Flaps

This blog cover the assembly of the flaps

Overview
Both flaps were supplied assembled with the necessary twist at the factory only requiring triming of the skins and final assembly.

Assembly.
The nose skin is held with a few temporary rivets that were removed allowing trimming of the nose skins to size. Both skins were trimmed using a Ofla knife giving 10 mm from the rivet line as per the factory standard, then all edges were then filed and polished using wet / dry paper before installation.

Note: The factory uses a series of 5/32 dome head rivets to hold the assembly in alignment  these were removed to ensure the nose skin would be flat. This removal makes the initial reassembly difficult so under no circumstance chase drill any holes they will slot.

The nose was then reinstalled using clecos with the first few being difficult due to the twist required in the flap but once the basic alignment was re-established all the others were installed relatively easily.

All work assembly was done on the aircraft using the flap hinges to ensure alignment and just because is was convenient. All rivets used were domes but countersunk rivets were used on the top side of the nose to ensure no possibility of a foul with the shroud.

In the blog on the shroud it was mentioned that attention should be paid to the alignment of the shroud lower edge, well this was because this builder failed, though not all that bad it could not be left as it was.

Shroud with new lower edge

To fix the problem a new lower edge was fabricated from 0.5 mm aluminium sheet, match drilled to the rear spar. The aluminium shroud was then trimmed to the back edge of the skin and then match drilled through the new edge and then dimpled for assembly.

Cover Strips

The shroud has to be drilled to pick up tabs on the brackets  that support the top skin that covers the flap. They have a habit of bending and the aluminium on the shroud is very soft and will tear easily. To make the forming easier it was decided to add a curved strip to align the skin of the shroud. 

A strip 25 mm wide was formed from 1.0 mm aluminium and fixed to the tabs with structural double sided tape.

The next problem was drilling the holes, these will tear due to the softness of the aluminium used, so it was decided to use a series of small jigs to drill the holes and were fabricated from scrap 2024-T3.

With the location of the tabs marked the jigs were held in position and the holes drilled, once done a cleco was added. The addition of the curved strips assisted maintaining/creating a smooth profile.

The shroud was reinstalled under the folded edge as described earlier but it was noted that the starboard side had small but distinct inflection. It was concluded that this was a result of all the fitting and refitting so the first two rivets holding the cover were removed and to hold the cover straight / flat then two beads of polyurethane adhesive were applied onto the underside of the shroud and reinserted. Finally a length of angle and clamps were fitted to hold the assembly flat / straight while the adhesive dried, it has a long working time and will drie flexible but slowly - like 48 hours.

Note: Doing it again these rivets on the brackets would be removed and replaced by clecos to avoid forcing up the edge.

That's about the lot

Comment
Was the extra work required - not really but at least the builder is happy with the final result.

I left in hope a that all is OK when the clamps are removed, reminds you of that line "Life is like a box of chocolates" - we shall see as there is nowhere to hide.