Upcoming AD for many more PA-28 and PA-36 wing spars. 100 anomalies and 6 cracked wings found

Walboy said:
How would one phrase a comment in support of Piper to be effective?
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From my experience, it can be as simple or as complex as you want. Since Piper has taken the lead a simple one line agreement to their letter will suffice. Or your example as well. Its the numbers of people commenting in the same context that matters.
 
The comment period for both ADs ends on 11/7/2024.

So far there are 8 comments on AD-2024-00033-A including Piper's and 9 comments on AD-2024-00008-A.
 
Tarheelpilot said:
Yeah. They don’t give a **** about your ability to afford aviation any more than you care about their retirement.
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I wonder if we should hope they don’t read forums like this and get some idea of how much pilots who haven’t met them apparently despise them; their quite normal human reaction would probably not be to our benefit. Hopefully they’re bigger/better than that…;)
 
Walboy said:
How would one phrase a comment in support of Piper to be effective?

"I am an owner of a Piper aircraft subject to the proposed AD and object to the FAA's proposal. I have read Piper's response to the proposed AD and feel satisfied that their expert analysis and experience with a previous similar AD shows that the proposed AD is not only unnecessary, but potentially more harmful than doing nothing at all."

Or something similar?

I think when it comes to comments from lay persons, the less verbose, the better.
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Try reminding FAA that if the AD causes more failure, they can get sued.
 
How does one go about submitting commentary to the FAA for this particular rule?
 
ArrowFlyer86 said:
How does one go about submitting commentary to the FAA for this particular rule?
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If you go to the links I posted in post #3, at the top of the page is a green button that says "post a public comment".
 
If I were a Piper owner, I would at least send a comment about my local/regional shop rate.

10 minutes of your time divided by the potential market value savings is a LOT of dollars per hour :)
 
I posted a comment. Gist of it was doing the inspections has a risk of damage as noted in the Docket, $85 is way too low for a labor rate and Piper's comment was very fact based and should be considered as part of the final rule making.
 
Llewtrah381 said:
I wonder if we should hope they don’t read forums like this and get some idea of how much pilots who haven’t met them apparently despise them; their quite normal human reaction would probably not be to our benefit. Hopefully they’re bigger/better than that…;)
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I find myself wondering if the FAA and other federal employees have a forum somewhere….probably best to drop that line of thought.
 
ArrowFlyer86 said:
Damn! Piper really came out swinging with their response. To my great surprise - Piper actually seems to be sticking their neck out here to defend the fleet of planes from 50y ago! A lot of gems buried in there.

FAA can't be happy to read lines like:
"[FAA] mis-characterize the extent of collaboration between Piper and the FAA... While it is true that the FAA and Piper worked together to determine an inspection program, the FAA rejected the proposals put forth by Piper. Throughout this process, Piper Aircraft has consistently supported the FAA's efforts while formulating a conservative corrective action plan. The FAA requested extensive data and analysis, and Piper delivered countless pages of comprehensive documentation, most of which appears to have gone unused by the FAA"

I think one of the best points I read in there was their refuting the legitimacy of basing the inspection/spar policy based on 1 single, solitary plane.
"It is not appropriate, nor is it rational to base inspection times on a single airplane which will dictate the inspection program for the entire fleet of aircraft in the field"

I also enjoyed a number of their other points based in fact:
- Sytematically looking at each aircraft that had cracks. Pointing out history of heavy modifications/bad landings/ and in 1 case a hangar having previously collapsed on the plane!
- The same reason they withdrew the AD in the 1980s is valid today (maintenance fatigue + cost). Quote: "On May 22, 1989, theFAA made the justified decision to rescind the AD, citing that performing the inspections could damagethe wing spar bolt holes resulting in premature fatigue and failure of the wing spar, and therefore thesafety benefits did not justify the inspection costs."
- $141/hr is a much more realistic shop rate than the FAA's assumed $85/hr
- Why Group1 has a lower starting CSH than Group2 despite Group2 having higher operational loads/stresses
- That CSH could exceed TIS with the FAA calculation, which results in non-sense answer

It all just sort of makes a case that this proposed rule was assembled haphazardly and without a lot of logic, and definitely not in lockstep agreement with the manufacturer.
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I was also impressed by their described statistical analysis. Some may recall that I did some ad-hoc analysis of this issue a few months back, but based on their reply I am satisfied that Piper worked with the right experts to perform a high-quality analysis of failure rates. That the FAA ignored this analysis and picked numbers based on a single sample doesn't surprise me at all given the sins in the SAIB.
 
Comments Submitted! (to proposed AD, Docket No. FAA-2024-2143)

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. Piper, in its response to comments (to FAA-2024-2142) did a very good job of laying out the background, history and analysis of the spar cracking. Was not aware that this issue arose back in 1987, and the FAA rescinded the proposed AD. It is more than apparent that the aircraft with confirmed spar fatigue cracks were high time, high stress environments. Did chuckle about the one that had a hanger collapse on it.

The prudent pilot part of my brain says.. hey, it is worthwhile to find out now if I do have spar cracks, highly unlikely but the consequence of a cracked spar is pretty much fatal. My analytical brain says… hey wait a minute, aren’t you opening a can of worms executing a relatively complex and expensive process when in all likeyhood the spar is just fine (and you really don’t have to do this). Part of my dilemma involves some of the data in the proposed AD which were very confusing to me. The FAA mentions that they received >2,800 Eddy Current Inspection (ECI) reports, of which >100 reported “Indications”. There is no information on how many of the >100 were resolved or how many actually had spar cracking. The FAA also mentions that Piper later conducted a study of 24 main wing spars of which 20 had ECI “indications” and of those, 3 had fatigue cracks. It is not clear whether the 24 in the Piper study were part of the 2,800 mentioned earlier or were a completely separate group. If it’s the later, that is an extremely high failure rate. If it’s the former, seems as though I have a 1 in 28 chance of getting an “indication” possibly resulting in wing removal for further testing. The proposed AD also mentions that 6 spar cracks were found (as part of the >2800 ECI reports) but it is not clear that an ECI would have found them, possibly they were found when the wings were pulled?

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. Add to that, is the fact (as acknowledged by the FAA) that doing the ECI improperly can cause damage that could led to a formerly sound spar to develop a fatigue crack.

Is there any additional data out there concerning the confidence level or results of the ECI in determining if a spar has fatigue cracks (or the spar is just fine)? I’d be happy to spend some dollars on a test… IF there was a high confidence level that would resolve the issue. The way the Service Bulletin reads (at least to me) is that if I get an “indication” (a 1 in 28 chance? -or- a 20 out of 24 chance?) I get to clean the area and redo the ECI, if the “indication” is still there, looks like I’m pulling a wing to resolve the issue. Some real world experience would be useful.
 
Gary said:
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.
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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.

Gary said:
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.
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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.
 
I cant imagine getting news like this. I gotta get away from certified and finish my kit. Might be some good deals on low-time lycomings soon?
 
I didnt. Is there an example that comes to mind?
 
That makes sense for a certified engine or certified engine prop.
 
moparrob66 said:
I didnt. Is there an example that comes to mind?
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Here are a couple examples straight from AC 39-7. Whether an AD applies to a TC'd or non-TC'd product or article will depend on how the AD Applicability Statement is written. And to add, each AD is technically a new Part 39 regulation and applies to any item covered under Title 14 CFR.

1729273618863.png
 
I now own a Mooney but I owned a PA28-140 for 14 years. These are a good family of airplanes, and a good platform for Piper.

The Wing Spar AD is a big deal here and, even though it is early days still, this is a problem that is going to have to be addressed both for the owners and for Piper. If I were the president of Piper I would seriously consider a remanufactuing/exchange program. I do not make this suggestion lightly.

1. A remanufactured wing would be a relatively quick install in the field, allowing local AIs to upgrade airframes with like new complete wings in just 2 days.

2. There are lots of old relic PA28s around to seed the program for rebuildable cores to get the program started. I know of 3 PA28s around my area at different airports that could provide donor wings to such a program.

3. Piper could rebuild these wings with new, modified, or certified good used spars at a quality controlled facility, streamlining the process making it a cost effective venture for owners of these aircraft.

I realize this is a complicated issue and this may be an oversimplification of a solution. But it is working every day in the diesel engine world, especially for high use items like water pumps, turbocharger cartridges, cylinder heads, and remanufactured complete engines and transmissions.

It is just a thought.
 
All that assumes there is an actual problem. The data presented so far and in particular the response from Piper, draws that into question.
William Pete Hodges said:
I now own a Mooney but I owned a PA28-140 for 14 years. These are a good family of airplanes, and a good platform for Piper.

The Wing Spar AD is a big deal here and, even though it is early days still, this is a problem that is going to have to be addressed both for the owners and for Piper. If I were the president of Piper I would seriously consider a remanufactuing/exchange program. I do not make this suggestion lightly.

1. A remanufactured wing would be a relatively quick install in the field, allowing local AIs to upgrade airframes with like new complete wings in just 2 days.

2. There are lots of old relic PA28s around to seed the program for rebuildable cores to get the program started. I know of 3 PA28s around my area at different airports that could provide donor wings to such a program.

3. Piper could rebuild these wings with new, modified, or certified good used spars at a quality controlled facility, streamlining the process making it a cost effective venture for owners of these aircraft.

I realize this is a complicated issue and this may be an oversimplification of a solution. But it is working every day in the diesel engine world, especially for high use items like water pumps, turbocharger cartridges, cylinder heads, and remanufactured complete engines and transmissions.

It is just a thought.
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Hang 4 said:
All that assumes there is an actual problem. The data presented so far and in particular the response from Piper, draws that into question.
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xenadu said:
The larger issue is I have a strong suspicion this AD will continue to expand over time. They only looked at 2800 airframes in the prior interim AD and found 3.6% with "anomalies" and 0.2% with what I would consider "imminent risk of failure".
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I agree it is early days, and the number of problems found so far do not yet merit such a program. I also agree that Piper may be correct that the FAA is taking too hard of a position on this. It is a gray area as to what to do about it. Only time will tell if this is just a minor analomy or a growing problem.
 
Bell206 said:
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.


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.
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Appreciate the comments, always nice to have another viewpoint! Sounds like I'll be doing some learning on Eddy Current Inspections and the vendors that do them!
 
There's not many people who have written a public comment on the AD, only 21 so far that I can see... :(
 
William Pete Hodges said:
I now own a Mooney but I owned a PA28-140 for 14 years. These are a good family of airplanes, and a good platform for Piper.

The Wing Spar AD is a big deal here and, even though it is early days still, this is a problem that is going to have to be addressed both for the owners and for Piper. If I were the president of Piper I would seriously consider a remanufactuing/exchange program. I do not make this suggestion lightly.

1. A remanufactured wing would be a relatively quick install in the field, allowing local AIs to upgrade airframes with like new complete wings in just 2 days.

2. There are lots of old relic PA28s around to seed the program for rebuildable cores to get the program started. I know of 3 PA28s around my area at different airports that could provide donor wings to such a program.

3. Piper could rebuild these wings with new, modified, or certified good used spars at a quality controlled facility, streamlining the process making it a cost effective venture for owners of these aircraft.

I realize this is a complicated issue and this may be an oversimplification of a solution. But it is working every day in the diesel engine world, especially for high use items like water pumps, turbocharger cartridges, cylinder heads, and remanufactured complete engines and transmissions.

It is just a thought.
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I doubt many Cherokee owners have hundreds of thousands dollars laying around for what a new wing would cost……..that’s why we are flying old Cherokees…………
 
Domenick said:
Piper's response to FAA's NPRM:
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Wow, just wow. There's a ton of work done by Piper to challenge the need for the AD and to argue that compliance has the potential to cause more damage.

It also debunks the machined vs extruded spar as an issue.

Very data driven response that seems to have been ignored by the FAA.
 
mandm said:
I’m wondering what the modified wing spar is, and also why Piper has zero responsibility for resolving this. I mean you made it wrong, accepted that by changing your manufacturing process, and now you want people to buy an overpriced repair kit?
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Not that this is binding outside of a courtroom, but according to Federal Rules of Evidence [407] (and many state counterparts), evidence of subsequent remedial measures are not admissible to prove a defect in a product or its design.
 
2 planes. 2 comments. Thanks for the reminder.
 
Walboy said:
Renewed my AOPA membership based on AOPA's letter supporting Piper's position.

AOPA's Letter
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EAA also provided a comment. I was a little disappointed in AOPA's. They basically just pointed at Piper's, but then Piper's comment is pretty definitive. EAA seemed to put more effort into it. Either way I was glad to see both organizations participating. I was also a little surprised and pleased to see NBAA. Several flight schools including ATP and UND. ERAU conspicuously missing...
 
Jim K said:
EAA also provided a comment. I was a little disappointed in AOPA's. They basically just pointed at Piper's, but then Piper's comment is pretty definitive. EAA seemed to put more effort into it. Either way I was glad to see both organizations participating. I was also a little surprised and pleased to see NBAA. Several flight schools including ATP and UND. ERAU conspicuously missing...
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At first blush I too was disappointed in AOPA's letter. But as you say, Piper's letter is definitive. AOPA doesn't seem to be in a position to write a technical response on their own without expensive outside engineering assistance which would likely conclude the same thing as Piper. I do think it's better for them to put their support behind the most credible authority on the matter and hopefully that carries weight with the deciders in command.

I commented as well, but only to inflate the numbers more than anything.
 
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