525's aileron recovering - phots start at the bottom of this page. |
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20 January - so far, between the two of us, we have about 46 man-hours invested in these ailerons. Cost so far is $250 and that includes enough materials to do both ailerons. We have remaining a half-gallon of PolyBrush, one-third gallon of reducer, we used both quarts of PolySpray (silver) and a quart kit of Aerothane white. |
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2 February and the Aerothane goes on. One light coat sprayed first followed immediately by a gloss coat has always worked best with Polyurethane. The Aerothane has a high gloss, but no solids so it runs easily if it's too thick. With the ailerons sitting very level, there's no fear of runs. |
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We turn the ailerons over and spray silver on the other side. It's important to spray the aileron gap seal with silver because, after installation, the sun deteriorates the seal and it splits right in the gap and then it's useless. Dave does the spraying because it's his spray gun. I think he likes to spray paint because he continues to rebuff my idea of him polishing 525. |
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20 January and we spray the second and final coat of Polybrush on the ailerons. |
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First coat on, We'll spray another coat, then turn them over and spray the other side |
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Outside again for the first coat of sprayed-on PolyBrush. |
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19 January - Dave irons out the bubbles, wrinkles and small runs using the small Monokote iron at high heat to flatten the loose pieces and bubbles. The large iron set at 225° is used to flatten the Polybrush runs and sags and smooth the tapes. While Dave is ironing this aileron, I install the gap seal on the other aileron using 3" wide fabric tape. |
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After about 4 hours of cutting, taping and brushing today, they're ready for ironing. |
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The trailing edge gets a 3" wide tape, attached on one side and rolled over the trailing edge in one piece. |
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The sides of the 4" wide tape is smoothed down with Polybrush. |
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The 4" wide piece is laid into wet Polybrush on the front face of the forward spar and smoothed out with more Polybrush. The tape gets thoroughly wetted out and all bubbles, wrinkles and brush bristles are smoothed out and removed. |
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Laying the end piece of pre-shrunk fabric into the fresh Poly brush, it soaks right into the fabric and glues it nicely in place. Important to pre-iron the bends around the corners so the fabric doesn't lift up on the radius of the corner and cause bubbles. |
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Dave applies Polybrush to the areas to be covered by the gussets and tape. |
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All the pieces are measure and cut out; two end pieces and one 4" wide strip for the forward spar with cut-outs for the hinge nodes and the aileron actuator horn. The end pieces are cut from pre-shrunk fabric - just some scraps we shrunk with the iron, before measuring and cutting to fit the ends. |
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One last ironing job over the entire aileron at 350° for the final tightening and it's ready for a coat of Poly-Brush. |
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As stated in the Poly-Fiber manual - every inch must be heated to the proper temperature to assure no loose areas. The exception is that you can't heat up the cemented seams or they'll come un-glued. |
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Iron Man Dave demonstrates his aircraft maintenance skills. |
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After cementing the fabric down on the end-ribs, the ironing begins with a calibrated 250°. Those wrinkles quickly disappear. We'll cut the hinge opening later after some Poly-Brush is on to prevent un-raveling. |
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The top layer of fabric is trimmed off, with plenty of overlap. |
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Smoothing down the fabric seam into the Poly-Tak. The clamps hold the fabric in place using the gravity method while we work the seam. Dave goops the Poly-Tak on while I smooth it down behind him. |
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With one side cemented to the spar, the fabric is wrapped around the trailing edge and draped back over the front spar and is overlapped on top of the first cemented edge. The wide spar of the aileron provides plenty of overlap. Dave takes photos while I smooth out the fabric into the Poly-Tak seam cement. |
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The P-103 fabric is 72" wide, so we roll out a few yards, cut to the length of the aileron, then cut it to the width of the aileron. One piece; wrapped around the trailing edge and glued to the front spar. |
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Right aileron now, almost ready for covering. |
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Next Dave tapes all protrusions and sharp corners with fabric tape. |
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Here's the result of using masking tape over steel screws in aluminum structure. The masking tape holds water that provides a nice electrolyte for some steel/aluminum corrosion. The tape dissolves and leaves this ugly brown mess. Requires another hour of cleaning up. |
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Here's the stuff you need for the Stits PolyFiber process: Iron with temperature calibrations marked, a thermometer for calibrating the iron and thermometer heat sink goop in the white tube. A roll of fabric adhesive tape for covering the sharp corners, numerous rolls of P-103 medium fabric tape in various widths and the big roll of Stits Polyfiber P-103 medium fabric - about 6 yards long by 72" wide should do the trick with plenty left over. A quart can of Poly-Tak adhesive and a gallon of Polybrush orange vinyl goop that stinks like hell and irons down flat to make a very nice and smooth surface. Leftover fabric from 686 on the right side of the photo for end pieces and other places that need small reinforcing shapes. |
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December 2nd and the un-covering begins. I built a couple of holders to facilitate the process - makes it easy. We remove the old covering with a sharp knife - but Dave has to drill out the pop-rivets, that adds an hour to the task. We found no corrosion, cracks or other damage. |
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You can see the water held captive around the rivets by the clear tape - certainly not a good thing! |
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525's ailerons are in pretty good shape, but a few years ago, someone used clear packing tape as a seal - they just laid it on top of the aileron and wing and after a few years in the sun, it's history. (see photo below) The problem is that now it is impossible to remove. That and the age of the covering means it's time for a recover. Easy to do, so I talked Dave into removing them prior to storing 525 at Wurtsboro for the winter. You can see the old tape residue in the photo above. |
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