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Saturday, October 08, 2016

Longeron repair

Right side (22.5 hrs)

In this post I am going to complete the longeron repairs by finishing the right one. I’ll mostly dump the photos here and add some comments. For a more thorough explanation of what and why, check out the left longeron repair.

Broken longeron with 3D printed ABS cutting guide nailed to it

Longeron getting cut along the 7:1 cutting jig

A top view of the surgery

Removing the damaged longeron from the fuselage

What it looked like right after the two sawing operations

All cleaned up and ready to get worked on

This fiberglass corner got damaged during the fall, and will need to be replaced.

I started by floxing the part where the foam got removed. I reused the jig to contain the flox.

After a little sanding, I had a flat base for the next operation.

The 3D printed ABS jig was used again (on a table) to cut this longeron splice

2 BID plies at 45ยบ replace the original substrate. Most of this will be eventually cut off to accommodate the CS spar.

Right after peel-ply removal, the next day.

BID trimmed down to size

Getting ready for the longeron splice installation

Once again, flox only was used as a bonding agent.

Flox added to both sides of the splice, and the sidewall.

Careful longeron alignment

Pressure added during the cure

Laying out a plan for the outer fiberglass replacement

Original fiberglass sanded in accordance with the plans' repair section (page 3-22)

First layer of UNI being laid

UNI saturated with epoxy

Second layer of UNI laid with opposite orientation (as per plans)

Second layer wetted with pure epoxy

Additional BID layer to cover the repair

With the surgery completed, this patient needs some rest time to be fully cured.

Peel-ply bandages, and Saran wrap to keep air from infiltrating.

Finished outer repair

Prepping for the "inside job"

BID pre-preg ready to be impregnated

Epoxy mixed with Cab-o-Sil painted over longeron and sidewall. A flox fillet was added in the bottom corner.

Pre-preg applied to the fuselage. All air bubbles were later squeegeed out.

Inner repair after the addition of peel-ply

Peel-ply removed the next day

This longeron repair is done!


  1. Welcome back! You are now in good standing with the canard building community once again! ;)