Piper SB 1345 - Wing Spar

PaulR035

PaulR035

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Paul R
Thoughts from other Arrow/PA-28 owners out there? Here are a few things I'm wondering:

  • I thought the FAA was using a factored-time-in-service model to keep the AD from affecting most private owners. Any thoughts about why Piper is just saying flat-out 5000 TT?
  • Obviously the "proposed AD" from last spring affected all PA-28s- why does the SB just affect Arrows when they have the same spar design as the rest of the family?
  • Is it more likely that the FAA will simply adopt SB 1345 *as* the AD? Or is it more likely that the FAA will modify their "proposed AD" (so that we'd see things like FTIS, all PA-28s affected, etc).
  • Have you had the Eddy Current inspection done? What was it like?
 
I am no expert on this and it's news to me that Piper had issued a service bulletin. So I dug up a couple links:
Short article: https://piperowner.org/piper-issues-service-bulletin-on-arrow-main-wing-spar/
Actual SB: https://piperowner.org/wp-content/uploads/2020/04/SB_1345.pdf

My plane has about 1300 hours until this would be due. That makes me kind of happy. I will say that it's good they only require 4 of the wing spar bolts per plane to be removed for inspection. I suspect that that will ease the burden on owners. And making it apply by TTAF rather than a complicated formula is probably a good thing. More planes will require inspection than under the proposed AD, but how many of us have logbooks that say the annual inspection complied with a 100-hour inspection, even though the plane didn't have mandatory 100-hour inspections at that time? Logbook entries like that could have made a mess of calculating whether your plane needs the inspection or not. A straight TTAF figure is much easier to apply in the field.
 
PaulR035 said:
Is it more likely that the FAA will simply adopt SB 1345 *as* the AD? Or is it more likely that the FAA will modify their "proposed AD" (so that we'd see things like FTIS, all PA-28s affected, etc).
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FWIW: from my experience, since Piper has come out with a new SB that addresses the spar fatigue issue from the ERAU accident the FAA will monitor results Piper receives from those who do perform the SB. If results reveal more aircraft with fatigue cracks then probably the AD will be released and will use the SB as compliance. On the other hand, if results show no further fatigue cracking (based on owners performing the SB) then they may not release an AD.
 
That SB is news to me as well, I often wondered about what the heck happened to the AD. Anyway, good to see my plane isn’t listed there
 
My PA28-181 is not part of the SB, and very happy so far. I sent a comment to the FAA about the proposed AD very late, but got feedback that they were still considering what to do and were very sensitive to the issues for so many potential aircraft. The go slow seems appropriate. We’ll see what the SB data reveal going forward on those P28Rs, but keeping my fingers crossed. Also, if eddy current testing is required, this is a far cry from mandatory removal in otherwise normal appearing bolts.
 
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When King Air wings were falling off (prior to about 1982), Beechcraft completely changed how the wing was attached. Changed from tension to shear bolts. Also introduced "Inconel" bolts.

There was also an AD, for a short period of time, where we had to slow the hell down
 
Why is the Arrow wing and not the Archer wing impacted? Aren't the planes nearly identical save for engine and gear?
 
Hang 4 said:
Gear
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what does whether the gear swings up and down or stays down permanently have to do with the spar attachment itself? How does it alter the stress and fatigue cycles? Turbulence, landing force, maneuvering Gs, would all be the same, no?
 
Tantalum said:
what does whether the gear swings up and down or stays down permanently have to do with the spar attachment itself? How does it alter the stress and fatigue cycles? Turbulence, landing force, maneuvering Gs, would all be the same, no?
Click to expand...

This is exactly my question... is this a sign that the powers that be are really just doing a science experiment to find out if there is a fleet wide issue rather than cracking down on a known issue? In other words, I have to imagine that if nothing is really found, maybe no AD. And if something is found, I bet the AD will apply to the whole PA-28 line.
 
PaulR035 said:
This is exactly my question... is this a sign that the powers that be are really just doing a science experiment to find out if there is a fleet wide issue rather than cracking down on a known issue? In other words, I have to imagine that if nothing is really found, maybe no AD. And if something is found, I bet the AD will apply to the whole PA-28 line.
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The only thing I can think of is that the general use case of the Arrow is a little different, that subjects it to more stress, like repeating abusive landing cycles by students practicing power off 180s
 
Even though the Arrow’s gear retracts, is the attachment point to the spar farther outboard than an Archer such that there is greater torque applied to the spar attachment bolts on hard landings?
 
Tantalum said:
what does whether the gear swings up and down or stays down permanently have to do with the spar attachment itself?
Click to expand...
FWIW: While I have very limited experience with Pipers, in general, aircraft with retractable gear tend to have structural "boxes" in which the gear nestles. The extra structure is required for the multiple pivot points of the retract mechanism. Fixed gear, in general, tend to have a single load path to the aircraft primary structure with secondary "bracing." My guess is that with the additional retract structure (multiple load paths) the singular fatigue issue is not as relevant in the Arrow series???
 
MajorTurbulence said:
Even though the Arrow’s gear retracts, is the attachment point to the spar farther outboard than an Archer such that there is greater torque applied to the spar attachment bolts on hard landings?
Click to expand...
PaulR035 said:
Thoughts from other Arrow/PA-28 owners out there? Here are a few things I'm wondering:

  • I thought the FAA was using a factored-time-in-service model to keep the AD from affecting most private owners. Any thoughts about why Piper is just saying flat-out 5000 TT?
  • Obviously the "proposed AD" from last spring affected all PA-28s- why does the SB just affect Arrows when they have the same spar design as the rest of the family?
  • Is it more likely that the FAA will simply adopt SB 1345 *as* the AD? Or is it more likely that the FAA will modify their "proposed AD" (so that we'd see things like FTIS, all PA-28s affected, etc).
  • Have you had the Eddy Current inspection done? What was it like?
Click to expand...
FWIW, I just had it done. Very simple. Only took a day for my A&P shop to schedule the eddy current (they had to outsource to a third party) - thankfully no cracks found. I don't have the bill yet but A&P said it was only a few hours work + eddy current cost - I'm guessing it will be under $1K all in.
 
MJR Pilot said:
FWIW, I just had it done. Very simple. Only took a day for my A&P shop to schedule the eddy current (they had to outsource to a third party) - thankfully no cracks found. I don't have the bill yet but A&P said it was only a few hours work + eddy current cost - I'm guessing it will be under $1K all in.
Click to expand...
How much of the plane had to be removed to get to the bolts in question? I haven't looked at what's involved but it seems that it is probably easiest when the plane is already somewhat disassembled for its annual inspection. But I'm lucky, because my plane has the luxury of lots of time before the SB is actually due.
 
iamtheari said:
How much of the plane had to be removed to get to the bolts in question? I haven't looked at what's involved but it seems that it is probably easiest when the plane is already somewhat disassembled for its annual inspection. But I'm lucky, because my plane has the luxury of lots of time before the SB is actually due.
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I don't know the details as I wasn't present for the inspection, but it was done pretty quickly and A&P told me getting access to the bolts wasn't very challenging. I'd just call your shop and ask their view - most places should have relationships with structural testing firms that can provide the eddy current test and should be able to give you a pretty good estimate.
 
Here’s a Q that I thought of after this thread...

PA28 wing walk weight limit? I’m 160lbs and all of my pax are no more than 220lbs, but what’s the limit? How much weight can the wing support?
 
Ryanb said:
Here’s a Q that I thought of after this thread...

PA28 wing walk weight limit? I’m 160lbs and all of my pax are no more than 220lbs, but what’s the limit? How much weight can the wing support?
Click to expand...

At least 270......
 
Any time you drive the wing bolts out or in your scratching the bore of the holes in the spar causing stress risers. A previous AD pulling wings did more damage then good. I have seen the washers installed digging the sharp edge in the spar causing a stress riser. Most Piper Arrows will show evidence of hard landings with cracks at the base of the swivel joints on the main gear. Sometimes you have to remove it to see it cause it runs vertically along the base. It usually in the reinforcement web only.
 
Ryanb said:
Here’s a Q that I thought of after this thread...

PA28 wing walk weight limit? I’m 160lbs and all of my pax are no more than 220lbs, but what’s the limit? How much weight can the wing support?
Click to expand...
Probably isn't one, realistically.
 
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