Ilya Haykinson

Thanks folks for the suggestions. My mechanic thinks that there was some continued fouling in the plugs, which resulted in one cylinder producing no or insufficient power. We might have not sensed this as roughness, but it would be enough to produce less than full power. It also works well with the sudden return of power in flight -- whatever was blocking the spark could have rattled out / melted / whatever which would bring the spark back into life. The "cable for prop not traveling as far as it should" is a reasonable idea. The cable was certainly working -- we were able to adjust the prop down and back up, just not all the way to 2700. For the MP -- I don't recall, unfortunately. It did seem a bit low to me at the time, but the airport I was departing from was at 3,000ft, and it was a warmer-than-standard day, so I didn't expect it to read the same as at sea level. It could be mags. They were on the plane when we purchased it, and I don't recall how many hours on them at the moment. Carb heat was definitely off. I think as a matter of troubleshooting, I am considering doing a run-up followed by high speed taxi to see if I have a repeat while developing full power and moving through the air (at least below takeoff speeds). If both of those show that everything is behaving as it should (full RPM, normal MP, etc) then the problem was likely transient. If not, I'd pull the plugs and check them, and then repeat.

Sigh, I know... Coming soon. Possible, though I would imagine a spark plug wouldn't "fix" itself suddenly after some number of minutes. Fuel flow registered fine. We tried with and without fuel pump. I don't remember precisely (co-owner bought the plugs and managed their install), but I believe we use fine-wire. I would imagine in a stuck-valve situation we'd get an extremely rough engine, with one of the cylinders producing no power. We didn't have any roughness. That's a great idea. I can imagine that if we weren't getting all the air in that we wanted, we'd get some power but not all of it. Like, say, if there was something partially blocking the intake that later moved -- power would return immediately. We should have tried alternate air. After we cleared the plugs at the end of the runup, the mag check came back clean. We did try a mag check while it was running under-powered, but there was just a normal small drop on each mag. After power returned we tried it again, and then (half an hour later, after landing) we tried it with the engine at idle too. Everything was smooth. Well, I guess one step is to figure out whether this issue comes back, but I'm going to chat on Monday about his recommendations.

When flying my 1968 G model the other day, I had a situation which seemed unusual. I flew to an airport about an hour away, flying without any problems. After landing, I must have not leaned the mixture as I taxied to the ramp. After engine start for the return trip I leaned, but upon performing runup one of the mags yielded a rougher running engine and a significant RPM drop (around 250 or more). I leaned it out, opened the throttle and brought it to 2000 RPM for a half a minute. Checked again, same drop. Repeated 2000 RPM, same drop. Then I brought it up to full power, and after 30 seconds went back to 1800 RPM and the check succeeded. Fouled plugs cleared, though the CHTs went up to the end of the green and possibly closer to redline. I let it cool down a minute. On takeoff, however, the airplane produced what felt like less power. It took off and climbed, but the climb at 100 mph was far less fpm than expected, and I would never develop more than what looked like 2450 RPM or so. Maybe 2500, but I'm used to having the prop reach closer to 2700 and requiring me to pull it back to 2500 instead of struggling to produce the full power. Right seat from me was an experienced instructor and mechanic, and we worked to troubleshoot this while also deciding whether to turn back or continue -- we could climb at 500-700 fpm, possibly due to updrafts, but with lower airspeed and with noticeably less power than expected. We tried adjusting throttle, mixture, prop to no avail. When we leveled out ten min later, power was still lower and thus airspeed was about 15mph slower than expected. Then about 3min later it felt like power just came back, airspeed increased, etc. The rest of the flight was uneventful. The only thing that for me would explain this would be that we had run the engine hot enough during our runup that it didn't want to perform after takeoff when quite so hot. But I don't have a logical explanation for how this would happen. Does anyone have thoughts on what could have happened? I have stock engine instruments so I have little insight into what it was doing -- oil temp and pressure we're fine, and EGT -- while hot -- was not unusual.

Apparently there is a process you can follow to block your tail number: https://www.nbaa.org/ops/security/asdi/ This said, there is nothing you can do to completely hide yourself since you broadcast the tail number as you fly, and anyone with a $30 radio can pick it up within a certain radius. But if geeky spying coworkers with at home setups are not your main worry, then you shouldn't have to worry. Sent from my Pixel XL using Tapatalk

As long as you are flying in an area where ADS-B usage is required, I don't think that you have a choice. In theory you could go outside a Mode C veil and fly with your transponder off, but that would decrease safety for others while giving you extra privacy. I think there is some way to turn the reg info private on places like FlightAware though. Sent from my Pixel XL using Tapatalk

Thanks, much appreciated. I'll give Lasar folks a call to see whether they have ideas. I agree that relays are easy to swap out, but our IA is requesting the same part so for now I'm stuck looking for that. Not sure how others deal with it -- I agree that a solid state relay would probably work wonders here, but that's not the same as original equipment... and I haven't seen any STCs for that. We have the service/parts manuals too, thanks for the note on the 800185 part number (we have the other unit from Safe Flight, listed on the same page).

I am not sure if the K would have the same part. The specific part is a Dual Warning Horn P/N 283, it's a sort of a silver box with two speaker grills and seven (I think) wire connectors on top.

It's a manual gear, so it's not a piezo horn but a pair of really loud ringers inside a box. The box also has a capacitor, transistor, a few resistors, and a relay. From our testing, the relay doesn't toggle correctly...

My four partners and I just bought a 1968 M20G. It's in a good shape, and we knew the former owner and some of us have flown in the plane a bunch before. In the (owner-assisted) annual, we so far discovered that the gear warning horn doesn't function quite well. Specifically it'll sound once for a second and then stop. After taking it out, we think that the relay is malfunctioning. It doesn't look like acquiring this is easy at all. On the odd chance someone here has one, I'm looking for either the relay from the unit, an Allied Controls T154X-387, or the entire Safe Flight Instruments Dual Warning Horn P/N 283. Any suggestions as to what my options can be, other than purchasing an incredibly expensive unit from Safe Flight Instruments?