Are you in compliance with AD 2024-21-02 (Lycoming engines)?
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John McClanahan
May 27, 2025, 9:56:33 PMMay 27
to FalconRV-List
Hey Group, after a discussion with one of our group members, I thought a note on this could be helpful..
AD 2024-21-02 affects thousands of Lycoming engines. It became effective on 12/5/2024.
If you’re flying behind a Lycoming engine, it’s essential that you’re familiar with this AD. Do you know for sure whether it affects you or not? If not, read on..
This AD requires repetitive inspections for bronze metal particulates during oil changes on many Lycoming engines. But the problem as I see it, is determining whether your engine is affected.
Looking at model numbers, all the common Lycomings are on the list - O-320s, O-360s, O-540s, the injected versions of the same, the IO-390 and on and on. So that’s not much help.
Then we go to part numbers, ship dates and etc per Table 1 which may help or may not depending on whether your engine was purchased new, overhauled, stolen or whatever.
So the way I see it is this -
First, compliance with AD’s is a big deal. Don’t blow it off. If you fly an aircraft that’s not in compliance (as shown in your log book/AD record), you’re in violation of 91.403 and various other regulations. So if something happens and there’s an investigation, you could be in serious trouble. Plus, your insurance may be invalid even if the AD had nothing to do with the issue (requirement to maintain airworthiness).
On the other hand, compliance with this AD is very easy and something most of us probably do anyway (except for the log book part which is probably the most important!).
Ok, so speaking as an IA, this AD seems to break down into three possible scenarios -
1. You’re absolutely sure your engine is not affected.
Action - Update your AD record/log book. State something like this -
“AD 2024-21-02 reviewed. Not applicable per part numbers/ship date (Table1)”. Sign and date - name, certificate held (private, commercial, etc), and certificate number.
2. You think you’re engine is affected -
Action - Comply with the AD - note that in your log book and AD record. Put the writeup in your log book at every oil change and keep your AD record up to date (14 CFR 43.9).
(Compliance only requires that you examine your oil filter (pressure screen if you don’t have a filter) and suction screen for bronze particulates which you should be doing anyway.)
3. You’re not sure if your engine is affected because you’re not sure about what parts are in your engine -
Action - Comply with the AD and put a note in your log book/AD record that states something like this -
“Unable to determine applicability of AD 2024-21-02. Therefore, AD complied with by inspection of oil filter and suction screen per paragraph G, "required actions". No bronze particulates found.”
Put that in your log book at every oil change per 14 CFR 43.9 Sign and date - name, certificate held (private, commercial, etc),and certificate number.
Ok, great. So who can do the required inspection and make the appropriate log entries?
The AD specifically states that the actions required by the AD may be performed by the owner/operator (pilot) who holds at least a private pilot license (so that’s pretty much all of us).
In summary, compliance with AD’s is critical for safety and to keep your pilot license. This is a simple AD to comply with but you must have the appropriate log entries/AD records to prove compliance as required by 91.417.
So make sure your records are in compliance with the AD.
I’ve attached links to the AD and the appropriate Lycoming Mandatory Service Bulletin.
Legal - Note that Manufacturer’s Service Bulletins, even though they may be “Mandatory Bulletins” are not mandatory for part 91 operations (that’s us, and yes, experimental operations are part 91) unless they’re specifically called out in an AD. In this case, SB 480F is referenced as “Guidance” in the AD and not referenced as "required for compliance” unless bronze particulates are found (paragraph (g) (2)). In that case, you must comply with the inspection requirements of SB480F. Therefore, the oil analysis, recommended by Lycoming as “Best Practice” is not mandatory IMO.
Please let me know if you have questions or comments.
John McClanahan
Here’s the AD. The important parts are - “Applicability” and “Required Actions”..
Here’s the Lycoming Bulletin referenced in the AD
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Ralph "Trapper" Trapaga
May 28, 2025, 11:55:48 AMMay 28
to John McClanahan, FalconRV-List
Wow, thanks for all the time and useful information you put into this, John! Good to know...
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JBMcClanahan
May 28, 2025, 6:13:03 PMMay 28
to Dave Romuald, FalconRV-List
Hey Dave - Thanks for the great point about the Experimental Category. In fact, Tommy, Brian, and I were discussing this at lunch today and between the three of us A&Ps/IAs, we couldn't come to agreement.
My point was that part 91 applies to all of us with 91.403 requiring compliance with Part 39 (Airworthiness Directives) with no mention of a carve out for the Experimental Category. Jumping to Part 39, the wording is scary about compliance with ADs, again without reference to Experimental and etc.
So my plan is to research this point in greater depth. When I get somewhere (hopefully) I'll get back to the group with the facts and references.
I received numerous comments so thanks to all who took the time to discuss. I think this is a topic worthy of our consideration and awareness as professional airmen.
Thanks again -
John McClanahan
P.S. Here's a link to 91.403 which contains another link to Part 39.
On Wednesday, May 28, 2025 at 04:05:02 PM EDT, Dave Romuald <dromu...@gmail.com> wrote:
John
Thanks for sharing. I always do an oil analysis and filter inspection as part of my normal oil change.
My question for you is this AD specifically required for experimental aircraft? I did a little browsing on the net and found a blurb that said unless an AD was specifically called out for EAB that it was not mandatory. I scanned the AD but didn’t see an applicability reference for certified and EAB.
Obviously good mx practices would incorporate this and given a known problem we would be foolish not to follow the guidance in the Lyc SB.
But if the AD is not required for EAB then the legal and insurance concerns would not be applicable.
Here’s the Lycoming Bulletin referenced in the AD
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vic syracuse
May 28, 2025, 8:43:59 PMMay 28
to JBMcClanahan, Dave Romuald, FalconRV-List
I would hate to defend it in court trying to explain that AD’s don’t apply to us. Surely you tell your passengers that you are experimenting, right? 🤪
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