DCarlton

Update. I'm no expert; just trying to connect the dots. It looks like AD 2024-21-02 is an expansion of AD 2017-16-11 which points to LYC SB 632B for action. SB 632B provides Table 1 with serial number of affected engines. For overhauled engines, Table 2 provides shipment dates for suspect bushings. IAW para 1.B, I've consulted with my overhaul shop to determine if I may have suspect bushings. Again. I'm not a mechanic or an expert. Just an owner trying to get ahead of a potentially painful problem. My engine has less than 200 hours.

Just checked my engine logs. My engine overhaul was signed off in July 2016. The LW-13923 bushing were replaced during overhaul. The FAA has a concern about bushings shipped up until 11/17/2015. So now I have to wonder whether the overhaul shop used up the 2015 bushings they had on the shelf before they started my overhaul. I may have squeaked by..... or not. Gonna email the shop and see if they keep those sort of records (when parts were received). I'm planning to start checking for particulates and doing oil analyses anyway just to feel "better".

Great questions but I'd still like to know why the bushing were "bad". Wrong alloy? Not machined to correct tolerances? Why wasn't this caught during QA? How did they confidently isolate the production lots in question? What steps have been taken to make sure the new bushing don't have any QA issues? To manage this issue the FAA has to know the answers to these types of questions, otherwise, they're shooting from the hip. I wouldn't want to crack open a good engine at significant cost without more details. Guessing there's a detailed failure analysis report somewhere. I asked for it; no idea if I'll see a response.

So... which bushing is failing? The one pressed into the rod that's part of the rod or the ones that go over the piston pin?

And how do you know you're replacing the bushing with better bushings with adequate QA if you don't know what's wrong with the ones you're taking out. No details provided (although I haven't read the LYC bulletins yet). Maybe it's there...

I was wondering that too. I’ve had similar main bearing issues with a boat engine. Added to the list. Gonna email the FAA. Update: Sent the FAA POC several questions. Will advise if I see a reply; guessing they are swamped.

Will the FAA respond to questions? How many engines have failed? How many hours were on the engines that failed? What is the root cause? Was the wrong material used; were the bushings not manufactured to correct tolerances etc? How did they isolate the production lots in question? Do the bushings degrade suddenly or fail slowly over a long period (years)? Explain why a periodic oil inspection is sufficient to catch degradation early enough to prevent failure etc? How do you adequately inspect a connecting rod bushing in one work hour?

My engine was overhauled around 2016. Planning to pull the logs soon and then sit down with a mechanic next Friday to review findings if any. Was just about to drop serious $$ on bladders in Dec / Jan. Hoping I escape this one. Like Rosanne Rossana Danna used to say...

I'm planning to install one this winter when I remove the interior side panels to replace the fuel gages. A good time to run the wires.

Attached is the feature list from the AV30C install manual. Note the required interface column. You have three screens to choose from that are configurable in addition to the traditional AI display. I have yet to settle on the optimum configuration for each screen. Density altitude is great to display prior to take off for example. Other options may be better for climb and cruise. Note: I was surprised to see the DG Tape show up as an option in the AI configuration if a magnetometer is not installed. I believe an external mag is required now to use the AV30C as a DG. It almost seems like an oversight. It would be very handy to have an accurate DG tape though. With so many sources of heading information, that don't always agree perfectly, having a no fuss DG tape display would be helpful. Otherwise, I trust my compass as ground truth. AV30 FEATURES.pdf

I didn't study this entire thread; just quickly adding that an AV30 was installed in my F this past summer in the AI position with a GPS data interface to my GNS (that was by far the hardest part of the install; getting the RS232 wire/pin added to the GNS harness). No complaints; I'm impressed given the price of the unit. Just don't plan on depending on the DG indication without an external magnetometer. The screens are highly configurable and the DG heading readout is an option on one of the screens even if locked in the AI configuration (as for certified aircraft). I'm hoping to add a magnetometer down the road; the DG heading could be handy.

Curious what it will do to the Piper market even though it's a lot of hours. There's just something about spar ADs... I'd be the kind of guy that would cut the FAAs limit in half and still worry about it. If I ever auger in, I want to make sure it's my fault and not the airplanes.

There's a very very old Mooney Service Bulletin that covers this exact topic. I'll see if I have it in my files. I'm starting to suspect a problem with my compass readings.

If my set screw is not tight, it will move a little side to side on the shaft. Always has. That tells me if you tighten down the set screw, there's a significant point load at the screw. I'll bet many are that way; otherwise it would be hard to get the yoke on and off the shaft. I think.. I'm no expert.

Guessing the engineering would be easier on the new machined part if properly fitting to the shaft, than trying to reverse engineer the old cast part and figure out the safety margin and potential causes of failure.

Interesting that there's a crack in the set screw hole too.

I'm no expert and I haven't done any mathematical analysis, but it's always troubled me that the yoke rocks on the shaft if the set screw isn't tight. There's opportunities for stress at the pin that holds it on, and there's more opportunities for odd stresses where the set screw bottoms out on the shaft. And.... most folks pull with their left hand creating side loads on the whole assembly. When I'm pushing or pulling hard I try to use two hands (because I'm paranoid; I've played out in my head how I would grab the right yoke and get in the right seat). Now if I designed an aircraft it would never get off the ground it would be so over designed. With that said, I've fixated on that yoke attachment as long as I've owned the plane; never liked it. Gotta wonder how you do an analysis on a cast part like the yoke and what causes failure; is fatigue an issue with castings; how do you ever NDT or QA a casting? Is there some sort of internal corrosion that occurs? To expertly analyze this connection between the shaft and the yoke and the safety margin isn't easy. Would be nice if Mooney could produce enough yoke upgrade kits to make them "affordable".

I just installed the Mash washers on my fuel caps. I'm satisfied.

Just FYI, I don't even think my system has a name. Jerry Walters installed it in Tulsa. Basically he took the PC system, and added the TC100EVT, DG Adapter, and DG. It tracks the DG heading bug. If it has a name, I'd have to dig it out of the records. The only thing added to the instrument panel was an on and off switch for the heading bug and a pneumatic cut off switch that does the same thing as the one on the yoke .

Do they publish NOTAMS for these events? No chance of finding out after you land?

15 years ago when Brittain was still servicing airplanes in Tulsa it was 2-3 grand and a day or twos work. Now it’s a matter of understanding exactly which system you have and then finding salvage parts to do the upgrade and someone willing to do the work. Mine only tracks the DG. Mine uses a TC100EVT turn coordinator with inverter, a DG adapter and DG with a heading bug output. I think it’s a 4000-D1. The DG adapter is hard to find. The turn coordinators can still be overhauled by Kevin Westbrook at Porter Strait in Tulsa. Kevin might be able to ask a few questions, figure out what you have and then tell you what parts you need to find on the salvage market. I’m no expert and I’m only guessing but I suspect the output from the 430 that drives the CDI will drive the Acutrack.

If I remember correctly there is someone on MS that’s been waiting 14 months for a six figure AF1B Lycoming Engine overhaul and they still don’t know when it will be completed due to parts issues.

Uh oh. Now I've gotta go read about this thing called "VARMA".

Based on experiences, I'd like to know and understand in advance what will be wrenched on or disassembled and why, and I'd like to be there for final inspection when that work area is closed out. I'm caring less about assisting these days, but I'd prefer complete awareness of what work is being done and what quality assurance steps are taken to make sure the work is done properly. Once bitten, twice shy...

I'll have three Shaw caps with Flurosilicone O-rings and Marsh washers for sale early next year. Expect to receive bladders around the first of the year.