Elevator repair advice

[William]

On a slightly sideways landing at Long Mynd yesterday I managed to get a stout twig caught between elevator and fuselage and have bent/creased/cracked the corner of my elevator.

Would it be sufficient to clamp gently and just wick thin cyano into the area (possibly via a small hole drilled in the end edge), or even a small amount of epoxy syringed into it?

Or would I need to use a razor saw to cut into the trailing edge corner, glue in a thin piece of carbon strip then fill with Cataloy putty, sand and paint?

Mikes tailplane repair of carbon strands fed through 2 holes probably wouldn’t work as it’s on the corner.

Any suggestions welcome but I’m hoping to come up with a repair that doesn’t require painting if at all possible.

[oipigface]

If you can set it back in place without clamping, then do it and add some thin cyano. Second best: hold it in place with a finger or two if this can done without putting your finger over the joint. The trouble with clamping is keeping the cyano off the clamp and any shims you use.

[William]

Thanks John, thought of clamping and using wax paper but you’re right: cyano seems to get everywhere and always solidly glues the bits that don’t need gluing ie fingers to elevator

[isoaritfirst]

I think the carbon tows would work. Poke a hole on the front edge and push the carbon in with a small flat screwdriver. 
hold everything flat and wick in the cyano. 
Keep it held at an angle so the cyano stays away from the hinge. 
after a few minutes kick it. 
dint kick it too soon. You want the cyano to wet out all the tows 

[isoaritfirst]

Alternatively. Could you replace the root with a new and possibly thicker piece of balsa. 

[William]

Thanks Mike, I suppose I could open a hole in the side and stuff some tows in with a small screwdriver. Is there any reason to use kicker, it should harden within a few seconds anyway? Will have a look at it again when I’m feeling brave and decide what to do

[isoaritfirst]

Carbon tows are very dry and therefore take a while to dry, which is good. 
only reason to use kicker is because it takes a while dry, and if you think it’s all dry then put it down, you might find that it’s stuck to your bench, or your elevators stuck

[Andy_B]

I'd just get it back into place and put some cyno on it .....if you need to hold it in place after that for 30 seconds or so   put some clear tape over it ........fingers wont get stuck then   and if worse happens you leave the tape on .

Not sure how your going to get any tows in really as its only 1mm thick at that point including both skins 

[William]

Thanks Andy, I agree, I’ve looked at it again and it is very thin at that point. Will try cyano first and if it doesn’t work, try more extreme measures

[Phil.Taylor]

First things first - remove the tail from the fus - then you cant end up with cyano sticking the tail to the fus.

Jiggle the broken piece back into place - then wick thin cyano into the break - one side at a time - with the inboard end pointing downwards. Leave for a few seconds & wipe off any excess downwards. Leave to set for a few mins - repeat on the other side. Leave to set for a couple of hours before putting tail back on fus. Done!

Quicker to do than to type on here!

And - congrats on the 2nd place - that crosswind practice at Whitesheet on Thursday paid off well

Phil.

 

[William]

16 minutes ago, Phil.Taylor said:

that crosswind practice at Whitesheet on Thursday paid off well

 Just what I thought Phil, like Whitesheet there was good lift on one side of the course and treacle on the other!

Thanks for your input - I hadn't actually thought of applying the CA through the crack itself and then wiping away the excess - will try it.

Cheers

[Andy_B]

15 minutes ago, William said:

 Just what I thought Phil, like Whitesheet there was good lift on one side of the course and treacle on the other!

Thanks for your input - I hadn't actually thought of applying the CA through the crack itself and then wiping away the excess - will try it.

Cheers

I wouldnt say lift on one side and none on the other, the side you would say had no lift was where it actually was , BUT it was a downwind turn so it appears theres no lift 

[William]

Mmm... Good point Andy - I suppose a cross wind component will give that visual effect on any slope.

So much to learn

[satinet]

I think if were me I would treat it like wing tip repair. I.e the common situation where a few mm of the tip gets knocked off.

Cut the area off. Use a razor saw to cut a slot. Glue in a piece of flat material (e.g from a servo cover). Fill with isopon then shape. Finally paint. 

[isoaritfirst]

And that’s the fun in repairing things. 
lots of ways of fixing stuff. None right or wrong just a little bit of what you fancy. 
 

I did repair a broken tailplane in a similar break point to that. Although it was the outer part of where the elevator had been cut out. Very weak spot. I managed to poke tows in.  Pushing them in dry is easy, if they go in carry on if they don’t it’s no problem. It’s not like you are smearing epoxy all over everything. 
but as Andy says just drizzling with thin cyano will diva decent enough repair in many cases.