Installing the canopy bubble on a Flying Legend Tucano using adhesive only (no bolts or rivets)
Tools and equipment required before you start
3 tubes of General Electric SILPROF light grey sealant
Sealant gun
Rubber/ plastic gloves
An electric/air sander or a hand sanding block as a minimum
Abrasive paper grit sizes 80, 240, 400
Sharp blades for cutting the set sealer
Saw, we used an oscillating air saw the same as a jig saw. An electric Oscillating tool (as show in op 5) is also very good for this job BUT YOU need to check and practice yourself as if you break the bubble molding it is mega expensive and it will be at your cost. Try it on some scrap pieces first as if you produce too much heat the joint welds back together once the saw has passed.
1. You will need a fair bit of space and you will be producing dust and plastic swarf so in the front room is not the best place. Pick a suitable location and use a table or similar. I would recommend 2 people, you and one helper.
2. Frame to be finish painted on the inside and primed on the outside but the area where the bubble is to be glued to must be left in gel coat ie no paint. Cut 2 pieces of wooden baton to push into the frame as cross beams to keep the frame at the correct width while carrying out this process. Measure the fuselage from a datum point at the front and divide the overall length by 3 and mark at the 2 intermediate points. Measure across the width at that point and then cut a piece of wood 10 mm longer and mark as #1 and then the same for #2 (the 2nd one back from the front ). Measure the frame from the same datum and mark #1 and #2 at the same spacing. Spring the frame and put the wood into their relative positions and tape them in.
Do not remove the protective covering except on the skirt were you intend to cut and glue it to the frame until the plane is ready for use.
3. Stand the frame on the table and lay the bubble approximately in position the correct way around.
If you cannot figure this out then get some help before moving beyond this stage.
4. Once you are happy that the bubble is level and you have about 40mm all around to cut off. Remove the protective film locally on the skirt about 20mm beyond the projected cut line. Using masking tape fix the bubble in position by taping across the bubble and the frame on all four sides. Mark the front edge cut line only using thin masking tape so that the tape is above the cut line. Remove the bubble from the frame and stand on the table or slide it forward so that the cuts can be made without damaging the frame.
5. Do some practice cuts in the excess plastic with your chosen cutting tool before you attempt the real thing. Once you are happy cut as close to the line as possible without going over it, your helper should be supporting the bubble.
6. Sand the face with 80 grit to the guide line, remove the guide tape and put the bubble back onto the frame and check the cut you have just done. If it needs a little more sanding do it now until you are happy with it.(You may or may not use a guide tape it depends how far away it is from the desired position).
7. Locate the cut face into the recess as best you can and then fix the bubble to the frame with masking tape and repeat operation 4,5&6 for one of the long sides.
8. Repeat again for the other long side and then the back.
9. Lay it on and have another last check of all face and after any light modifications sand the edge with 240 grit paper rounding the edges slightly.
10. Put the bubble on the frame and put masking tape on the inside of the bubble such that the lower edge is in line with the top edge of the joint. Now roughen up the approximately 25mm face left that bonding mastic will be adhering to with 240 grit paper, remove the masking tape.
11. Roughen up the contact face of the frame with 80 grit.
12. Mark around the frame with a marker a series of dots in the middle of the contact face at approximately 60mm pitch on the 2 short sides and approximately 120 mm pitch on the long sides.
13. Using the adhesive, squirt a small button approx. 5mm diameter and about 8mm high on all of the dots from op # 12.
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| Adhesive buttons in position |
14. Leave for about 2 days but at least until it is solid enough to cut down with a sharp blade. Using a 2 mm thick aluminium sheet with a 6mm hole in it as a guide plate (or just a bit larger than your button of adhesive). Place over button and cut the button off flush with your guide plate.
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| Adhesive buttons begin trimmed |
15. Coat the face prepared in op 10 with the thinnest coating of the adhesive that your can do but such that it is still opaque.
16. Apply the adhesive to the frame face so that it is reasonably even and approximately 3 to 4mm thick ensuring that there is a surplus to squeeze out.
17. INSIDE FACE:-With a helper position the bubble in place and then tape into position 12 inch spacing with 2” wide masking tape. Score inside joint with 20mm plastic hose pipe. Leave for 1.5 days
18. OUTSIDE FACE:- Remove tape holding bubble in position and scrape out excess from the joint between glass and frame using a piece of thin scrap alum alloy sheet bent through 180 deg . see picture at the end.
19. Paint the frame with it final paint finish coat.
20. Once the paint has set, apply sealant into the groove you have gouged in op 18
21. Using a tea spoon, run it around the joint firmly so that a witness mark is shown on both sides of the groove. Ie edge of bubble and edge of frame. DO NOT TRY AND REMOVE EXCESS AT THIS STAGE.
22. Leave for 2 days until set hard and peal of excess with your fingers, definitely no tools.
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| Scoring the sealer with a tea spoon |
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| Tool for scraping out waste sealer operation 18 |
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