn't it'd still be loud. The physics is pretty straightforward. I have tinnitus as well and it's been getting worse, I'm told mostly because I'm getting older. I doubt being in an airplane helps, anr or passive attenuation or not. You pick up some audio input just from the rest of your head/skull/jaw vibrating in the ambient pressure waves as well, and the most attenuating headset in the world doesn't stop that. For the anr in the Zulu 3 goes a long way toward letting me hear what I need to hear a lot better and reduce the amount of noise power getting to my ear, and that's about all I can ask for, I think.

Yeah, like that. And given the variations in dye concentration in fuels, both gasoline and turbine, it looks like there's potential for them to not be well differentiated visually if the dye concentration in the 100UL was low. I've seen some JetA with more dye that had a lot more color, so...? This is why I smell my samples, even if they look blue-ish. 100LL has that sweet-ish smell, but mogas or JetA stink. Even if there's not enough contamination to see visually, the smell is often distinct. Since the 100UL is still essentially gasoline, I'd expect to smell like avgas, at least I hope so. If it stinks, too, and even if it smells a little bit like JetA, that could be problematic.

In their Q&A document that Anthony posted earlier it says "Orange or Amber", and the pics in the pdf posted above show an amber color, not unlike the "straw" color of JetA.

I'm a bit worried about the color and how visually distinguishable it will be from Jet A. Maybe if it gets ubiquitous it can be changed to something more obviously different than Jet A.

Cessnas have a lot of trouble with the carry-through spars on many different models. Those are the spars across the fuselage that hold the wings on. Since those are significant structural members the ADs are important and can be expensive to repair if corrosion is found. The ubiquitous Piper PA-28 also has an AD on inspection of the wing spar attach points. On many PA-28s there is no inspection access to the required area so sometimes a new inspection panel is cut into the wing to allow access. I think generally Mooneys fare quite well as far as airframe ADs go. My hangar neighbor, an IA, was recently doing the annual on his Comanche and commenting about how he has to periodically disassemble the tail in order to gain access to the elevator control horn to do a periodic inspection required by AD. I think we get off pretty easy in comparison to some.

Sounds like you're a good way down the path already. I think what you're seeing is why most of the existing systems use GPS reference data for part of the correction. How to manage the sensor fusion seems to be the secret sauce in a lot of stuff like this, so best of luck with it!

This is the AHRS that is usually used with the stratux: https://www.amazon.com/gp/product/B06ZZCHBHT There are a number of USB GPS/Glonass/beidou/galileo receivers that are in the $15 range also available on Amazon. https://www.amazon.com/gp/product/B01EROIUEW adafruit is selling a really nice 9 DOF IMU with a magnetometer and temperature sensor for $20. The interface is I2C so it'll talk to just about anything. I don't know whether there's a library for it on the RPi, though. This unit is nice because it does the sensor fusion internally and outputs things like a gravity vector, etc., which saves a lot of development. https://www.adafruit.com/product/4646