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Building Integrity
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Date: 8-3-2019
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Number of Hours: 1.00
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Manual Reference: ch 19
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Brief Description: Rebuilding the wingroot
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So here's what happened. I run a downdraft cooling setup on my ez. This means that the engine has dedicated plenums that handle the high air pressure that comes into the cowling and does not put the high pressure stresses on the cowling itself like we see in Updraft cooling systems. Both have their pros and cons, but with updraft, one benefit is flooding the lower cowling and wingroots with fresh cool air. With downdraft, the lower cowl and wingroots are flooded with hot air. To make matter worse, the radiant heat from the exhaust pipes are superheating the air even more.
One reason I went to the exhaust system i currently have along with the Ceramic coating is to lower those temps inside the cowling and it works great, just a little too late. Over time the original exhaust pipes and hot cowling air got so warm that not only would the roll servo shut down, but the foam cores inside the wing roots began to expand into the engine bay which eventually starting contanting the control system! NOT GOOD. This means that the air inside the wingroot would have had to be at least 170deg.F if not hotter. The Thermotc heat shielding just couldn't keep up with the hot soaking that was happeneing. Well, now that I have solved the issue with the exhaust setup and coating, I now have to deal with the over-expanded foam cores by clearing out the 3 plies of BID at the root, sanding the foam down smooth and level again, then laying up new BID and thermotec shielding. Not a terrible job, but one that is very important and is finally getting done. While I'm at it, I'm also upgrading the root bearings, and hardware for an even tighter, more accurate control system. Good stuff!
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Inboard layup removed
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