Lycoming Connecting Rod Bushing AD 2024-21-02

[A64Pilot]

See I’m not a firm believer in oil analysis as an indicator of engine health as that’s microscopic. In managing up to 24 helicopters for I guess 15 years or so, not once was oil analysis the trigger for component removal, it was always chip lights and chips etc on the detector and or filter, and often the amount of metal in the oil was scary, draining it it looked like there was silver paint in the oil.

Army pretty much invented SOAP (spectroscopic oil analysis) the first oil analysis lab was in 1961 at Ft Rucker Al. So they have an unbelievable database.

What I found oil analysis to be excellent for was determining the condition of the oil, especially Diesel’s for soot, fuel dilution, water and coolant etc.

I’m not saying don’t do oil analysis if you desire to do so, just I never got a recommendation from the Lab telling me to pull the component out of service prior to me making that decision based on visible metal particles.

I’m just saying that it’s not the ultimate indicator of engine health that’s it’s being marketed as, it’s just another tool, but it is the absolute best way of determining the condition of the oil itself, for that it has no equal.

I assume that the FAA and Lycoming don’t either as they don’t reference it in the AD as an AMOC

 

Edited November 8 by A64Pilot

[1980Mooney]

58 minutes ago, A64Pilot said:

I can’t imagine a piece of bronze coming from the small end bushing being 3/16” without the bushing pretty much coming apart.

Pieces of metal even 1/16 would have me very concerned.

I’d expect the failure mode to begin with small flakes that progressively get bigger, but good Lord 3/16” “chunks”? 

Am I the only one that never sees metal in their filters? I need to quantify that as I sometimes see a very small amount iron so small it feels like grease on the magnet

I am with @A64Pilot.  This entire classification criteria seems ridiculous.  “Greater than 3/16 inch” is a “chunk”. That means a piece 3/16 inch even is a “chip”.  So if your engine is making metal and you only find a single “chip”, less than 5 metal particles on EVERY panel/pleat of your oil filter or less than a 1/4 teaspoon of metal the you are “OK” ….

Remember that these will be the pieces that you find - what about the ones that you don’t find. - the ones that gravity traps and are lodged in the case. 

[DCarlton]

1 hour ago, A64Pilot said:

See I’m not a firm believer in oil analysis as an indicator of engine health as that’s microscopic. In managing up to 24 helicopters for I guess 15 years or so, not once was oil analysis the trigger for component removal, it was always chip lights and chips etc on the detector and or filter, and often the amount of metal in the oil was scary, draining it it looked like there was silver paint in the oil.

Army pretty much invented SOAP (spectroscopic oil analysis) the first oil analysis lab was in 1961 at Ft Rucker Al. So they have an unbelievable database.

What I found oil analysis to be excellent for was determining the condition of the oil, especially Diesel’s for soot, fuel dilution, water and coolant etc.

I’m not saying don’t do oil analysis if you desire to do so, just I never got a recommendation from the Lab telling me to pull the component out of service prior to me making that decision based on visible metal particles.

I’m just saying that it’s not the ultimate indicator of engine health that’s it’s being marketed as, it’s just another tool, but it is the absolute best way of determining the condition of the oil itself, for that it has no equal.

I assume that the FAA and Lycoming don’t either as they don’t reference it in the AD as an AMOC

 

Don't disagree at all.  I'm just curious now and I like data.  This issue is a bit of a science project.  

[PT20J]

Here is the independent analysis of the failure mode taken from the 2017 letter to the FAA signed by Mike Busch and others. (I posted the entire letter earlier in this thread). I don’t know much about bronze bushings except that I tried to ream one once for a non-aviation project and it broke into little pieces, so I gather it’s a pretty brittle material.

[A64Pilot]

1 minute ago, DCarlton said:

Don't disagree at all.  I'm just curious now and I like data.  This issue is a bit of a science project.  

After I posted I went back and re-read your post. I saw where your using it as another tool

I guess I sort of jump to conclusions whenever oil analysis comes up. I’ve even had people tell me they don’t inspect their filter, they do oil analysis, it’s so much better.

You may think me nuts but I’m doing oil analysis on my Motorhome but not my airplanes. The engine I have in the Motorhome used an excessive amount of EGR to pass emissions, so it is pumping soot into the intake, but also to burn off the DPF instead of a separate injector they got smart and inject fuel in the exhaust stroke to put raw fuel in the exhaust that way, unfortunately that also puts raw fuel in the oil, this engine has a rep for “making” oil, which is fuel in the oil of course.

So I’m trying to establish an oil change interval 

[A64Pilot]

13 minutes ago, PT20J said:

Here is the independent analysis of the failure mode taken from the 2017 letter to the FAA signed by Mike Busch and others. (I posted the entire letter earlier in this thread). I don’t know much about bronze bushings except that I tried to ream one once for a non-aviation project and it broke into little pieces, so I gather it’s a pretty brittle material.

Interesting, I’ve not seen that wear mechanism on a loose bushing, but sure it’s possible. What I have seen is bushings move in and out and as they loosen from wear, wear accelerates. But you have to go the most conservative response.

Maybe it gets brittle from work hardening?

So he’s saying pull the suction screen how often?

If in fact there were a lateral force the piston pin plugs would gall the cylinder walls because the pin would be displaced laterally?

Edited November 8 by A64Pilot

[Buckeyechuck]

My engine was rebuilt by Penn Yann in 2020. They provide a detailed itemized parts list. Mine includes the affected rod bushings. I’m outside the affected dates but how do you know how long the bushings were in their inventory before being installed. Like ArtVandelay stated above, without serial numbers how do you know?  

[PT20J]

6 minutes ago, Buckeyechuck said:

My engine was rebuilt by Penn Yann in 2020. They provide a detailed itemized parts list. Mine includes the affected rod bushings. I’m outside the affected dates but how do you know how long the bushings were in their inventory before being installed. Like ArtVandelay stated above, without serial numbers how do you know?  

Have you contacted Penn Yan? It’s a Part 145 repair station, so I would think it should have good parts traceability documentation. 

[Buckeyechuck]

Plan on contacting them tomorrow. Wanted to do some research before that as I know they’ve got to be swamped with similar requests. 

[DCarlton]

1 hour ago, Buckeyechuck said:

Plan on contacting them tomorrow. Wanted to do some research before that as I know they’ve got to be swamped with similar requests. 

For what it’s worth, my engine shop said they kept those parts purchase and receipt records for five years.  You might be one of the lucky ones.  

[AndreiC]

10 hours ago, Buckeyechuck said:

Plan on contacting them tomorrow. Wanted to do some research before that as I know they’ve got to be swamped with similar requests. 

As I said in an earlier post, I am also affected, and also with an engine rebuilt by Penn Yan (but in 2012, smack in the middle of the bad period). When I called them they were able to tell me the exact date the bushings were shipped from Lycoming to them. So I suspect they should be able to do the same for you.

[PT20J]

I looked it up and according to FAR 145.219, repair stations are only required to keep records for two years. It might be a good idea to request copies whenever major work is done for your own file. I’m going to do that from now on  

 

[A64Pilot]

3 hours ago, PT20J said:

I looked it up and according to FAR 145.219, repair stations are only required to keep records for two years. It might be a good idea to request copies whenever major work is done for your own file. I’m going to do that from now on  

 

Required and what is done often differs. I stood up the repair station at Thrush and we kept records the same as the factory, forever or in the factories case at least back to 1965 when it opened. Very rarely that information was requested, usually it was used for reissue of a data plate or similar. 

I see it as similar to maintenance records, except for Transponder checks that data is only required to be kept for one year, but anyone who follows that is in for a shock when it comes time to sell.

Personally I’m very much against that rule because it allows an unscrupulous individual to cull negative data and pretend it doesn’t exist, and I’ve even had one of our dealers at the time cut a page out of a logbook of an aircraft he was selling. At the time I thought that illegal, but I guess it’s not, just not ethical.

So in other words I’d call and request a copy of the work order even if it past the date they can destroy it, and I’d offer to pay for their time digging it up and making copies.

Edited November 11 by A64Pilot