DC_Brasil

I actually don't recall... will have to check that.

My first guess was a bad battery. Will check that for sure!

Would that explain the crazy ammeter readings? Sorry but I am very inexperienced with electrical circuits.

Hi Eric. I did a mag check before takeoff and in flight and it worked fine. Engine ran smoothly and EGTs responded properly to the single mag.

Let's get the collective wisdom rolling My M20J is fresh out of the avionics shop after installing a G3X panel. Last week when I flew it, the R wing fuel gauge stopped working. Well the fuel senders are old and I am contemplating a switch anyways. The very next flight, when I tried to start the engine I turned the key the plane seemed like the battery was low. I thought it was odd but maybe I spent a little too long updating the navdata with the engine off. I started it with an external source and went flying. Everything seemed normal so I took it on a 2hr XC flight. Today, flying back home I experienced the same behavior and had to use and external source to start up. Now, both COMM radios had an interference of a quick rhythmic "popping" sound. Additionally, in cruise I could see the ammeter was showing some crazy readouts, going from -30 to -290 amps!!! After I landed the ammeter showed a reasonable +2 amps. I tried turning on and off various systems and lights to see what I could find but no clue. Nothing particular happened. I suspect something is shorting the system and draining the battery. Perhaps the fuel sender line (it may have nothing to do with the electrical problem but what the hell)? Any thoughts? Here are some pictures.

Yes, that's personal but you actually get used pretty fast. The upside is that the G3X is as left as possible (and in my case, as high as possible) freeing more panel real estate for future upgrades.

The original Gear Override switch in my plane was to the left of the gear lever. I also thought it made sense to put it below and save some lateral space. Yes, the Cygnet switches were placed in the same mount. Now I need to try and fix the R fuel senders. New picture, flying today to Rio de Janeiro (SBRJ). Navigating with the G3X and GFC500 is a breeze!

Finally in the air! After solving some quirks after the upgrade, my J is finally flying. Just loving the new panel and especially the GFC500 autopilot. It reaaaaly makes things easier. Next steps for 2025 should be a new GPS, transponder and most likely CiES fuel senders. After a turbulence bump my R fuel sender stopped working (it was working fine in previous test flights).

Great webinar from Mike Bush about valve sticking. https://youtu.be/7ohsVvYbAaQ?si=nLwJ9cTg9ANzh3kE

Can you share the video and perhaps a picture of how your left aileron looks now? I am having the exact same issue: a very intense right roll tendency after the shop rigged everything according to manual specs.

@Stanton R thanks for the warning. The servos had indeed been rigged the wrong way and the YD behaved as expected: Dutch roll. However two other things were wrong during the test flight and the shop is assessing the issues: 1 - whenever engaged, the Autopilot commanded very aggressive right turns, even on ROLL lateral mode. 2 - the G3X tachometer is showing less than the real RPM. I guess this can be some incorrect config of the magneto type (Rated RPM is 2700 and the G3X is showing 2470). Having these checked today.

@Stanton R thanks for the heads-up. I will definitely talk to the mechanics about it. Wednesday I was there to test everything. Pitch, roll and trim controls worked on the ground. I didn't test the YD, but will do tomorrow morning. Do you have any suggestions on how to actually test if the YD is working correctly? I have never flown with YD.

Almost ready! Went to the shop today. The idea was to review all installation and do a thorough runnup and a quick test flight with the mechanic to review the GFC500 autopilot. All avionics working but we had a malfunction with the voltage regulator. Having it checked the next couple of days and see if we can fly the plane Saturday morning. However, we got to spend some time playing with the new screen. The G3X is indeed a very nice piece of equipment.

Thanks everyone for the very useful insights. I'll get right on it with the guys at the shop.

Hello everyone. My M20J is in the avionics shop finishing a panel upgrade. When the guys went to drain the fuel tanks to calibrate the fuel sensors with the G3X, the fuel drain sump valves on both wings had cracks. Since they are hollow screws and rather fragile, I'm guessing the previous guys that worked on the plane may have over-torqued it when screwing the valves in place. These were SAF AIR 53S fuel drain valves. The SAF AIR 53S are direct replacements for the F-391-53S original fuel drains. I bought a couple of F-391-53S from Aircraft Spruce and they already come with new o-Rings. When installed these drain valves were very slowly leaking. It is a very slow and subtle leak, not even dripping. The drain valve gets wet with fuel. The shop tried to use two o-rings but the slow leak remained. Anyone has any ideas how to mitigate it? It is the correct piece, correct PN with a brand new o-ring. Should be a good fit, right?

Hello! My M20J is finishing the panel upgrade next week. I'll have a freshly remo ed and working VSI for sale. I live in Brazil but could check how much a FedEx or DHL shipping would cost if you're interested. Pm me.

What a sweet setup!! My plane's is in the shop for un upgrade and, since I had a GNS430 and had read great things about the GFC500, decided to go with a G3X setup (1 10" screen + G5 backup). My reasoning was mainly because of service and support availability but also looking at upgrade plans. I live in Brazil and it will be way easier to find support and service for Garmin than any other brands. Additionally, since my budget didn't allow for me to upgrade the GPS now, going all Garmin will make it easier in the future (albeit somewhat expensive) to replace other parts of the panel. And as @Pinecone wrote: having the panel made the way YOU want is part of the upgrade fun :-)

I have found that PDF. I am worried (maybe unjustified, though) because I suspect Brazilian aviation authority (ANAC, our FAA) will need to update my CA with the new GW. My A&P said that they need to file a request and add supporting documents. My worry is that when someone sees that both the Service Letter and the M20J Type Certificate Data Sheet tell that the GW increase is approved when in compliance with Mooney drawing number 940071. I am concerned they'll look at it and ask:, Ok, where's this drawing in your request? We don't see it, so we can't verify the procedure has been followed.

Would you please ping them in this post?

Soooo... anyone has the Mooney drawing number 940071? ahahahahah this seems to be the biggest mystery in all of this.

No. You are either certified for a 2740 GW (MTOW/MLW) or 2900GW. See the M20J Type Certificate Data Sheet screen shot below. https://drs.faa.gov/browse/excelExternalWindow/6EA0F05ECCA8304486258305006833CF.0001

It is actually the diameter of the steel tubular structure that is bigger, increasing the structural strength of the aircraft. Some S/N rolled out with that modification but were still certified for 2740lbs GW. Those are the planes that can get the GW increase.

My Serial Number actually shows it as being manufactured in 1989, but the documents were stamped 1990. Perhaps it rolled out the assembly line late 1989.

I am a new owner of a 1990 M20J and the serial number falls within the approved models for the GW increase. However, the Service Letter (and the M20J Type Certificate Data Sheet) tell that the GW increase is approved when in compliance with Mooney drawing number 940071. I tried to find it online without success. Then I emailed Mooney. This was their response: Thank you for the Inquiry – Yes, Mooney does not send out drawings, unless they are purchased as the kit. For lead times, availability, pricing and to purchase parts (including technical manuals), you must order through an Authorized Mooney Service Center (must be a Mooney Service Center), click here for a listing of MSC’s https://www.mooney.com/contact-2/#map Does anyone here have this Drawing? From what I have read (including this forum) there is actually nothing more than these steps for the GW increase: Reconfigure the airspeed indicator's markings to reflect the new limitations (should be easy as I am installing a G3X+G5 right now) Substitute pages in POH with AFMS Comply with Service Bulletin SB M20-252 Any of you actually did this GW increase on your plane?

I was watching a video on YouTube and a pilot was going through his preparation for a long trip and that made me wonder. As a new owner of an M20J, I'd love to hear some of your ideas of what you absolutely will bring with you in the plane if you're going on a long cross country trip with the family. What is in your lists?