DAY 116 - 11 DECEMBER 1990 - Phase, NDI, and Christmas Cards
DAY 116 - 11 DECEMBER 1990
Another Airhead.... Then we got started on the Phase on 07, its a Phase B this time. I didn't always keep track of which Phase or which aircraft, but if you consider that we do a Phase every 100 flight hours, you get an idea of how many hours we're flying here. Its just crazy what we're putting these old aircraft through.
Our Phase will be pretty quick this time, as I did about half the zonals prior when I was doing the 28 Day yesterday.
We also have a NDI inspection we do on the NLG strut, there is an area that has shown a tendancy to crack, so we remove the paint there, and do a dye penetrant inspection. This is actually an inspection that I am qualified to do, so I'll give you a quick rundown on how it works. First of all, Dye Penetrant will only find a crack that is exposed to the surface, but it can find a crack that is too small to see.
As I said, we remove all the paint, using paint stripper. Then you thoroughly clean the area with a dry cleaning solvent, and wipe clean with a lint free rag. Then you spray a special dye on the part, and wait a specific length of time (its on the can, the kit comes with lengthy instructions, and it would vary acording to manufacturer, etc). After a minute or so, you take a new clean lint free rag and wipe the excess dye off the surface. Then you spray a white powdery powder on the surface, wait a bit longer, then using a black light, you look for cracks.
Heres what is happening: The dye will seep into a crack, or any grooves. That's why we use chemical paint remover instead of sanding the paint off, the sand paper would leave scratches and they might hide the cracks. Then you wipe off the excess dye, but dye will be left in the cracks. The developer powder will draw the dye out of the cracks and wick it across the surface, making it much wider and therefor easier to see. And finally, under darkened lighting, you turn on your black light, and look for the glowing lines. Its pretty amazing really, because if there is a crack, it glows bright as day, and yet you could look right at it under normal light and usually not see it.
I got some mail today, a can of mixed nuts from my Grandma, a Christmas card from Samantha, over all an alright day, I guess. Breakfast around 0730, and off to bed.
Another Airhead.... Then we got started on the Phase on 07, its a Phase B this time. I didn't always keep track of which Phase or which aircraft, but if you consider that we do a Phase every 100 flight hours, you get an idea of how many hours we're flying here. Its just crazy what we're putting these old aircraft through.
Our Phase will be pretty quick this time, as I did about half the zonals prior when I was doing the 28 Day yesterday.
We also have a NDI inspection we do on the NLG strut, there is an area that has shown a tendancy to crack, so we remove the paint there, and do a dye penetrant inspection. This is actually an inspection that I am qualified to do, so I'll give you a quick rundown on how it works. First of all, Dye Penetrant will only find a crack that is exposed to the surface, but it can find a crack that is too small to see.
As I said, we remove all the paint, using paint stripper. Then you thoroughly clean the area with a dry cleaning solvent, and wipe clean with a lint free rag. Then you spray a special dye on the part, and wait a specific length of time (its on the can, the kit comes with lengthy instructions, and it would vary acording to manufacturer, etc). After a minute or so, you take a new clean lint free rag and wipe the excess dye off the surface. Then you spray a white powdery powder on the surface, wait a bit longer, then using a black light, you look for cracks.
Heres what is happening: The dye will seep into a crack, or any grooves. That's why we use chemical paint remover instead of sanding the paint off, the sand paper would leave scratches and they might hide the cracks. Then you wipe off the excess dye, but dye will be left in the cracks. The developer powder will draw the dye out of the cracks and wick it across the surface, making it much wider and therefor easier to see. And finally, under darkened lighting, you turn on your black light, and look for the glowing lines. Its pretty amazing really, because if there is a crack, it glows bright as day, and yet you could look right at it under normal light and usually not see it.
I got some mail today, a can of mixed nuts from my Grandma, a Christmas card from Samantha, over all an alright day, I guess. Breakfast around 0730, and off to bed.
posted by Carlin at
6:42 PM
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