I’m a 1967 PA28140 driver with +/-4200 TIS, so I’ve escaped mention in AD 2020-26-16 and the proposed AD Docket No FAA-2024-2142. However, the proposed AD 2024-2143 has me “in the system.” Will be quite a while (probably not in my lifetime) until the Cherokee hits 12,000 TIS, but I do have issues with the facts, logic and justification for the proposed AD. No doubt, fatigue cracks in the spar is a serious issue, but I’m not convinced if this is a big problem or a little problem.
Perhaps some more context between the ADs will help. The only reason for AD-2143 is these applicable aircraft share a common core spar with AD 2020-26-16 or AD-2142 applicable aircraft. There is no direct link, by aircraft model, to the fatigue failures mentioned in those latter ADs. And the common trait of those core spars is a cold-bend manufacture process at the spar mount hole area.
So for your “prudent pilot” part, it may help to address those AD differences than what they may have in common between them. Which is also the same reasons why there are 2 separate ADs and inspection requirements.
For your “analytical” side, perhaps see where you stand as an owner on a scale of “involvement” for lack of a better term. On one side, you have owners that follow only the FAA minimums (Part D annual, ADs, etc.) and on the other end you have owners that follow all FAA and OEM requirements (OEM book annuals, all OEM bulletins, etc.)
So depending where you sit on that scale, it may give you a better overall view at a higher level vs a “tunnel-vision” view on a very public topic. I’ve found that sometimes when you take a step back and see the whole picture it tends to offer a better perspective. Or at least generate more direct questions to your specific situation.
I have zero real world experience with conducting an ECI. Reading through Piper Service Bulletin 1412, the process is not trivial and seems to me, to have pretty low confidence that doing an ECI alone will identify a spar crack, or more importantly, indicate that the spar is fine and can be returned to service.
Eddy current is a proven NDT inspection process that is used throughout the aviation industry on a daily basis. It works. However, as with any inspection process if its not performed correctly, the results may be skewed or invalid. This is no different than performing a visual inspection without a bright light and mirror.
And SB1412 provides the necessary details to perform that inspection down to the requirements to minimize damage during the performance of the inspection. So if you decide to have the spar inspection done, the key with any maintenance is to engage people who know and understand the work at hand and give you the confidence they can perform that work properly in accordance with the applicable guidance. And for reference, this is the same reply I've given people who had asked similar questions on their aircraft for this topic.