A new set of aileron hinges

One of the common maintenance issues with Taylorcrafts is th onset of wear in the aileron hinges caused by the hinge rotating against the clevis pin. This is often noticable on the outer hinges and can be checked by pushing the aileron up at the tip; you will feel the movement on the hinge, it's fairly obvious. A small amount of wear is acceptable but as mine are worn to a point where they are only just acceptable I've been on the lookout for a new set of hinges.

Initially I approached the Factory but due to complications regarding the export of stock oversees, and the fact I discovered that I had Rob's jig for the job, I decided that it would be just as easy to make a new set. The jig, in two parts forms the basic shape of the hinge and allows the mounting and pivit holes to be drilled and reemed.





The basic set of six hinges took a weekend to make using the jig and some 0.050" 4130 steel sheet.


1) Six oversize blanks were cut from the sheet steel. The size is sufficient that each piece fits snuggly in the jig ready for pressing.







2) The basic shape is pressed using a vice.









3) While still in the jig, the mounting and pivit holes are drilled and reamed.
















4) The blanks are roughly shaped (original hinge shown for comparrison).







5) Final finishing with file and wet/dry paper and comparrison with an original hinge.







6) The final modification is to spot weld a tab onto the hinge to provide a flat. Each clevis pin will have a flat filed to fit thus preventing the pin from turning against the hinge.

Lastly, my thanks must go to Rob Lees and David Nowill, who between them, designed and manufactored the jig, and then let me use it.

Finishing the Ailerons

I have finally gotten two refurbished ailerons, but before I put them to one side, I wanted to check that everything fits in relation to the wings. I'm basically using the wings as a jig to check the alignment of the ailerons with the new hinges.



The port aileron fits without a hitch but the alignment on the butt rib of the starboard aileron is out for some reason and of course I've no photograph to check the alignment prior to the rebuild.

The extent to which the but rib is out of alignment can be gauged by looking at this photo, about 1 cm at the trailing edge.

To rectify this, I've used a piece of trailing edge, cut down so that it forms a box section that will fit inside the existing trailing edge when it is cut.

After riviting, I will fill the gap with micro balloon filler so that the repair will be less obvious. The rivit heads will be visible because they couldn't be countersunk but tey are no worse than screw heads used all along the trailing edge.

I've checked the fit after the repair which gives a much better fit now with the wing. The ailerons will now be put aside, uncovered, until I come to rig the aircraft way in the future.

Now back to the fuselage and a lot of welding work....

Ailerons and Skylights

Aileron

Just a quick update on the progress of the 2nd aileron. Firstly all the ribs, leading edge, trailing edge and hardware have been cleaned, etch primed and epoxied and are ready for reattaching to the spar. The spar has had some repairework carried out to fix the crushing similar to the first spar. There was also a minor crack running lengthways along the spar from the but, about 6" long and about half the depth of the spar. This will be patched as the majority of the crack lies under a plywood reinforcement plate. The spar had a second coat of varnish at the weekend so I shall be able to start reassembling the aileron next weekend (although I may have to do some gardening as well!).

Skylight

In the mean time, I progress with the skylight woodwork.

Lets refresh our memories of the old skylight. It extended from the windshield back for nearly two bays, held in place by wooden formers and steel angle (see below).

The second bay does not increase the viewable area and just adds to the weight of the aircraft for no advantage; so on the rebuild I will stick to a single piece skylight covering the first bay only.













The frame will be made from the same Ash plank used to make the door frames, using the existing frames as a template. These are rough cut with a band saw then shaped with a spoke shave and finished by sanding. Various notches where cut with a fine chisel.


Some time later after many trial fits, the basic frame sits on the fuselage. Note that instead of using a piece of steel angle on the sides, I'm using 1" thick wood (still much lighter).







My plan is to fix the skylight (3mm clear acrylic sheet) to the frame by embedding a threaded insert (below) into the underside of the frame that I can screw into. In addition I will have four internally threaded steel tubes welded to the cross frame of the fuselage which will suport the skylight and give it some rigidity

I hope to pick up the acrylic sheet next week which will be cut to shape, drilled and used to determine the location of the threaded inserts.





Next week I'll try and update you with the aileron reassembley and possibly a bit more on skylight progress. Untill then happy flying.

First Aileron Complete and a New Hat Shelf

A few photo's of the completed starboard aileron showing the strenghtened but rib.

The tip end rib also had to be replaced as the wood was cracked and had lost much (if not all) of it's residual strength.

Two general pictures showing the end result.

Although I will be starting on the second aileron next week I have also started looking at the design of a map shelf to fit behind the baggage sling. The design (I admit) was taken from that used by Rob in the restoration of G-BREY. Steel tabs will be welded to the fuselage so that the aluminium shelf can be screwed in place with machine screws. The map shelf is large enough that it require stiffening to prevent it from sagging even though it is not intended to support any real weight. It is far enough to the rear of the aircraft that any weight in this area will impact on the c of g of the aircraft.

Next week I'll post more details on the design of the map shelf and the stiffeners to be used.

Completing the first Aileron

By early December the spars have had all the plywood doublers glued in place, drilled for the aileron brackets and varnished with Randolf spar varnish. The ribs are in place but not yet nailed and most other components are primed ready for reassembly.

The first job is to nail the ribs in place. To achieve this I jigged the spar by mounting it onto the workbench with brackets attached with AN3 bolts through the holes drilled for the aileron brackets. I used the old nail holes to locate the position of each rib, and for completeness, screwed the trailing edge to the ribs. I was also able to offer up the leading edge skins to ensure the screw holes still lined up. Once confident that everything is in place, I nailed the ribs to the spar.


Following advice from Rob Lees (G-BREY), I decided to reinforce the butt rib as this has a tendency to bow in with the tension of the fabric when it is applied. A wedge was made from 0.020" 2024T3 aluminium which would fit inside the rib preventing it from warping. The wedge was riveted in place with blind rivets as I couldn't get a bucking bar in the space available if I was to use solid aluminium rivets. The three pictures below show the assembly of the wedge.










The aileron is made up mainly from aluminium parts except for the tip bow which is a 1/2" 4130 steel tube bent to shape and all screws which are stainless steel. Because there is the possibility of dissimilar metal corrosion where steel and aluminium come into contact (even though all parts are primed) I used Duralac, either painted on using a brush or as a dip with the screws which will act as an additional barrier preventing corrosion. The Duralac was wiped off after assembly to keep the structure clean.










The inside of the 4130 steel tip bow was treated with Lanolin (oil) to protect it from moisture which will also cause corrosion. Lanolin is the traditional British treatment whereas America tends to use Linseed oil instead. The downside to Linseed is that it is flamable which can be a problem if a weld repair is required at a later date.









Finally, the leading edges were screwed into place using the old screw holes. Oversize nails were used to secure theleading edge to the spar and the aileron brackets were bolted on.










The aileron will then be checked against the wing to ensure that the brackes align correctly before the aileron is put into storage. I will cover the aileron along with the rest of the aircraft after the final rigging is complete. This is probably better done without fabric on.

The Starboard Aileron - Part 2

In part 1 of renovating the starboard aileron I covered the disassembly of the aileron. Now I can cover the start of the reassembly.

Over the summer, progress was slow as I was waiting for delivery of much of the materials required for the restoration from the US. This took longer than I had originally anticipated (my advice to anyone restoring an aircraft would be to order at the earliest possible date, preferably before you start the restoration as long as you have a good idea of what will be needed). Now that everything is here I can start work again on the aileron.

The first job is to repair the crushing on the spars caused by over tightened bolts that hold the aileron hinge brackets on. You can see in this photograph how the spar has been crushed down around the bolt holes.







The approved repair method is to glue a plywood patch into the recess then sand it down so that it is flush with the spar. This provides a new flat surface on which to glue the plywood doublers for the hinges.

I arranged the plywood so that the visible grain is arranged along the length of the spar.


Simple G-clamps are used to force the plywood into the recess. Aerodux adhesive was used as it is easy to apply with a small paintbrush and any excess can be wiped off with a damp cloth.

Note: you cannot glue the doublers in place yet as this will prevent you from sliding the ribs back on.



All the aluminium parts were etch primed and then sprayed with an epoxy primer to provide a barrier against moisture. I have purchased a 4 stage HVLP turbine with a grvity feed gun for all the spraying. The turbine provides a separate air feed for a half face mask which is a must when spraying with most of the paint systems which can contain some very nasty chemicals. You must ensure that the turbine is located in a clean air source and that wherever you are spraying, the area is well ventilated. For most of the work at the moment I am sparying outside when conditions allow.






All the ribs laid out in order (thanks to them being stamped with a locating number) prior to being slid back on to the spar. I will not nail the ribs on until I have glued the doublers on and revarnished the spar. It all seems very awkward because the ribs have to be on the spar early in the process.




The ribs are slid on in order (and checked against the port aileron which is still assembled).







I then mount the aileron in a make shift jig; two axel stands, which will be used to support the aileron while I put it back together.







I can now begin to glue the plywood doublers back on to the spar. This will take a few days as the glue requires about 24 hours to cure. As each doubler is glued into place I will need to ensure that I drill the bolt holes otherwise I end up with all the doublers in place with no clue to where the holes should be (duh!).

I must say it feels good to see something coming back together at last although there is still a long way to go as I haven't started cleaning up the leading edge or the hinge hardware yet.

Another job looming are the door frames as I have just received some Ash timber so time permitting I should be very busy during september.

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.