PT20J

My position has always been that more testing was needed because we had one demonstration that showed paint damage and another that did not. The second video shows more extensive testing and also highlights a difference in methodologies (test panels submerged vs. fuel allowed to evaporate on the surface). It is evident that there is paint damage in the test that allows evaporation on the surface and I agree that this more closely replicates in service conditions. The effect on EZ Turn (aka Fuel Lube) is very concerning because the goo could clog carburetor and fuel servo components.

A way to find out would be to put an oscilloscope on the p-leads and compare the waveform with a known good one. There is nothing wrong with the dual mag, but they are notoriously tricky to set up properly. Cliff Orcutt told me that he was the only one at his shop that he would allow to touch them and when he started thinking about retirement he just quit accepting them. The problem is that as folks retire, a lot of institutional knowledge and experience gets lost. @jetdriven probably knows a good shop for dual mags.

This^^^^^ I have found Aspen tech support very responsive and knowledgeable. (Wish Garmin was as good). I might give them a call to confirm.

The ground straps go between the engine and the firewall. Check the latest version of the install manual, but I don’t think Garmin lists a compatible mag sensor for the dual mag. The one you posted might work and could be considered a minor alteration to the STC if it works. @N201MKTurbo might be onto something. You might also give Cliff Orcutt at Aircraft Magneto Service a call. He used to service the dual mags and is quite knowledgeable.

There should be two p-leads. Did you check them both? Also, check that the engine is grounded to the airframe. There should be a couple of heavy braided ground straps. I’m unfamiliar with this. Perhaps it was added due to radio interference or something. I woul try disconnecting them. It’s actually a 400 K-ohm resistor. There should be two at the back of the ignition switch where the GEA 24 wires connect to the p-leads on the ignition switch. I don’t think that's an option with the dual mag. You made two changes at the same time: overhauled mags and replaced capacitors. To troubleshoot, I would disconnect the capacitors since the mag seems to work.

I’d wait for the new part and see what happens after it is installed. It’s always possible that the spare part that may have been sitting on a shelf for who knows how long is defective.

Since the engine runs normally, the magneto must be functioning properly. When you say that a 1500 rpm mag check is normal, I assume you are getting a rpm drop when running on one mag indicating that the p-leads are functioning. Nonetheless, I would turn the ignition switch off at idle and make sure the engine stops running to test the p-lead connection. I’d check the p-lead shields to make sure they are grounded at the magneto. I’d check the GEA 24 connections. There should be a wire for each p-lead which connect to the ignition switch p-lead terminals through 400 k-ohm resistors and should use shielded wire grounded at the GEA-24 connector and the ignition switch. Where are those capacitors connected?

I'm going to have my M20J repainted. The original wing walk is a self adhesive non-skid material. I kind of like the uniformity of it's appearance, but it is starting to get bubbles under it in places. And, it has to be removed if the inboard fuel tank access panel ever needs to be resealed. The painter recommenced applying grit to the paint before it dries and then painting it black afterwards. I'm curious what others have done. Pictures great if you have them handy. Thanks.

Motor mounts, too.

Any instrument repair station should be able to fix it.

The schematic indicates that there is a connector (probably a knife disconnect) on the power lead to the floor lamp, so it would be good to check that it is secure. Then I would trace power from there back to the down limit switch NO wire. You know you have power on the C and NC contacts (because the down limit switch correctly switches power to the throttle switch depending on gear position), so it is possible that the switch is not making contact between the C and the NO contact. The down limit switch has two poles, one controlling the gear actuator and one controlling the lights. The pole controlling the motor seems to work because the gear actuator stops in the down position (if it didn't stop in the correct place the actuator ball screw would hit the mechanical down stop stalling the motor and tripping the gear actuator breaker). I would also verify that further depressing the plunger on the down limit switch does not activate the lights when in the down position before replacing the switch. If you do determine that the switch is bad, the replacement switch is a Honeywell 1CH1-6; the original 1CH116-6 is obsolete unless you find some new/old stock somewhere. A bad pole on the down limit switch would explain the malfunctioning floor and gear downlights, but not the gear unsafe light. So, there may be more than one issue.

I have no idea what fuel they can use beyond what is specified in the TCDS and the GAMI STC. If other fuels meet FAA airworthiness requirements, then I suppose they will get approved by STC or some other process.

Lots of companies make panels. eapanels.com is one. If you send them the old piece, they can replicate the shape and legends and powder coat it in color of your choosing.

That nose gear part is actually called a leg. The truss is the part the pivot bolt goes through. Usually, steering play is in the steering horn and various rod ends in the steering system. The leg in the picture appears unairworthy. There are dents in the tubes that appear to exceed the 1/32” max allowable.

The fact that the gear waring sonalert operates when the gear is up and the throttle is closed indicates that you have power from the Gear Warning breaker to the Gear Down Limit Switch NC contact all the way to the throttle switch. The floorboard lamp is connected directly to the NO contact on this switch and should be relatively easy to access. I would check that this light is getting power when the gear is down and that it is not burned out. The Gear Unsafe light gets power from the C contact on the Gear Up Limit Switch. This switch has contacts that are easier to access than the Down Limit Switch and I would check that there is power to the C contact when the gear is neither completely up or down. Also, check that the lamp lights when the Test button is pressed on the annunciator panel. The Gear Down lamp dims when the Nav lights are on, so you could cycle the nav lights and see if that makes any difference. Since two of the non-functioning lights are in the annunciator panel, there might be a fault here. There is no lamp test for the Gear Down lamp, so the only way to eliminate a burned out lamp is to replace it or swap it with a known good lamp. You can also remove the connector from the back of the annunciator panel and check voltage on the pins for the lamps to see if the problem might be within the panel. The circuits for these gear lights is pretty simple, but there are series diodes that could have failed.

I just stuff mine in the side pocket beneath the wemac on the pilot's side.

The Lycoming IO-360-A series (200 hp) has a compression ratio of 8.7:1. The Lycoming IO-390-A series (210 hp) has a compression ratio of 8.9:1. The Lycoming 0-360-A series (180 hp) has a compression ratio of 8.5:1.

I don’t have a picture of my throttle switch, but I’m pretty sure it is a Honeywell V3-1. Does the gear horn sound under the following conditions? 1. Gear up, throttle closed. 2. Gear down, no airspeed, gear switch up (bypass red button should also illuminate) Are you still not getting any Gear Down, Gear Unsafe, floor gear position lights inder any condition of gear up or down?

According to my paint guy, it’s the clear coat that gives extra UV protection and is resistant to Skydrol. I’m going to spring for an extra $3500 to get the new paint job clear coated. If it’s resistant to Skydrol, maybe it’s more resistant to G100UL staining and/or easier to polish out. He thinks it is also helps with corrosion. He paints the airplanes for a local flight school at Paine Field WA. They were having corrosion issues from deicing with isopropyl alcohol until he started clear coating them and there have been no issues since.

Or, they are milking the installed base because new sales are nil.

At least on the 100 series, the #8 screws on the top of the wing are threaded into tapped holes in the aluminum frame that only catch a couple of threads. For something that the manufacturer believes should be removed annually, rivnuts would have been a better choice. Some of mine have been drilled and tapped for #10 screws.

Per the simplified training schematic, this indicates that the gear down limit switch is operating properly.

That's the problem with greases: They are an oil mixed with a thickener and the oil and thickener separate over time if left to sit.

The RSA fuel servos originally used Buna-N rubber parts and a cure date decal was affixed to the servo. Back in 1980, Bendix switched to flourosilicone parts and issued a service bulletin. RS-76-Rev1.pdf

Can we pleeease stop discussing Skydrol. Everyone agrees on two things: 1) it's nasty stuff, and 2) it's not used in Mooneys. I would still like to figure out how to resolve the discrepancy between the two tests with one showing no affect on paint and the other showing severe paint damage. The discussion about o-rings got me wondering how long nitrile o-rings last in service. As near as I can find out, no one knows because there are too many variables. SAE AS5316 sets the shelf life for aerospace applications at 15 years. But I found a paper that suggests 7 would be more appropriate. https://www.sciencedirect.com/science/article/abs/pii/S0141391022003779 So, let's say 35 years ago the factory installed an o-ring that had been stored for 5 years. That means that the o-ring is 40 years old. Now suppose the fuel is switched to G100UL and sometime later the o-ring starts to leak. How can we know that that old/tired o-ring would not have leaked if it had remained on 100LL? I'm not arguing one way or the other, but merely pointing out that nitrile o-rings are life limited parts and perhaps they don't get replaced as often as they should.