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Arts Web Site
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Date: 5-28-2018
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Number of Hours: 8.00
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Manual Reference:
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Brief Description: Priming the horizontal stabilizer parts - part 1
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Another long day prepping and priming the horizontal stabilizer parts. My intention was to prep all of the HS parts and prime them in one big batch. As usual, I severely underestimated the time it took for prepping. I needed to leave myself at least three hours of daylight, so I choose to get those parts primed that would allow me to complete the front and rear spar assemblies.
The parts left to prime are most of the inspar ribs, nose ribs and the two skins. I'll do those next weekend.
My chosen process is physically demanding. Wash with Dawn, water rinse, apply Prekote and abraid with Scotchbrite, then final rinse and dry. I chose this method because Prekote is non-toxic, unlike the so-called "standard" process of etch, alodine then prime. When using the standard process you have to deal with collecting the rinse waste and used product and dispose of it at a hazardous waste disposal facility. I've talked to some builders who have just dumped it into the street or down the drain. This stuff contains chromates so it's not to be taken lightly. I'll be collecting the waste for disposal.
I'm going to experiment with the standard process for the remaining parts. The trade off of dealing with the waste is preferable to the effort necessary with Prekote. The skins are too big for etch and alodine, so I've got to use Prekote on them. It's not so bad with large flat parts like skin though. It's the smaller parts like ribs with features like stiffening beads and lightening holes that take all the time.
I asked our M&P engineers at work about this and was told as long as I get a water-break free surface after etching, it's ready to prime. The key is the water-break free surface. That tells you that all of the oxidization has been removed. Alodine and primer is the belt and suspenders approach to corrosion resistance.
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All the parts of the HS minus the two skins ready for priming.
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Washing and abraiding a spar with Prekote. It's very tiring doing parts prep this way.
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I could only get about half of the parts done today.
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