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Jul 05, 2017, 04:53 PM
Professional sink locator
Thread OP

Repairing a boom break

Broke my Boom...
So yesterday while flying with Brady and Dick I came in a little Hot and landed a little hard for my Xplorer and broke the boom at about the center point, right at it's weakest point.

I've had difficulty in the past with getting the boom lined up straight and true.

Thought about it overnight and wondered if the TD version and the Electric versions were the same shape. Both were the same length from the wing mounts to the tail, so they had to be very close.
I decided to make a plaster mold of the bottom half of the TD fuse and use it as a jig to align the broken fuse while gluing it back together.

The box is made from a $5 piece of 1" insulation foam from Lowes.
I sanded the ends so the fuse was about half way below the top of the mold. The TD fuse was wrapped with a single layer of cling wrap. The pink section is there to give me working room for the repair. Then sealed the ends with some putty to prevent leaks and poured plaster up to the top of the mold.
30 minutes later the plaster was set and the fuse was released from the mold. Cleaned up the top of the mold with a flat surform and it was ready to go.

The broken boom fit it exactly and the alignment was perfect.
Letting the thin CA fully cure and then I will add the carbon patch and she will be ready to fly again.

After the CA was fully cured I did a light sanding and cleaned it with denatured alcohol.
One narrow layer of 3/4 oz kevlar and one layer of 5 oz carbon, both cut on the bias.
Wrapped it with a layer of peel ply, a layer of paper towel, and wrapped it with stretch tape.
It will stay in the mold overnight.
Latest blog entry: Repairing a boom break
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Jul 10, 2017, 05:23 AM
Sailplane Junkie
Billymac's Avatar
Nicely Done!
I had the same thing happen to me on my Alpina. And FED EX crushers crunched my fuse for a Graphite.

On my Repairs, I made a Carbon fiber sleeve that was epoxied inside the boom, and then sanded/ filled and then painted. Weight gain was minor on both and you can't even tell it was ever broken.

I don't have the pictures of my process in the computer that I'm using.

Jul 10, 2017, 11:56 AM
Professional sink locator
Thread OP
Thanks Bill.
The process is so easy that I think I will make a mold of any new plane that I acquire in the future.
Then when the inevitable happens it is real easy to get it back in alignment again.
Latest blog entry: Repairing a boom break
Oct 22, 2020, 10:44 PM
Registered User
mpjf01's Avatar
I've repaired many booms for both myself and others. For alignment I use two lengths of right angle aluminium stock taped on opposite sides of the boom. If my reinforcement is to be on the outside only I just CA the two parts together then take off the aluminium and wrap the break with CF, peel ply etc. If the pushrod tubes are built into the inside of the boom as in a Perfection I use two of the broken rod pieces coated in vaseline in the boom while I use the CA to make sure that the tubes stay aligned and don't get blocked.

If the reinforcement is to be inside only, or as well, its a matter of getting everything in place with the aluminium taped to one end of the boom and then sliding it all together and tapeing before inflating the bladder.

See photo - boom has been repaired already.

I've never had an issue with alignment doing it this way.
Last edited by mpjf01; Oct 22, 2020 at 11:58 PM.

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