Welding Work

During December I begun the preparation of the fuselage for it's eventual bead blasting and painting. There was no repair work necessary as the aircraft has never been crashed and there is no evidence of major corrosion but there are a number of other jobs that need to be completed.

The job list included:

1. Adding structural harness attachment points.


2. Welding on additional tabs to support the baggage sling, 'D' windows, hat shelf, floor boards and skylight.
   
3. Welding up and re drill the rear horizontal stabiliser mounting holes (to be re drilled).
   
4. Have my inspector sign of AD.2008-09-18 (Wing strut attachment bracket).

The plan was that if these jobs could be completed by Christmas, then I would grit blast and paint the fuselage in the period between Christmas and the New Year. Of course things don't always go as planned, but more of that later.

The first problem encountered was that the harness brackets that had been made (http://gbrih.blogspot.com/2009/11/harness-brackets.html) were flawed, the bolt couldn't be fitted because the fabric would interfere, so I had to make new ones to fit (see below). They were manufactured in the same way with the same spec material but now weld at an angle to give better clearance.

My friend David made four post supports from 4130 rod with an internal M6 thread. These were welded to the fuselage to provide additional support for the skylight.

The additional tabs were all welded on over a couple of evenings and I begun to plan the cleaning and painting of the fuselage frame.

The AD inspection was scheduled to be done once the fuselage had been bead blasted as this was purely a one off inspection for corrosion or cracks around the strut attachment fittings and it would mean I wouldn't have to remove paint at a later date.

I'll discuss stripping and repainting the fuselage in the next posting soon.

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.

Removing the Skylight

One of the first jobs tackled was the removal of the skylight as this would give me a little more elbow room while removing the interior. This was a fairly easy exercise but helps to illustrate some of the issues that lead me to wanting to undertake the restoration.

Firstly I removed the tapes that surrounded the edges of the skylight. This revealed the first surprise - the skylight was riveted down in places - to what I'm not sure yet.

I could also see that the skylight appeared to be glued down as well.









Next I removed all the screws that held the skylight to the wood formers around the rear of the skylight and at the front where it overlaps the windscreen. The windscreen and skylight also appear to be glued together.





Using a screwdriver I gently part the skylight from the frame. The glue turns out to be silicone sealant. I definitely won't be using silicone when the skylight goes back in as it's not in the spirit of a vintage airplane.





Separating the windscreen and skylight was more difficult and the windscreen unfortunately succumbed in the process. The Plexiglas at the top had become very brittle probably due to the action of UV light over the years and broke while being separated.
Thankfully, I had made the decision to replace the windscreen after a flight into sun one evening. Although the windscreen looked to be in good condition, it was not good enough to last another 20-25 years so I would have to replace it sooner or later.

This is the resulting mess after the skylight was removed.

The new skylight will be smaller, terminating one bay forward of the existing skylight. This is partly because of the saving in weight but mainly because the additional area serves no useful purpose. It doesn't increase the rearward view at all and in summer helps to create an uncomfortable greenhouse for the pilot and passenger.