PIPER Wing Spar AD - Final Ruling

[Jim K]

Fwiw...
Was talking to the lead mechanic on the field here yesterday. The 141 school's fleet of 10k+ hour archers and arrows have been moving through the shop as time allows getting the inspection done. So far they've done 8 with no failures. He said they started with the ones that have had previous hard landing inspections. He did mention they had a couple that showed an anomaly that went away after cleaning the hole.

The clubs 16,000 hour warrior, used almost exclusively for primary training since being bought new in the 70's, also passed last week.

 

[Kevin Holloway]

Fwiw...
Was talking to the lead mechanic on the field here yesterday. The 141 school's fleet of 10k+ hour archers and arrows have been moving through the shop as time allows getting the inspection done. So far they've done 8 with no failures. He said they started with the ones that have had previous hard landing inspections. He did mention they had a couple that showed an anomaly that went away after cleaning the hole.

The club's 16,000 hour Warrior, used almost exclusively for primary training since being bought new in the 70's, also passed last week.

So, before spending 13-16K per wing, would it be beneficial to pay for a second Eddy Current Inspection if one or both wings fail? The reason I ask; the fight school on the airfield had an EDI on their Warrior, one wing failed, one wing passed, they decided to clean up the holes a little better and got another company to inspect the holes using their approved EDI unit. the second company failed BOTH wings. The Warrior is currently dead in the water awaiting serviceable wings, at probably a cost of over 25K. Question is, how accurate are the EDI units? Could the units be detecting dirt and giving false positives? Would it be beneficial to hire your local, trustworthy mechanic to really clean the holes out or trust an unknown shop with their services before spending a boatload of $$$. Thanks for your experienced inputs!

 

[Bell206]

they decided to clean up the holes a little better and got another company to inspect the holes using their approved EDI unit. the second company failed BOTH wings.

Why doubt the 1st company? Why the need to prep the holes better? And why get a 2nd company? There seems to be something missing from this explanation.

Could the units be detecting dirt and giving false positives?

Normally it does not require excessive surface prep for eddy current. And while false neg/pos are possible as with any test, they are rare and usually are the result of an improper on site calibration step, the wrong standard used, or the positioning of the sensor coil. Considering the certification requirements to perform eddy current this is a serious issue and the 1st company should have been contacted with the last results. Its serious enough that an AD could be issued to double check the 1st companies previous work.

 

[Kevin Holloway]

Why doubt the 1st company? Why the need to prep the holes better? And why get a 2nd company? There seems to be something missing from this explanation.

Normally it does not require excessive surface prep for eddy current. And while false neg/pos are possible as with any test, they are rare and usually are the result of an improper on site calibration step, the wrong standard used, or the positioning of the sensor coil. Considering the certification requirements to perform eddy current this is a serious issue and the 1st company should have been contacted with the last results. Its serious enough that an AD could be issued to double check the 1st companies previous work.

Thanks for the input....I believe the owner wanted a second opinion. He figured it was worth the money to pay for it? but then the second company failed both. One Mech (IA) at the first shop was stating the you need to take a lot of time cleaning out the holes or dirt may cause a hit on the EDI tool. he said he only spent a few minutes on each hole with scotchbrite and a degreaser.

 

[Jim K]

I certainly wouldn't condemn an airplane without at least two independent inspectors failing it, with significant cleaning. I don't know enough about eci to give advice about what's causing the failures or the best way to clean, but on the piper forum there's been several planes that a subsequent testing cleared.

I don't have to worry about this round, but if I did, I'd try to find a shop that does the testing on a regular basis. The shop on my field that does my mx does a lot of eddy current work on jets, and has done a couple dozen pa28s, so the choice would be easy for me.

Why doubt the 1st company? Why the need to prep the holes better? And why get a 2nd company? There seems to be something missing from this explanation.

I'm sure you know a lot more about eci than me, but there's been a bunch of planes that fail on the first test, the holes are cleaned, and then passes the test. Sometimes with the same inspector, sometimes with another. There's something about the holes in the piper spars that seems to be confounding the testing process. I don't know if it's rust or what. At least one person had a burr left over from when it left vero beach 50 years ago.

 

[Bell206]

He figured it was worth the money to pay for it?

Sure. But if the rest of the industry only relies on one NDT test to pass items like crankshafts, etc. there is an issue that needs to be addressed. But only the owners having these multiple tests done are the ones to stop it.

but there's been a bunch of planes that fail on the first test, the holes are cleaned, and then passes the test.

If it is as wide spread as you state then all's that is being done is setting up yourselves to require a second test in the future without some sort of corrective measures. There's a reason a new AD comes out every 10 years on the same old crankshafts: improper testing or surface treating by using improper techniques. I haven't followed this topic but I would be on the horn to Piper as to why multiple tests are required. And getting a Level II or III Eddy Current certification is no walk in the park either requiring 100s of hours of OJT and proficiency tests. It's what kept me from pursuing those NDT ratings. But if it's a process or standard failure then Piper needs to correct that. If its a technician failure, then that opens a different set of issues as most fall under Part 145 rules.

There's something about the holes in the piper spars that seems to be confounding the testing process.

That's what the process standard is suppose to negate. Before each test the equipment requires a check with an appropriate calibration block which is of like material and in some cases form. Maybe a new calibration block is required. I don't know. But to require multiple NDT test of the same component to get an accurate result is far from the norm in my experience.