Monday, April 29, 2013

Stiffener Retrofit Started

You might think that in lieu of official Van's Service Bulletins I am now picking my own side projects just to have an excuse not to finish the project. Well, you might be right but then, this Stiffener Retrofit Kit appears to be a good idea to avoid official Service Bulletin work later down the road. And nothing that is related to the firewall would ever be easy to fix. Not as easy as now, at least.

So, I ordered the Stiffener Kit a few days ago and Van's immediately responded by mailing it. Tonight I took a closer look at it and started.


This should give you an overview of the parts included and the work involved. To inspect the side reinforcements, I removed the tarp on the fuselage and inspected the cockpit area. Not with an easy feeling I may add. I had not looked at the inside since I had reinstalled the rudder pedals after retrofitting their fittings with the appropriate thread sealant. So I was indeed a bit anxious about finding drops of brake fluid on the paper I had put under the pedals back then ....



Without any reason, as it turned out - to my great relief! Everything is at least tight enough to not drop fluid all over the floors. I did not yet do the wipe test with a fresh paper towel but I am a bit more confident to that these days now.
The real reason for this inspection was to take a look at the side reinforcements which will have to get tweaked a bit.

Access does not look tricky (nothing is tricky in there after removing and reinstalling the rudder pedals!). The firewall seal might get damaged a bit, but maybe it will work out ok.

The front of the firewall is a bit more delicate though. The center pop rivet in the following picture, which is partially blocked by the AN3 bolt protruding from below, has to be removed as it will form the end point of the stiffener angle that will get installed there.


The plans also call for the removal of the clamp that guides the cooling hose you see in that picture as well as the removal of the gascolater bowl. I will try to work my way around this as I believe it is possible to pass these obstacles with a longer drill bit and some care.
But first one has to prepare the stiffener angle. As this is a retrofit, we have to attach a spacer on the back of the angle to clear the dimples in the firewall which the newer kits obviously don't have anymore in this area.


The spacer is the part that has the vinyl removed and also shows the cut marks for separation of the part into 4 smaller pieces - after match drilling the #40 holes into the angle. So I clecoed the parts together.


While I was drilling away (clecoing with #40 clecos was not necessary as the #30s held the parts in place), a quail got really annoyingly friendly in the workshop area. So I took a break and inspected what the reason might be for that. I had a hunch and a quick step on the ladder confirmed my suspicion!


Just enough for a quail omelette! If you do not recognize what structure the bird chose for its nest, it is because I am too close. Let me step back a bit and you will see.


I am sure you recognized the stabilator now. The center wrapped up and all dusty hanging under the roof at the workshop. A great and secure place for building a nest if, IF, the bird would not mind my presence so much - which, of course, the bird should have realized before dropping 7 eggs right at the workshop entrance.
Oh well, snakes have to eat too, I guess. The bird would not settle down and accept me working alongside, so I cleared the nest and moved on to the stiffener.

Match-drilling completed, countersinking followed. From the firewall side, I want to add. The idea is to have the spacer riveted on the back so the back is a flat surface that will then sit flat on the firewall and get riveted to it through the #30 holes.


Before I could rivet the parts together, the spacer had to get separated, some material removed and everything had to get deburred.


Don't worry. The parts are unique after the match-drilling and the countersinking, so they will only fit on the angle in the correct way (Van's style, as usual). Before riveting, I decided to prime both sides of the spacer.


Now the parts are drying until tomorrow evening, when I will rivet them to the angle.

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