PT20J

I see what’s going on. Although the GTN Xi can provide GPS guidance including VNAV all the way to the FAF, the GFC cannot use it after the CDI change. Unlike intercepting the localizer in HDG, where the GFC remains in HDG after the CDI source changes to VLOC, changing the CDI source from GPS to VLOC causes the GFC to go to default ROL and GFC VNAV is unavailable So, the work around would be to disable CDI auto switch and let the autopilot fly onto the intermediate segment with the CDI in GPS and then somewhere before the FAF switch to VLOC, APR, and whatever vertical mode you prefer. I wonder how the GFC 700 and 600 handle this? Skip

I will have to try it in the airplane. But I tried it on the GTN Xi simulator and VNAV worked all the way to the FAF even after it switched CDI source to VLOC. If you watch the GTN it is always showing magenta and using the GPS. When the CDI changes from GPS to VLOC coming out of the DME arc, the GTN scale changes from TERM to LNAV and VNAV TOD/BOD continues to display on the map. What PFD are you using: G3X, G5, GI 275?

Something isn’t making sense. Those are locknuts, so they shouldn’t loosen in service. Also, they have torqueseal applied to them to indicate if the nuts have turned and apparently they have not. Yet the flap has become so loose that it doesn’t fully deploy. I would want to further investigate this if it were mine.

Just follow the procedure in the manual and you will get the right answer.

I haven’t tried this (I cannot remember the last time I flew an ILS), but based on my understanding of the GTN, I don’t believe it should cancel VNAV when it switches from GPS to VLOC. The GTN GPS is always active and that information is what is displayed on the GTN. (That’s why you get the warning message not to use it for navigation when selecting a non-GPS approach). Changing from GPS to VLOC only changes the source for the external CDI (and autopilot). Switching the CDI from GPS to VLOC arms the autopilot to capture the localizer and glideslope but doesn’t change the lateral and vertical modes until localizer and glideslope capture. So, I would not expect switching the CDI to VLOC to affect any vertical mode (including VNAV) until GS capture. Skip

It looks like this was a reweigh. The CG calculation can get messed up if the procedure for determining the datum and distances to the wheel axels described in the POH and service manual is not used.

Now you’ve gone and confused it “Conventional” current flow is positive to negative. ”Electron” current flow is negative to positive. But we’re off in the weeds and probably not helping someone that just wants current to flow when the master switch is flipped on.

See if this helps. http://www.mikeg.net/hobbies/aviation/avionics/combined/King KY-196-197 Combined.pdf

Here’s where the factory put it under the right wing on my M20J.

I'm certainly not in a position to advise anyone, but I can tell you what I would do in this situation if it were me. There are four independent Mooney Service Centers in Texas plus the factory service center. I would call them and find one that is willing to check the gear rigging. I'd also get their opinion on what is necessary to ferry the airplane. From what I've read here, I suspect that just pulling all three gear breakers and flying it to a shop with the gear down would be fine. Skip

You cannot set the down limit switch correctly now if the gear motor has overrun. It needs to be set as part of the rigging check. I would just leave the whole thing as is for the mechanic to sort out.

The "jumper" wire is a flyback diode to quench the EMF created when current is removed from the coil and the magnetic field collapses. It's polarity is important. Your description of the symptoms sounds more like a weak battery than a solenoid. Skip

I think we may be overthinking this. Here are the facts as I understand them from this thread. 1. The gear has been operating normally since the OP purchased the airplane recently. 2. After a bounced landing, the gear unsafe annunciator illuminated and the gear actuator breaker popped. 3. Upon inspection, it was found that the gear down limit switch mechanical actuator (paddle? Mooney calls it a lug) was loose. (It would be nice to have some pictures). 4. The floor indicator shows that the gear is fully extended. Given the above, a likely scenario is that the gear fully extended normally before the landing. Upon landing, the gear down limit switch lug moved (maybe it wasn't tightened properly?). This caused the motor to run until it hit the mechanical down stop (it won't turn far -- maybe not even a full revolution) and jammed which caused the breaker to trip. If the preloads were correct before the incident, they will still be correct, or maybe slightly higher because of the motor overrun. There is no reason to think that the gear is in an unsafe position, if all the above is true. Checking the nose gear preload requires partially retracting the gear, and since it is most probably safe now, it might be best not to mess with anything. Obviously, the best thing to do is jack it up and have a mechanic check the gear rigging and readjust the down limit switch. Skip

My M20J uses a Electroswitch SA1RV20 with a SW53AA2 button. Mouser had stock in 2021.

I should have asked about the floor indicator. If it is aligned, and the preloads are properly adjusted, then it should be safely down. If something is amiss with the down limit switch the motor can overrun and jam and that would trip the breaker. The proper thing to do is to put it on jacks and check the rigging according to the Service Manual.

Hard to tell from your description what is going on. Usually the thing that pops the gear actuator breaker is the emergency gear extension lever being engaged. But you said this happened after landing and nothing should be running then. From your description it sounds like the gear is not currently fully down. I would get it on jacks and check it out thoroughly. It didn't collapse when you taxied it after landing, so there must be some preload left on the gear, but there is no telling how much.

Hmm. It reads zero when disconnected and full s scale when connected. Sounds like the gauge works. Probably a short in the wiring, or a bad float.

A few years ago at MoomeyMAX, the company rep said they work best on 6 cylinder engines and don’t make that much difference on four bangers because the exhaust pulses are closer together on the sixes.

I wonder if the old strobes were better shielded because they knew they were noisy?

If it is zero then it is either a broken connection somewhere or a bad regulator. I would next check the voltage at the field terminal of the regulator.

My shop told me that they have had to rewire every Cessna with wingtip strobes when installing a GMU 11. They just replace the wire with shielded wire -- they didn't need to replace any lights.

Did you once have a KCS 55A? I believe some installations required a 400Hz inverter. @Jake@BevanAviation would know.

After changing the bulbs, it’s a good idea to check the alignment. The procedure is in the manual. Basically, you measure the aim points at the specified distance and mark with tape on the inside of the hangar door. Mine were off quite a bit.

It is definitely less expensive to keep the old stuff running. There is so much used equipment out there from panel upgrades that it’s not hard to find replacements, and most old stuff can still be repaired. The problem is that you never know which old thing is going to fail next, or where. If you fly mostly locally for $100 hamburgers the reliability may not be as important. But if you travel a lot, reliability can be a big issue. And for me, playing whack-a-mole with the panel became tiresome.

I got mine from Frank Crawford at Mooney.