Sunday, 18 May 2008

Renovation of the Starboard Aileron

Well into May now and my shipment of hardware is only just being shipped from America mainly due to some bulky items including the new windscreen having to be back ordered. In the mean time I have sourced the etch prime and epoxy primer from Trimite in the UK so I can start to strip one of the ailerons and prep all the aluminium components so that when the American shipment is received I can put the aileron back together.

I started by taking numerous photographs of the aileron and all it's fittings and fixtures as a reference for when I have to reassemble the aileron. I will also use the other aileron as a pattern and the wing as a jig for aligning the brackets. Next, I removed the brackets and put them to one side. Because they are visible they will be painted in the red top coat which I don't have yet so I will bead blast and paint these at a later date.

The aluminium leading edge was carefully teased off and the nails removed with with a nail claw. I used a piece of aluminium sheet to protect the spar from being crushed during this delicate operation. Interestingly the aluminium was stamped as 016" 24S-T which according to a colleague of mine, was last used as a standard in
1929. The equivalent today is 2024T3.

The ribs are nailed to the spar so again each rib is teased off and the nails removed. As the ribs are removed they are stamped with a number (starting with the inboard rib) so that they will be reassembled in the same order.

With all the metal work removed from the spar, the plywood patches used to prevent the spar from splitting where the brackets are bolted through the spar, are removed. Although these were glued to the spar they came away very easily. The spar has been crushed by the bracket attachment bolts and will be repaired later.

The only visible damage to the aileron is a small split at the inboard end which will have no effect on the structural strength of the spar.

The spar is then rubbed down with wire wool to remove the old varnish. New plywood patches will be glued onto the spar where it has been crushed. The patches will then be sanded down flush with the spar thus filling the crushed areas. New plywood patches will then be glued on to prevent the spar wood splitting when the brackets are attached.

Most of the ribs needed to be stripped of old paint. This could be done by rubbing down with scotchbright or another soft non-ferrous material but I decided to do this chemically instead to save time. I'm using a paint stripper formulated specifically for removing epoxy and polyurethane paints (D23V). It came in a 25 ltr drum which I have converted into a dunk tank by removing the top then pouring water onto the surface to create a barrier as the fumes can be toxic. The ribs were then suspended in the stripper overnight.

Next day the ribs were removed from the dunk tank. The old paint literally ran off the aluminium and after washing in clean water the results are very impressive.

After washing the ribs were treated with alacrom (surface treatment) to protect them. The ribs will then be painted with an etch primer and epoxy before reassembly.

I should be receiving the wood ordered for the door and skylight frames and the floorboards soon so that will give me another job to be getting on with. At least I will soon be reassembling instead of just pulling the aircraft apart.

1 comment:

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