My Savannah S model rebuild Blog

[Kyle Communications]

The worst one I have was the first part I did..I wouldnt say its tan in colour but it would be getting close. The rest of the parts are all iridescent gold some a little more than others but generally pretty good. Certainly no powdery looking bits at all. But I am keeping it now a lot lighter in colour. It looks really good too when its done

 

 

[rankamateur]

It looks better than chromate primer but it may not be as durable without a top coat.

 

 

[Kyle Communications]

I would think the alodine has a better resistance as it chemically bonds with the aluminium at the molecular level it would also weigh less. I will still be putting the black stuff between the mating surfaces though. I am going to try brushing on the alodine on the main sheets but only on the inside of them. I will do a test and see how it goes on the new front floor that we made before I get to doing the sheeting. If the brushing scrubs up ok I was even thinking of running a brush line of alodine over all the rivet holes on the rivet lines instead of putting a etch prime over those lines so the rivet head contacts the alodine instead of just the etch primer

 

 

[rankamateur]

What about dipping the rivets to coat under their heads too?

 

 

[Kyle Communications]

You need to acid wash first...I am not sure about if all the acid would come out of the rivet before alodining. Might give it a go and see though

 

 

[rankamateur]

That will cause rust on the rivet stem which may end up discolouring your paint.

 

 

[Kyle Communications]

You wash after acid washing so maybe they need to be put in a bucket of water and agitated to make sure no acid is left

 

 

[bexrbetter]

I just pulled a 20 year wing apart that everything inside is about the same colour as yours inside Mark, it looks like it was made last week, very impressed.

 

 

[Kyle Communications]

I think any future aircraft I make I will do the same for sure. I really like the way it looks and attaches itself to the part and can see why its done. I literally will be pulling every bit of Mabel apart to do all the framing and I am sure I will alodine the inside of all the sheets. I am nearly finished doing all of the frames in the rear then will make a small long tank to do the longerons as well. I am a bit gun shy to acid the wing spar because of how its made and if it wasnt such a big job removing the angle alu on the top and bottom of the spar because of all the solid rivets I would alodining the spar. So I will do it the hard way with scotchbrite then etchprime it. Once I get the back end done then I will pull all the rear cabin and front all apart and do it the same. Up the farm this weekend so no work on Mabel Cut the sheet required to make all new spar to fuselage attachments and the wing strut attachments. I and replacing them because they have had big hits on them. They look fine but just for my peace of mind they are all going to be new.

 

The third last frame I have pulled apart and will make slightly thicker brackets..this hold the tailplane on and always seemed to be a bit light so the tailplane bracket is going from 1.6mm to 2mm thick. I just have to make the 2 brackets and alodine that and then I can do the longerons

 

 

 

 

[spitfire]

Hi Kyle

 

Looks like a very professional rebuild/ restoration, well done to you sir.

 

Mike

 

 

[bexrbetter]

I just pulled a 20 year wing apart that everything inside is about the same colour as yours inside Mark, it looks like it was made last week, very impressed.

Also used a silicone bead along all rivet lines and it's just like brand new inside, 25 years old, not bad going ...

 

 

 

 

 

[Kyle Communications]

Looks like the alodine was brushed on. No corrosion or even dusting by the look of it

 

 

[Marty_d]

What's the wing off, Bex?

 

 

[bexrbetter]

What's the wing off, Bex?

It's origins are complicated, and it's a "Paddy's Axe". Smallish, LSA sized 2 seat high wing otherwise.

 

I'll mention it in my thread at a later date as this is Mark's thread.

 

 

[Head in the clouds]

Looks like the alodine was brushed on. No corrosion or even dusting by the look of it

I don't think that's Alodine. It looks much more like Zinc Chromate primer which was in widespread use for aluminium airframes until a couple of decades ago.

 

ZC lost popularity when it was found to be quite highly carcinogenic. Gloves and positive pressure breathing apparatus should be employed when applying it and treated parts (even old ones) shouldn't be handled without gloves.

 

Edit - there's also a Milspec product that was produced to replace ZC, it looks similar so it might be that.

 

 

[Kyle Communications]

HIC I thought the ZC was a greenish colour?

 

 

[Head in the clouds]

HIC I thought the ZC was a greenish colour?

It comes in green and yellow. The yellow is the colour in the previous images. It should be applied in a very thin coat or it will usually peel off rather than chemically etch and meld with the surface.

 

In the images above the colour is quite typical of yellow ZC when applied with very low viscosity i.e. with plenty of thinners.

 

Not saying it's definitely not Alodine but 25 years ago I think a lot more people were using ZC than Alodine. You can still buy ZC from trade suppliers, because it's probably still the best anti-corrosion treatment for aly but they've made it less readily available to Joe Public because of the health concerns. I think it's mainly the lead, chromium and aromatics that are the carcinogens so gloves and cartridge filters or positive pressure masks are essential when handling it.

 

Google "Zinc Chromate MSDS" and there will be plenty of links to both of the colours and their relative toxicities.

 

 

[bexrbetter]

The builder just told me it's Z C, and the last time he ever used it.

 

He now uses alodine and grey etch primer.

 

 

[Head in the clouds]

The builder just told me it's Z C ...

Then it's recommended to avoid touching it unless you're wearing disposable gloves ...

 

 

[Head in the clouds]

The builder just told me it's Z C

If you've inadvertently handled the stuff you'd want to scrub up plenty and go onto a high vitamin C and iodine rich diet for a month or two, with bioflavinoids and Rubin A.

 

Alternatively you can lick your fingers and shrug it off, as many have done before ...

 

 

[Kyle Communications]

Hi all

 

Been a while since I posted. I had my left hand carpel tunnel done 3 weeks ago and it has really hindered me doing anything but slowly now its starting to come good. Today I finally had enough strength in my wrist and hand to do some light work so I got a 100mm piece of PVC water pipe and put an end cap on it to seal it. It is 3 mtrs long. This allowed me to fill it full of my acid mix and acid up all the long parts I had around here then I tipped it back into my container and washed the pipe out and filled it with alodine and coated the long parts. So all the longerons , the wing rear trailing edge and the extensions have now all been done. I refitted the longerons and its looking great. I still have the main tailplane fuselage former to clean up and the brackets as well to do but they will be done in the usual container. I made before the operation the main wing attachment brackets for the wing at the root as even though they are 5mm thick I am replacing all of the strength attachment brackets in the wing after the bang that each one had. The main root is made from 2inch x 1/4 inch 6061-T6 angle and I machined off the edge to make a flat plate then faced it both sides down to the correct size of 5mm and also this makes it perfectly parallel. I used a old bracket as a template to drill the holes for the solid rivets and bolts and put them in the CNC and milled off the edges to match the original I just have to finish the rounded ends off. The wing strut brackets and rear wing cabin mounts I have cut on the guillo out of 1/8 plate 6061-T6 and they just need to be shaped and drilled. Danny has been doing those as I cut enough for both aircraft and he wants to replace all his as well.

 

After cleaning and alodining the rest of the brackets for the rear of the fuselage I have to rescue 2 rear ribs from a old wing we have for spares and I just need to alodine them and I can start putting a wing back together on the new wing table I built. I forgot how handy it is having a huge table made just at the right height you can see the trailing edge spars on the table

 

 

 

 

 

 

 

 

 

[mcrowley]

Mark, I just watched a video of Zenith flying the CH701 with a new flap handle that has four positions. I guess imitation is the sincerest form of flattery ;-)))

 

 

[Kyle Communications]

Was it on Youtube?

 

Do you have a link?

 

 

[mcrowley]

Was it on Youtube?Do you have a link?

They don't show it, but talk about it in the first 30 seconds... sounded familiar :-)

 

 

 

[Kyle Communications]

Been busier than a one armed bricklayer in Bagdhad lately also a few bits sliced and diced out of me and havent had much time to work on Mabel. I am working on deskinning the flaperons. I have ordered a set of main spars for the outer sections of both flaperons from Reg and 2 outer section skins..they wont be here until January in his next shipment but I want to get all the ribs out and cleaned up and alodined so it is all ready for when they come. Modified my alodine bath for doing long bits. I was using a single 100mm DWB pvc waterpipe with one end capped but it was a pain filling with acid then doing all that and then emptying and cleaning and filling with alodine then doing that but the system was a bit funky so I changed it to make it easier.

 

I got the other half of the pipe and got a few more end caps. I glued on the endcaps then marked the tube at about 220deg and cut out the tops with a slitting disk...took all of 3 mins . I fitted into one end of each pipe a drain plug. Works a treat. I did a test run today for a mate who wanted this new spondooly vertical antenna he got alodined...no one I know of ever in the ham radio game has ever done it so it will be interesting. Most alu antennas after a couple of years really get crusty and need regular maintenance. I havent got any other long bits ready yet out of the other wing so tested this new system on it.

 

I made a cradle to hold the tubes so they wouldnt rotate and were level. Pictures are showing if first with water to do a leak test to make sure they dont leak and also the drain. The filled one with the acid and the other with the alodine and it is a seamless process and its all done at the same time so really happy with it