since 1940

Quick and Easy (and inexpensive) Crack Detection with Dye Penetrate

First the terminology: Dye penetrate uses a visible dye, Florescent penetrate uses a florescent dye that you need a black light to use. Our demonstration uses Dye Penetrate:

Three cans:

• Cleaner/Remover

• Penetrate

• Developer

	Aluminum Test Block this is a test block to various size cracks to judge our ability to detect cracks. We use the cleaner/remover to clean the part
	Spray on the Penetrate This is really awful stuff that stains anything it touches. I recommend you use latex gloves when using it. The stuff seeps under your fingernails and is hard to remove. Let sit for 1 to 30 minutes. You don't need to use very much. Here I sprayed way too much on the sample
	Cleaner/Remover to remove the Penetrate All the penetrate needs to be removed. You can already see penetrate seeping out of two cracks. One at the top on the right hand side and the other at the bottom to the left. Let part dry
	Spray on the Developer Don't breath this stuff - it is like inhaling talcum powder- use a face mask. Also spray on a THIN layer. If you spray too much you mask the smaller cracks. As the developer dries it turns to a white powder. Already you can see cracks on the lower right edge and the two spots I described above.
	Cracks Penetrate seeps out of any cracks. I made a mistake here and turned the block around so the two small cracks on the bottom left above are now on the top left. Larger cracks are quite visible. I probably have too much developer on this sample.

Ok that is how you use the stuff in a nutshell - now for some practical tips and other uses

On a crankcase for example,  if you suspect you have a crack you can clean the suspect area and just spray on the developer. The developer will pull any oil out the crack and you will get a nice crack indication. OK this is not the way you are suppose to use the product but it is quick especially If you are pretty sure that is a crack you are looking at. If you don't get any indication this way you can always go back and use the manufacturer recommended method as the final authority.

Oil Leak Detection. Clean and dry the suspect area, spray a heavy film of developer and let dry. Now run the engine and the developer will contain the oil and show the leak origin

Stain Remover - The cleaner/remover is a high-grade Triclor (dry-cleaning solvent)  and works good at removing lunch stains from your clothes

Penetrate can be used as a "bluing" compound. Spread a little on a valve face and pop the valve onto the seat and you can see the contact area. Works same way on vernatherm contact face also.

It's easy to spray on too much penetrate as I did in this example. What we used to do in the shop is spray the penetrate into a small jar and then use a acid brush or Q tip to dab the penetrate on the part we are checking. It takes far less penetrate and cleaner/remover using this method.

Don't spray on too much developer. Because it goes on clear, one tends to over spray. A light covering is all one needs.

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Disclaimer: sacskyranch.com contains abundant information relating to aircraft maintenance. The information provided  is not intended to supercede or supplement the F.A.A. approved  maintenance and/or operator’s manuals. Those F.A.A. approved manuals must be utilized when performing maintenance and/or operating aircraft.