7.8.2 & 19 Prep bottom skins and flap brace

The instructions are starting to get very brief now and it takes more thinking ahead on my part than simply trusting the plans. A good example of this is the parts that are to be fitted to the rear spar. The instructions simply say “match drill, debur, dimple and rivet x part to the rear spar”. There are three steps where it says the same thing for the Aileron fairing, Aileron hinge brackets and flap brace.

Once I started fitting the parts to the spar it immediately becomes obvious that I shouldn’t blindly follow the instructions.

For example, the flap brace needs to be trimmed to fit. Not only is there no mention of that task in the instructions but the trim marks on the flap brace itself are wrong too. Van’s provide trim marks but if I’d have used those as a guide the end rivet hole would have been way too close to the edge. Instead I offered the part up, marked the trim line and cut. Then repeated until it was just right.

I fitted all the remaining parts and match drilled them. Then I dimpled the Aileron fairings.

That was easy enough but it was clear that I will have to rivet the parts in a very specific order or I could easily catch myself out. I think the final fitting order will be outboard Aileron hinge, Aileron fairing and then inboard hinge bracket and, finally, the flap fairing.

While prepping the flap brace I realised the instructions are simply wrong here. They say to dimple this part but I could see that wasn’t right because the flap hinge fits to it later on so it can’t be dimpled. To check I did some research on the internet and I was right to doubt the instructions. The fairing needs to be countersunk, not dimpled, so that means it needs to be match drilled to the bottom skin now. That also means I need to prep the bottom skins now and then match drill.

So after I removed the blue vinyl I deburred the holes and edges of the right inboard skin. Then I scuffed and dimpled the skin. I dimpled the skin to make sure it was a perfect fit. Then I clecod on the skin to the frame and flap brace.

Bah! The right inboard skin doesn’t cover the entire flap brace which means I’ll have to do the outboard skin as well! Grrr!

I made a start on the left inboard skin but only got half way through prepping it before it was time for dinner so I will finish it next time.

Overall a good few sessions in the shop and an important lesson learned. The instructions are more of a rough guide now. It’s up to me to think ahead and plan properly. I like that.

Fitted pitot controller and Autopilot servo

I’ve had all this bits for the pitot and autopilot servo out on the workbench for a few weeks now. We finished work a bit earlier today so I found myself with a few spare hours and I couldn’t resist fitting the parts to the wing.

The wing has a series of bays. Some of those bays have inspection panels for inspecting the aircraft each year. One of those bays has the Aileron Bellcrank in and some people put their AoA/pitot controller there too. I decided to put mine in the next bay along. However, there is no access panel in that bay so it would be impossible to get a screwdriver in there in the future. So I decided to fit some nut plates to the pitot/AoA controller so that I could screw the controller from the access bay and remove it in future if need be. Nothing complicated, drilled nutplates, riveted nutplates and fitted to the rib.

Next I fitted the Garmin GSA 28 autopilot servo to the right wing. This was like a classic mechano set, lots of metal parts, some nuts, bolts and washers. After a bit of head scratching I got it all fitted.

I had quite a lot of difficulty fitting the brass bushing inside the white bellcrank. The first thing I noticed is that one of the bolts was bowed. Luckily, I had a spare so I replace that. Then I noticed that the brass bushing was fouling inside the bellcrank. A bit of sandpaper wrapped around a brill bit fixed that too!

I know I will need to dismantle the main arm between the autopilot servo and the bellcrank but at least all the parts are off the workbench and safe for the time being.

Not many pictures today’s but that was still nearly 3 hours (fun) work!

Preparing the pitot mast

The Garmin AoA is pre drilled and pre tapped. However, the mounting mast isn’t drilled so I need to drill it. The problem is that the AoA fits inside the mount so there is no way for me to know where to drill while the AoA is in the mount. Here is a picture of the pitot in place, where are the holes?

Surprise, their right here…

This calls for some engineering! I found the thinnest aluminium sheet I could find and cut two strips. I drilled them and shaped them then riveted them together to make hole finder tool.

I dimpled the end of the tool and loosly placed a small rivet in the hole to make sure the tool would lock into the screw holes of the AoA while I drilled.

Once lined up I carefully drilled the hole with a number 40 bit and the enlarged it il to a no 27 hole for an AN507-6R6 countersunk screw.

Once that was done I repeated the process for the other holes and countersunk the new holes so the screws would sit flush.

Two hours work but the results are fab. I’m very pleased.

7.8.15 Riveted top skins

There are at least two ways to rivet the top skins onto the wing. The first is to have a person on the rivet gun and another on the bucking bar. This method has the gun on the outside of the skin. It’s the usual method but you do need two people that are fairly well experienced at both tasks.

The other method is to back rivet the rivets from the inside. Basically someone simply holds a big metal bar over the rivet head while the person on the gun does the riveting work. This method also produces better results with less bad rivets, apparently.

So for those reasons I decided to try and find a 12″ long offset back rivet set. After a good search around it seemed impossible to find one for sale here in the uk. I decided to message my friend Richard and ask if he had one by chance. Luckily he did and was happy to loan it to me! Yay!

Now that I had the back rivet set I was ready to make a start. Luckily my Dad had some spare time and was keen to help. So he popped over and we made a start. The wing skins use 4 different size rivets so first we made sure we knew exactly which ones went where.

Once we were confident about which rivets went were we made a start. Dad was on the outside with a large heavy bucking bar and the cleco pliers.

And I was on the inside with the rivet gun.

We then went on to shoot approximately 1020 rivets to finish the top skins of both the left and right wings. The last bit of riveting was the bottom row of rivets which needed to be done using a hand squeezer.

The wings look great floating in the frame without any clecos holding them together.

After that we also fitted the conduit for the wiring. The first four ribs where a nightmare because they were so close together but the rest were easy enough.

After Dad left I couldn’t help myself and installed the plumbing for the AoA and Pitot.

I got my Garmin GAP 26 down and started prepping it too. There is a problem as you can see in the picture: the silver AoA is predrilled with tapped screw holes but the blue mast isn’t drilled! Hmm, how am I going to fix that I wonder?!

Finally, I fitted the Aileron hinges and fairing I’d prepped the other day for final drilling. It’s getting late so I’ll do the actual drilling next time.

That’s it for this session. One of the most productive weeks so far and I’m super excited to crack on with some fun parts coming up next time.

7.8.8 & 21 Cleco top skins and prep aileron gap fairing

It was supposed to be a day spent Xmas shopping. The weather, however, had other ideas!

Once we got bored of the snow everyone settled in for a day of chilling which, of course, for an RV builder means time in the workshop.

I was hoping the snow would stop and we could resume our original plans so I started with something small. I found the aileron gap fairings and scuffed and deburred them.

Once that was done the snow showed no signs of easing off so I considered finding all the parts for the ailerons and making a start on those. Problem was I had no room on the workbenches so I decided to mount them on the wing ready for riveting. I started by joint compounding all mating surfaces of the wing walk doubler to ribs.

I then fitted the wing walk doublers and cleco’d them from the inside out so they wouldn’t get in the way of the skin that sits on top.

The snow was still falling hard so I covered the wing walk doublers with JC5A compound and then did the same with the next 4 ribs to take the inboard skin.

I had a break for lunch but still the snow came down hard so I carried on. This time with the outboard skins.

That’s all 4 skins fitted and ready to rivet on permanently. Once fitted I decided to check the wing twist just in case there had been any major movement since I put the spar on the frame. The right wing Inboard measured 2 23/32″…

The outboard end measured 2 25/32″.

That’s just a 1/16″ difference between the inboard and outboard ends. Not bad at all. I did the same on the left wing which had a difference of 3/32″ which is fine too. I’m sure these will disappear once the skin is actually riveted in place.

Now that the leading edge, fuel tank and top skins are all in place it was time to remove the support jacks. Goodbye jack!

After 4.5 unexpected hours in the workshop I’ve had enough for one day! It’s still snowing by the way!

7.8.2 Priming top wing skins

I was desperate to get the top wing skins primed but it was far too cold, windy and occassionally snowy outside to prime anything. I came up with the idea of clearing out the old coal shed and using that as a temporary spray booth. I’d done some priming in here before but I’d never left parts overnight. The wing skins are so big they cannot be moved while wet so need to be left to dry in the shed.

Another problem is that there is not enough room to lay out the skins on tables. My dad had a genius idea of mounting some wooding battons on the wall and using 1mm nails to hang the skins. It worked a treat…

Now the skins are sat ready I put a heater in the shed to keep temperatures up to a reasonable level. The next job was to mix some PR30B adhesion primer and suit up.

Once the wash primer was shot we had a coffee break to let it dry and then came back and shot the PR143 sealing primer. No pictures of the actual priming act as it’s not really possible to do given the suit and the work. Once I finished priming I took a picture of the result.

That’s it for the priming phase for these 4 skins. I’ll leave the heater on overnight and let these panels cure in the shed.

7.8.2 Prepping the top wing skins for priming

What follows in this post is a collection of sessions of work. I had a stinking cold this week so I did what I could in between feeling groggy.

The first session involved roping my long suffering better half into holding the inboard skins as I dimpled the skins.

She did a great job and it was fantastic to have some company for a change. She wasn’t best pleased when she spotted this though…

Oops! Lol! A few days later I found my Dad lurking with intent so I roped him in to helping prep the outboard skins.

Again, really great to have some company. Once the dimpling was done on both inboard and outboard skins I was then ready to clean the skins for priming. I’d already scuffed the side to be primed so next it was time to wash off the aluminium residue with Polyfiber 310 Alkaline cleaner and a green scotchbrite pad.

After giving it a good scrub we then hosed it down with tap water and repeated the scrubbing wherever it looked like it needed it.

What’s really interesting is that, after hosing it down, you can see the water being repelled by invisible grease. This next picture has the right side scrubbed but not the left side. It was then hosed. Within a second or two you can see where the water is dispersing from the metal by the hidden grease. Scrubbing it with the cleaner and a green scotchbrite makes the water stick much better.

Once all four top side wing skins had been scrubbed clean I stood them upright in the workshop to dry before painting.

That’s it for now, I just need to wait for these to dry. The workshop is heated and well insulated so it should dry overnight even in the near 0 temperatures we are having this week.

7.8.2 & 8 Scarfed the wing joint corner and prepped inboard skins for priming

Working my way through the instructions and the next step is to chamfer the corner of both skins. This needs to be done because where the two skins overlap leaves them proud of the fuel tank. Because of the air flow direction this is a problem. Where the skins overlap they both need to be filed so they overlap nicely.

It was a fairly easy task. I masked off about 3″ in either direction of the corner and the filed the corner with the files until the corners where scarfed nicely. Once the skins where back on the wing they were no longer proud of the fuel tank.

Next it was time to prep the inboard skins for priming and final fitting. The first task was to sand off the guillotine cut marks using the orbital sander.

Next I rounded the edges of the skin using a piece of wood and sandpaper as a sanding block.

Next I deburred each of the holes on both sides of the skin using the debur tool.

Finally I scuffed the skin all over to give the primer a proper base to stick to.

Once the left skin was done I repeated the process all over again for the right skin! Such fun!

7.7.58 Leak test left tank (again), rivet spar & deblue skins

The sealant in the left fuel tank has been curing since Friday so I started this evening by testing the tank. As previously I connected the manometer and inflated the tank to 1 PSI. At first the pressure seemed to drop a bit but then settled down. Once settled I left the fuel tank on test while I did a few other tasks.

The first task I did was to rivet the holes on the spar between the nut plates. These holes are covered by the fuel tank once it’s fitted but for some reason there are no instructions on what to do with these holes.

I didn’t like the idea of not having these riveted so I went ahead and riveted them to the spar.

Doing the outer ribs was easy but the four ribs at the root of the wing were a lot more difficult. The squeezer yoke just wouldn’t fit in the gap with the clamps in the way. After a bit of head scratching I managed to find a way of holding the flange in place while I riveting the main rivet.

I was pleased with the result. All the rivets are in which should add more support to those ribs.

Next I made a start on removing the blue vinyl from the rest of the wing skins. Again I used the same technique as last time with the wooden pole to role the vinyl off.

While removing the vinyl I was disappointed to find some corrosion in various places. The worst of which was on the wing walk doubler skin.

Although irritating it’s not a major problem. I’ll just sand it off before priming but it does mean that I will remove the blue vinyl as soon as I receive parts from Van’s in future.

Once that was done I returned to the pressure in the left tank which seemed fairly stable. I’ll leave it overnight and check it tomorrow.

7.1.8 Torque tie down brackets to 25″ lbs.

In the last of today three sessions I thought I would replace the short bolt that I spotted. I have no idea why it was short or how it got muddled up but it was an easy swap. While I was at it I checked the torque of all the tie down bracket nuts on both wings and marked them so it’s easy to see if they move in future.

Copyright G-RVAA Official Site 2018
Shale theme by Siteturner
%d bloggers like this: