Piper wing spar eddy current testing

N

NightSkyReader

Pre-takeoff checklist
Joined
Aug 9, 2021
Messages
104
Display Name
Display name:
NightSkyReader
Thought my PA-28 was no damage history. Recent log scrutiny reveals wing damage repaired 40 years ago (skins, gear strut, and prop). I’m guessing hard landing or runway excursion.
I’m well away from the factored hours limit for mandatory wing spar AD, but my recent research turned up some discussion on the Piper owners forum that implies damaged wings tend to fail eddy current testing more often than non damaged wings, and that maybe damage is more important than hours.
Now I’m seriously considering having the spar inspected, for peace of mind. Does anyone know a good NDT guy who will come to Georgia and do the eddy current test?
 
I suggest you ask your AP/IA whom he has used in the past to get other Piper’s passed. You will need him anyway. The testing company usually does not remove the bolts. Look for somebod who is familiar with the proper removal procedure and does not damage the holes while removing the bolts

If you want the inspection performed in your hangar, consider MobileNDT.com. But be prepared for a hefty travel surcharge.
 
NightSkyReader said:
Now I’m seriously considering having the spar inspected, for peace of mind.
Click to expand...
While dont agree a repaired wing is any more suseptible to failing the test, at one time Piper offered a list of NDT providers for the spar tests. However, there are a number of companies that are familiar with these specific tests so it shouldnt be difficult to locate one close.
Perhaps look on a type club site for options in your area?
 
Bell206 said:
While dont agree a repaired wing is any more suseptible to failing the test…
Click to expand...
What have been your experiences on this matter to have that opinion? I’m trying to learn as much as I can about it before hiring out a NDT guy and would like to know what you know.

I did get a quote from a company who is experienced in the test and will come to my hangar for $2000, but I have to have all the prep work done.
 
It's very important that the person removing the bolts really knows what they are doing. Early in the AD compliance process, there were many stories of bolts being pounded out with brass drifts or just hammered out. The bolt hole needs to be carefully cleaned to avoid a false positive.
 
NightSkyReader said:
What have been your experiences on this matter to have that opinion? I’m trying to learn as much as I can about it before hiring out a NDT guy and would like to know what you know.
Click to expand...
There is a misconception in the Part 91 world that a repaired aircraft is inferior to a non-repaired aircraft. And comments like the one you referenced perpetuate it. Having performed a number of major repairs on airplanes and helicopters the regulatory requirement is the repaired area must meet or in some cases exceed the original factory specs.

Specific to your spar checks the failure rates I’ve seen/heard follow no specific trend other than it appears the right-side forward bolt holes tend to fail 1st.

That said, there is nothing wrong for you to have the inspection performed as a preventative measure. That is basically the core of all inspections to prevent an issue. I’ve probably performed more preventative tasks by a factor of 10 than any other type maintenance tasks.

I believe someone recently posted on PoA a new Piper SB that addresses additional models for the spar check? Perhaps before you commit to the inspection research that new bulletin along with the original spar check SB/AD and see where your aircraft sits.

Then if you want a more factual picture give Piper support a call and ask them about any failure treads they are noting. Part of the SB compliance is to send results (pass or fail) to Piper. But yes there were initially a number of false positives due to various reasons as mentioned above.
 
Bell206 said:
There is a misconception in the Part 91 world that a repaired aircraft is inferior to a non-repaired aircraft. And comments like the one you referenced perpetuate it. Having performed a number of major repairs on airplanes and helicopters the regulatory requirement is the repaired area must meet or in some cases exceed the original factory specs.

Specific to your spar checks the failure rates I’ve seen/heard follow no specific trend other than it appears the right-side forward bolt holes tend to fail 1st.

That said, there is nothing wrong for you to have the inspection performed as a preventative measure. That is basically the core of all inspections to prevent an issue. I’ve probably performed more preventative tasks by a factor of 10 than any other type maintenance tasks.

I believe someone recently posted on PoA a new Piper SB that addresses additional models for the spar check? Perhaps before you commit to the inspection research that new bulletin along with the original spar check SB/AD and see where your aircraft sits.

Then if you want a more factual picture give Piper support a call and ask them about any failure treads they are noting. Part of the SB compliance is to send results (pass or fail) to Piper. But yes there were initially a number of false positives due to various reasons as mentioned above.
Click to expand...
Very insightful. Thank you.
 
Very popular "Bush" planes in Alaska are the PA-32-300 Cherokee Six and PA-32-301 Saratoga. Many Air-Taxis use the Cherokee because of it's impressive useful load per horsepower. The first spars that got inspected failed at a high rate until an experienced Eddy Current NDT person realized that the scratches that were created by removing the bolts was the reason for the failures. Once we started using common rifle bore cleaning and polishing tools the passing rate has been over 90 percent. Most of the Cherokees in Alaska have over 20,000 hours of gross weight operations from unimproved remote strips and pass the inspection with just a good polishing of the holes.

Chances are you will be doing more harm then good removing those bolts. My opinion probably doesn't mean much but, if your spars didn't get manufactured after the Indonesia purchase of Piper you likely don't have much to worry. The aircraft that have had their wings break off are later production from the 1990's thru the early 2000's.

Another thing the A.D. doesn't bring up is that there was scratches in the fuselage from contact with the flap's operation. If your flaps touch the fuselage 'Don't Fly It'.

One more thing... Back in the 70's there was a Cherokee that had both wings break off because the Stabilator attachment failed. Focus on the Stabilator if you want to look for a potential catastrophic issue. Keep those two 1/4 inch bolts, bearings and Stabilator brackets fresh and tight. That's the Cherokee's Achilles Heel.
 
Klaus M said:
My opinion probably doesn't mean much but, if your spars didn't get manufactured after the Indonesia purchase of Piper you likely don't have much to worry. The aircraft that have had their wings break off are later production from the 1990's thru the early 2000's.
Click to expand...
Your opinion means a lot! Do you know what relevance the Indonesia purchase or Piper had to do with weak wing spars? Did they start making those spars overseas during that time using bad materials or standards?
 
NightSkyReader said:
Your opinion means a lot! Do you know what relevance the Indonesia purchase or Piper had to do with weak wing spars? Did they start making those spars overseas during that time using bad materials or standards?
Click to expand...
I called and asked Piper about 15 years ago after receiving parts of low quality. They told me that everything was of the highest standards and FAA approved. Other words, "We're not telling you anything".
 
Klaus M said:
Chances are you will be doing more harm then good removing those bolts. My opinion probably doesn't mean much but, if your spars didn't get manufactured after the Indonesia purchase of Piper you likely don't have much to worry. The aircraft that have had their wings break off are later production from the 1990's thru the early 2000's.
Click to expand...
Two fairly late-model Pipers (an Arrow and a Warrior) had wings come off. Both were flight school planes that had been ridden hard and put away wet. The Arrow had been used almost exclusively for pattern work by low-time pilots and was reported to have been used for aerobatics. The Warrior was flown by a puppy mill, and it’s almost certain that the accident was caused by an improper recovery from a botched aerobatic maneuver.
 
There were three accident aircraft, the ERAU Arrow as you said that is probably the most well known case, and two Archers. One of those spent a lot of time flying pipelines. The other was flown VFR into a thunderstorm so that one doesn’t really count in my opinion but the post crash analysis did show the same kind of spar failure. The other crashes however were both witnessed and the wing just came off in pretty much level flight with no real load being put on the wing.
 
NightSkyReader said:
There were three accident aircraft,
Click to expand...
FYI: Only the ERAU and the pipeline aircraft were due to fatigue failure that I've ever read about. The VFR TS aircraft was a structural overload failure which is a much different failure route and there have been a few over the years. I had posted pics of the spar center frames in another thread somewhere that showed the damage difference between the fatigue failure and the overload failure. If you look in the NTSB docket for the ERAU accident it shows the spar cross-section which indicates the failure mode of the spar. An overload failure will present a completely different cross-section.
 
Meh, this was a ERAU created problem, through and through. I'm so glad I'm out of that moral hazard AD morass even though it cost me a dozen AMUs (sale at a loss). BL, this one isn't OEM malfeasance, this one is 100% owner/operator driven, and we bystanders paid for it. I'd go on what I really think about ERAU, but I'd get banned. Digressing.
 
Last edited:
I should not point my finger at the current ownership of Piper as it changes quite often. The current ownership according to Wikipedia is Brunei Ministry of Finance.

The troubles at Piper started with the bankruptcy in the mid 90's and the 'New Piper Aircraft'. Since then it's been difficult to acquire parts and service is poor.

So today a new A.D. has come out on Pipers that where built after 1994. The A.D. 24-10-04 is an inspection of the wing rear mounting brackets to check that the bolt hole is drilled to the right size. The attach bracket needs replaced if the bolt hole is too big.

Dynamic Regulatory System

drs.faa.gov drs.faa.gov

 
You must log in or register to reply here.
Back
Top