druidjaidan

There's so many part numbers involved and it's highly unclear to me what makes a compatible v-band or not. My part number is 646534 (at least according to the last replacement log). That RAM one seems to be a replacement for 653332. The mooneyspace thread says it works with GB and LB engines, but the RAM PMA only indicates the -LB engine. The parts catalog doesn't seem to help, and it seems like there are a ton of versions of this clamp =/

Not sure what to make of the mag. That line running to the mags definitely looks to be a pressurization line, but the dataplate says it's a 10-79020-18 and not a 10-79020-118 (which as far as I can tell is the pressurized version). I'll have to poke my mechanic to see if he can explain it. That said, the picture of the actual sensor resolved the whole thing, thanks @rklems. I had seen a strange metal tab sticking out of the mag, but didn't connect that it was sensor connection since it looked nothing like the images online. Once I saw that it was really clear what had happened. The only thing holding that together is the rubber sleeve and the bulge on the end. Someone had decided to pull it out instead of cutting the ziptie and disconnecting the molex during a recent maintenance. That particular mag was just replaced after the previous one failed, and two days later the alternator failed. Either of which I could see having the mechanic needing to pull that out of the way. When the put it back they didn't push it all the way down (like in the image) and likely just pushed the head in. That worked it's way out after 10ish hours of flying. Either way it's reattached now and everything is good to go.

Going to go look again today, I might have missed it being changed over and just didn't check. I didn't find it in the logs, but that image sure looks like I'm wrong. It also makes me even less inclined to overhaul anytime soon. My records still indicate this is a GB engine, but maybe this has had more of the LB conversion than I thought.

I'm going to check again on the mag. I don't see them being replaced in the logs with a pressurized version, and my engine is a GB from 79 so I don't think it was changed over to pressurized mags. But that sure does look like a hose going into the mag now that you point it out And that sensor looks a lot what my wire and I saw something on the mag that looked like I imagine that does under the shrink tube. Maybe it just pulled out? I'd expect that to be crimped in I guess.

I suspect I'm going to find something very rigged, considering the whole thing I'm holding is a set of butt splices. I looked in my logs and the mag is 10-79020-18, the unpressurized mag it looks like. I suspect the wiring is all the same it's just sensor end that's different. I suspect that for whatever reason when they where installing the EDM they ordered the wrong sensor, then cut off the end and wired it up to an existing sensor from whatever was in there before I guess. I need to get back to the plane for a better look to be sure, I didn't know what I was looking for yesterday when I had it apart. I suspect I'll find something loose from the sensor, might just end up ordering a new one to clean this up instead of adding yet another butt splice.

TSIO-360-GB. Local mechanic says "they are rare but we can get them in, I won't do the inspection as I've never seen one pass we only replace them". My normal mechanic says he's had it on backorder for me for over a year and has signed off two annuals with it. I'm due again soon for the recurring, and I want to do my own due diligence on the part lookup. My logs indicate the part number should be 646534 (when it was last replaced). Continental doesn't show any superseded part numbers so that means it's the right part? They list Boeing as the supplier (with no supply of course). Spruce has it as "special order". I know these things are apparently completely unobtanium, but I want to make sure of that before I firmly tell the local mechanic to go pound sand. I'd also like to get my hands on one before it inevitably fails an inspection.

Just the JPI.

No sooner do I get the broken through bolt replaced and another random thing breaks. I got the broken through bolt replaced this weekend (see other thread for that), did a nice long run up and then flew near the airport for a bit before finally heading out on a short flight to a nearby field for lunch. Everything was going perfect, engine working great. Feeling pretty confident that the through bolt failure didn't have any latent issues. Then I head back from lunch. A couple minutes after departing my EDM 900's tach display starts oscillating wildly. At first I'm a bit panicked, did something go wrong? However, nothing sounded or felt wrong. If my RPM was acting as crazy as the instrument it would have been obvious. So I landed and....the RPM started working. Pulled the cowl an started looking for the RPM sensor. Found the cord and traced it forward...and realized it was just completely snapped off. It must have just been touching, and just the air through the cowl was making it move around and sometimes make contact. I'm having trouble trying to figure out what actually will need to be replaced and I like to know that before I call in the mechanic. Since the part number 420807 on the wire is the pressurized mag part to me it looks like someone cut the end off a pressurized mag JPI sensor (I don't have pressurized mags afaik either so not sure why that part) and then crimped another wire onto the end? This doesn't really look like https://www.aircraftspruce.com/pages/in/probesandsenders_zjpi/jpi10-05459-61.php. Sorry, It's a little hard to tell what's going on in these photos, but I'm holding the broken off spiced wire. I had trouble finding where exactly it broke off of tbh. I'm assuming one of my mag will have the end of the sensor in it.

That's kinda exactly where I am at for sure. I think the odds that it spun are low. The engine builders I spoke to both felt that if it did spin we'd have a rapid (within minutes) engine failure due to restricted oil flow. My current opinion is that I'm sitting on Schrodinger's cat. Either the bearing spun when I warmed up the oil for the oil change or it didn't. If this was a low time engine it would be worth doing the IRAN to look inside that box and making sure it was all in order so as to not risk more damage. This is a high time engine though, and a GB. I'll be sending it in to Continental to exchange for an LB within a few years anyway. If all I'm risking by fixing it is that the cam might get further damage on startup, that math seems to point toward fix-it, run it up hard, and fly it with maybe a few extra oil changes to monitor for metal. If that bearing spun on last operation that cam is likely unserviceable anyway. The biggest uncertainty in my mind (as I'm not an expert): is there another failure mode that isn't as obvious as "bearing spun, oil flow obstructed, engine die". I have no interest in taking a risk that this engine is a timebomb and would rather just overhaul if there is any reasonable chance of that.

I've gotten quite a few opinions from various engine builders and A&P/IA's over the past few days. Continental was the only one that felt IRAN (and by default overhaul due to age) was needed. The rest basically were like: if the bearing was spun it would block/restrict oil flow and you'd know very quickly (as well as ruin the engine). All said they would/had safely replaced thru bolts in similar situations and didn't have concerns about doing so with mine. The specifics varied between just replacing the bolt to re-torquing all, to replacing the bolt and all studs on that cylinder + re-torquing all. The biggest fear is that the loss of that bolt caused the main bearing to spin and the engine is toast as it is. Assuming I trust the engine builders and A&P's are correct, if that happened we would know during a nice thorough run up. If that run up destroys the engine, so what we would overhaul anyway (and I'm likely to reman this time since it's GB engine). The balance of that is if they are failing to mention some risk of near future catastrophic failure, it isn't really worth risking my life over a few hundred hours more we'll likely get out of the engine. They were pretty adamant that wasn't a risk though, the risk was the next time we start the engine the oil won't flow and we'll toast the engine within minutes.

Continental Tech Support says: Given this through bolt provides clamping pressure to the main bearing they recommend IRAN and I might as well overhaul it since it's been more than 12 years.

Double checked the logs. Last cylinder work was quite a while ago 10/14/2014 at 962 TSMOH. Last annual 6/19/2025 we were at 1567 and we've probably flown 90ish hours since then. Calling the local mechanic on the field tomorrow. Unfortunately mechanic availability is absolute crap at KPAE so I'm likely down for quite a bit for something as severe as this =(

No recent work, at least since I've owned it. Around 1550 hours on the engine. I'll check logs for any work before I owned it.

A bit more context on the engine.

Sheared side of the bolt is cylinder 6 toward the propeller. The backed off side is in front of cylinder 5