Pinhole woes

[mdevelden]

I'm calling out for expertise,

My 12m Switchblade, which I may or may not have tomahawked into a guard tower, has a pinhole in the leading edge. This is what i have done so far:
Pumped it up and pinched off the struts, in the morning the LE was limp and the struts were solid.
Pumped it up again and used soap water to locate bubbles, which I found between the second and third struts on the LE where the bridle is sewn into the fabric.
Pulled the LE and broke into the towns kiddy pool, going over every inch of the thing by pumping up and holding under water. I double checked the whole LE and triple checked the area where thought the hole was. All I found was that I should have worn my wetsuit.

Where do i go from here?

Thanks,

matt

[dylan*]

It's possible that you poked a hole where one of the strut hoses connects to the leading edge. Hopefully that didn't happen because it's one of the more difficult repairs. Also check the very ends of the wingtips, this is another common area to get small holes and may not have been immediately visible? if it's a slow leak, especially around the valves, you might have to bend the kite around a bit to get it to dump air fast enough to notice where it's at.

[Puetz]

... man,,,, I feel your pain,,,,, those little bastard pinholes are hard to find some times!

What I think is happening is the pinhole will only leak enough for you to see when its under normal pressure, eg 6 psi. It probably won't show easily when the bladder is out side of the kite because you can only safely put, say 1/2 or 1/4 psi in, which probably won't be enough to see the bubble. The little bubble might only pop out one small bubble every 20 seconds and by then, you've moved on looking else where. If you try to pump the bladder up, to any decent pressure, to speed up the bubbles, outside of the kite, the bladder will burst.

What I've done is exactly what you've done so far but this time, with bladder in the kite of course, lather the LE with dishwashing liquid, watching exactly where the liquid bubbles show up, taking careful note the actual measurements where they show up. Use landmarks to measure the bubbles position i.e. use the closest valve is a good one. Also, take note the pinholes orientation compared to the valve too, for example, it may be 90 degrees around to the front, relative to the valve.

With measurements written down, take the bladder out and mark the bladder so you now have a general area of where to look. Go to pool and pump the bladder, enough that you don't damage it of course and hopefully will still see the air bubbles.

This is the hard bit, the bubble can be super small and very slow to bubble out so watch and wait, be patient not to move on too quickly, of course starting with the area you've marked. Slow and steady is the key. If you suspect that you saw something, not quite sure, stop and stare at the area,,,, and wait for it to happen again. You may have to wait some time, be patient, but when you see the f'ing bubble, keep staring at it and bring the bladder to the surface, grab a pen and circle it while keeping your eye on the bubble the whole time. Your nearly there.

Once you identify it and circled it, double check your mark and put the bladder in the pool again and wait for a new air bubble to show. Hopefully you will see it pop out of your circle. If yes, you found it. If no then circle it again with your pen and now triple check it.

If you see the tiny air bubble again, inside your the circle mark, bingo, dry the thing and patch it.

Yay, your done. Plonk it back in the kite and hopefully you don't find the guard tower again.

I hope this helps.

Cheers,

Robbie

[jeromeL]

if it's a slow leak it will be hard to find unless it's pumped hard. Someone in another thread suggested using the marker technique through kite:
pumping it hard / soap up, wait for bubble then use an ink marker through the leading edge to mark the bladder, I imagine you have to wait a bit for it to dry. Then take bladder out and patch.
Once bladder is out you can't pump it hard else it will blow up so if it's tiny pin hole pressure might not be enough to make soapy bubble?

If you don't want ink on kite then you can always replace bladder.

[rogue_kiteboarder]

A single extra pump of pressure when looking for pinholes can make all the difference. You can pump it up and look all day long and find nothing. One extra stroke on the pump and you find it right away.

Try a little more pressure and forget the kiddie pool. Just use a spray bottle with soapy water and spray it directly onto the suspect area and look for a very small trail of bubbles.

[mdevelden]

Thanks for the advise everybody.
I don't think the leak is in the one pump system as I could see bubbles around where the bridle attaches to the leading edge fabric.
I am going to inflate the bladder in the kite again and get a more accurate picture of the where with soapy water. Then I will pull it apart again and will find the damn hole! Or end up drinking too many beers, depends what I get to first.

[EricSanders]

I went through this last year. I ended up tomahawking the kite into the beach grass. I ended up with 16 pin holes so I rate myself darn near an expert by the 16th patch.
I had figured since I need to get to the bladder to patch it, I may as well pull it. I also could see a bit of sand in the wing tips that I wanted to get out. To get the sand out, I used a REALLY small amount of soap in a quart of water and put it in the bladder. I ran the slug of water back and forth until I had worked the sand and water to the deflate valve. Purging the water out the deflate valve under pressure got the sand to dump with the water.
Anyway, back to the pin holes. I filled the bath tub with water and then worked my way down the bladder, twisting off a foot long portion with air in it at a time and then squeezed it together like an accordion under water. Move over a half foot and do it again. I found all but three pin holes like this the first time. When the kite still got soft overnight, I did it again, but this time used a little bit more pressure. The last three didn't blow bubbles unless I had the compressed bladder enough to get the surface good and taught. It helps to have a second hand available to wiper the blade and mark it with sharpy. Sharpy will stop working if you get water on the tip. You will also need to plug the strut nipples before checking for holes of course.

[foam-n-fibre]

If you did hit something sharp then the air should come through the LE fabric in the same place as the bladder hole. BUT, I went through this last year and when I finally found the leak it was nowhere near where air had been finding its way through the outer fabric and bubbling. Air had probably been travelling in a bladder crease before making it through the outer fabric somewhere else. In the end I got good at pulling and replacing one-pump bladders, and would not spend a long time trying to find a leak through the LE fabric, although it's certainly worth trying first, but move on to the next step if it does not work out easily.

Peter

[FLandOBX]

.....Air had probably been traveling in a bladder crease before making it through the outer fabric somewhere else....... In the end I ....... would not spend a long time trying to find a leak through the LE fabric.........Peter

This is good advice, Peter. Trying to find a pinhole bladder leak through the LE, without pulling the bladder out, is usually wasted time. As you say, air can travel within the LE fabric quite a distance from the puncture before bubbling out of the LE at a point of low resistance (e.g., around the stitching where a bridle line attaches - stitching there gets loosened, of course, as the kite flies, so it will be a favorite exit spot for those pesky air bubbles wandering around inside your LE).

Just pull the bladder out, inflate it taut, and submerge (I use a pool or lake) - circle the pinhole with your permanent marker when it bubbles. If you can't find the pinhole with that technique, have you made certain that your inflate/deflate valve is sealing? The Switchblade has a gasket ring on the inflate valve cap - they fall off easily and your kite can have a slow leak there if the gasket isn't in place.

Good luck with it!

[PullStrings]

All pinholes can be found with LE bladder out. Close all the one pump nozzles with small corks you find at hardware stores or other method.
Go pump your bladder on clean grass area (look for sharp debris / sand spurs etc.) near a garden hose.
Pump it not too much. Just a bit over the size of the LE casing of your kite (about 15% more).

Make sure the spraying gun is off the hose. Run the water at very low flow to create a thin sheet of water as you run it slowly over the bladder.
The central part of the bladder will have the most PSI and the tips the least to find the pinholes.

Test first the top of the bladder from tip to tip.
Turn the bladder 1/2 turn and test the bottom from tip to tip.

Have a waterproof marker ready as you run the thin sheet of water and as soon as you see a disturbance in the water flow circle it with marker using dots around leaking spot(s)

That technique will find even the smallest pinholes precisely.

Good luck and patience