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BrianL

Tailplane Repair Advice

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BrianL

The tailplane on my Malibu Pro was damaged today when the farmers dog accidentally caught it with one of her claws.  It has left a score in the top surface which in places has cut right through.  It’s also compressed almost through to the bottom surface.

Is there a recognised way to repair this sort of damage.  My priority is to restore the strength, with appearance of secondary concern.  (It’s my first DLG and I’m sure it will get a few knocks while I improve my flying skills)

My suggestion is to run some 30 minute epoxy into the cut and cover with a piece of crystal tape while it is still wet. The epoxy will fill the ‘V’ and the tape will restore some strength to the top surface.

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Phil.Taylor

Yes but..

Lay some carbon tows across the spar as well - will add back some of the lost strength

The crystal tape will add no strength at all in an upwards bending direction

Phil.

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Baldrick

I've had some good results using Paul Naton's method of removing reducing creases in foam surfaces... (he does some really good videos). 

drill a line of holes along the crease, darning needle or 1mm drill 

then lay a wet folded up paper kitchen towel over the crease and use a film iron to turn the water into steam, this heats up the creased foam and the crease nearly all but disappears., 

you can then inject foam safe superglue into the holes and gently rub the top skin down onto the foam and spar (wrap your finger with cling film) try to keep it as clean as poss. 

if the spar is broken it can be repaired  but it will take several steps to complete. but bear in mind every gram you add to the tail will mean you have to extra weight to the nose to balance 

filling the groove with 30 min epoxy would add little strength and a lot of weight to the tail...

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pete beadle

Hi BrianL

I think Baldrick has the right idea, Paul Naton's tip regarding creases in foam usually DOES work very well

I also note BrianL's comment about cosmetic considerations not being foremost  but.....I would insert drops of foam-friendly cyano in the crease at 5mm spacing to stabilise the weak point

Then, to make the repair a bit less obtrusive I would  cover the whole repair with a strip of pink  iron-on film just wide enough to hide the crease.......so, a bit stronger but not much heavier, and cosmetically pleasing too.....win/win:yes::thumbsup:

Regards

Pete

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Baldrick

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BrianL

Best laid plans !!!

Repair completed and tailplane now as strong as before but it didn’t go to plan:

I placed a piece of damp tissue over the score line and warmed it with the tip of a film iron and the steam generated lifted the compressed foam.  It was clear that the glassfibre surface was not cut but was still a little dented.  Unfortunately the heat from the iron over the adjacent tailplane surface lifted the glass fibre off the foam core.  It also seemed to shrink the foam so there is now a slight dent in the surface. This happened in 3 or four places even though the iron was about an inch from the surface.  So this ruled out applying iron on film over the repair.  I used a pink felt tip pen to colour where necessary 

I then found out I was out of foam safe CA

So I mixed a little 30 min epoxy, and used a thin piece of fibreglass tissue over the remains of the score.  I put crystal tape over the joint and left it to cure.

With hindsight I used too much epoxy, but the slightly raised finish is no worse than the heat damaged surface next to it.  As long as you can’t see the light reflecting off the surface it looks ok.  

Finally I checked the COG and it had only moved 1 mm.  There’s already 2g of lead at the back of the fuselage which moved the cog 7mm so the weight I had added was negligible.  I can remove a bit of the lead if necessary.

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pete beadle

Hi BrianL

Well done!:thumbsup:

I doubt whether the fellas you fly with will even notice the repair.....so don't tell 'em OK?:)

BTW How much is a new tailplane these days? Whatever it is, you've just saved that amount:yes:

Regards

Pete

BARCS1702

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BrianL

Thanks Pete

replacement tailplane is £17

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Baldrick

Can’t even see the repair in the last photo,

well done good job!

As Pete says you’ve saved a bit of dosh as well

iron might have been a bit hot...  but now you’ve done it once it will be much easier 2nd, 3rd time round ( voice of experience) 🤓

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