Warbird Information Exchange

What kind of work is there in NDT (non-destructive Testing) in the Warbird / Aviation world? I ask because I work for GE and worked with NDT test equipment and inspection of power stations Turbines and Generators. I’m not certified or educated in the field, just some OJT. I’ve often wondered.

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Any engine overhaul shop for general aviation will likely do dye check/Zyglo and magnetic particle inspection. Airline/aerospace shops will do x-ray and sonic/ultrasonic (A-Scan, C-Scan, Sonic Bondmaster, etc.) inspections as well.

As for warbirds, historically I've never seen more than dye-check except in very specific cases where a specialist was called in or the part was sent out.

Aren't those methods of "Non-Destructive Inspection" (not testing)?

The USAF, in addition to dye penetrant and X-ray, also uses eddy current checks to find cracks and fatigue.

Good Morning Gentlemen,

As far as applications for NDT in the Warbird field go, I can only assume that there can be some ot the same "general" types of inspections as there are in Jetliners of today. Boeing, McDonnell Douglas, and Airbus, to name a few ALL have separate volumes of their maintenance manuals dedicated to nothing but NDT practices and procedures for the respective arframes and engine you have in from of you. GE, P&W, Rolls Royce all have their own manuals for these items.

As far as General inspections for Warbird or "Light Aircraft" go, from what I have seen these inspections are carried out by overhaul shops who have some capacity to perform these inspection.

As far as the term "Dye Penatrent" goes, that can refer to two types of "dye". Either the "Red" or the Flouresecent types of penatrant. However, a word of caution would apply here. Most, if not all modern jetliner have taken the use of the "Red" dye completely out of their usage. Mainly due to the following reasons. Red Dye pen, when used is not easily cleaned up as many of you who have used it have found. It gets everywhere. And it has been found NOT to be as sensitive when inspecting for defects as the Flourescent pen. Additionally, due to the fact that the Red Dye doesn't clean up or be as removed easily and completely, it will remain in even the smallest defects and basically act as a barrier or plug to those defects later when Flourescent Pen is used, thereby diminishing the Flourescent Pen's effectiveness in the inspection process. Also, the modern jetliner manufacturers have found that over the life time of the parts being inspected, Red Dye tends to be corrosive to aluminum if not COMPLETELY cleaned off after the inspection process. And we all know how much fun cleaning that Red Dye off is don't we ?

As to the other methods used for modern Jetliner inspection, Eddy Current (E/T), Ultrasonic (U/T), Mag Particle (M/T) for steel and ferromagnetic parts ONLY, and in the instance of say Engine Mounts, X-Ray (R/T). Most all of these inspection techniques require instruentation that is very expensive and pretty serious training for a tech to know what he is doing.

As to the idea that many of these techniques are or can be adapted to Warbird use, I am sure that there are many that can. But consult the service bulletin or AD note BEFORE you attempt to modify any inspection.
If you are wanting to have any of these types of inspection done...I SINCERLY URGE you to contact a REPTUABLE shop or individual before proceeding. The only hazardous one I mentioned is X-Ray.

As I posted in another thread, I am certified in all of these methods (16 yrs) and I am NOT attempting to promote myself, I just wish to help get folks more informed. If there is anything I can help you with...please...shoot me a note.

Paul

Here is a datapoint for the need of training and staying current in the inspection process. Last year the decision was made at Lockheed Fort Worth that to keep a certification in Zyglo inspections, the inspector had to log at least 200 hours of Zyglo inspection time along with a recurrency inspection class and pass the inspection exam. We went from about 40 people carrying the certification to less than 5.

It's not rocket science, but without good training and lots of experience under good inspectors, you can fool yourself and get into trouble real easy.

NDI, NDT, and NDE (evaluation) are used pretty much interchangeably from what I have seen.

Dye penetrant is supposed to be used w/ a blacklight. I tried it on some castings, but couldn't use it. It was too messy, and didn't seem to help much in finding cracks. The castings have a really rough finish, and the dye penetrant just fooled me on the rough surface by showing the texture too much.

does the auto industry use the same safety test technology?? sure wouldn't hurt them, or us for that matter!!!!

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tom d. friedman - hey!!! those fokkers were messerschmitts!! * without ammunition, the usaf would be just another flying club!!! * better to have piece of mind than piece of tail!!

Harvard,

Yes, Zyglo (Flourescent Penetrant) is extremely messy, and the use of a Blacklight is needed to accomplish the inspection. However, as is the case in modern jetliners, these blacklights also need to be checked and verified to assure the user that the light itself is of adequate intesity to be able to see the defects. As is the case of castings, if the surface is excessively rough any penetrant is going to be, at best, a judgement call. Based on the surface conditions of the part in question. Red Dye, as I had attempted to illustrate is not used due to it's inability to be completely removed from the part without the need for severe cleaning methods...IE...vapor degreaser (trichlorethelene) which is almost completely removed from public useage due to environmental issues. The Red Dye will dry while still in the defect and basically act as a plug barrier to future inspections requiring the use of Flourescent Dye's. Cleaning of the parts to be inspected is both a necessity and a requirement. Both in a "pre" cleaning prior to the inspection, and "post" cleaning of the parts.

Eddy Current inspections also will suffer from suface conditions as well. When having anyone perform these inspections, training and currency on the equipment and techniques are extremely important. Along with an individual's experiance level.

Manufacturer's and companies, for the most part, have programs in place to assure the quality and training of the inspectors performing these duties. And they stem from both FAA and MIL-Spec requirements that are in place at the Federal level.

Hope this helps.....if I can help...shoot me a note.

Paul

Yep,

you are correct. NDE, NDT, and NDI are all basically the same thing.

Paul

When in doubt, replace it! You can also smooth the surface a bit by sanding and try again. Do you have a reason to suspect a crack, or were you just experimenting?

bdk

Just experimenting, take it easy.

I'm all about easy!

Hi bdk:

Yes, did you try to dye penetrant your castings? Since you have a Harvard with the rough castings, I suppose you quit right there? Or did you end up x-raying all your castings?

Chris

Just visual inspection. Haven't needed to go any further than that. Nothing questionable has come up to date.