12 Apr 2023

Degreased both wing main spars with Plascon GR1 degreaser followed by some Clean Green. Inspected bolts fitted by the factory and confirmed torque seal is in place.

Applied strontium chromate primer to upper and lower spar surfaces along the countersinking plane. After discussion with the factory and determining that the main spars are anodised, I decided that priming the full spar surfaces was unnecessary as there is already a corrosion protection layer; priming was unlikely to get into all the nooks and crannies since the spar is supplied fully constructed and so would likely look unprofessional and not add much value if primered; and it does add a bit of weight and, critically, some additional thickness which may interfere with the tight fit required at the fuselage carry-through spar area which I do not want to compromise. Given that the countersinking does remove the anodised finish in localised areas, and that the top surface is where corrosion could hide underneath wing skins (especially at a skin joint) plus the accessibility to prime it now, it makes sense to prime the upper and lower surfaces only.

Bolted the main spar assembly to the wing twist jigs with 7/16" bolts as suggested in the Sling instructional videos, rather than using the supplied AN bolts. They work really well.

Riveted ribs 1-9 leading edges to the main spar, fitted the 3x AN3 bolts as indicated and torqued to 2.7nm then applied torque seal. Fitted flap torque tube after rib 6 was fitted to ensure accessibility. It rotates very smoothly, I'm very happy with it.

Fitted aileron bellcranks to rib 11 for both left and right wings. Torqued the AN4 bolts to 7.6nm and applied torque seal.

Cleco'd rear spar in place on twist jig and ribs, bolted in place on the jig using supplied hardware.