fuselage damage repair

[jpaul]

I have a series III that has some fuselage damage. A ski hook/dropped into a crack in the ice, bounced out before coming to a complete stop. I am looking for suggestions on how to go about repairing the damage.

[n85ae]

Strip the fabric, then probably cut splice and weld in new sections of tubing.
Probably the covering, and painting will be the worst part.

Just a guess.

Regards,
Jeff

[HighWing]

I agree with Jeff. A friend and neighbor had several ground loops each resulting in fuselage damage. I helped with the last one. The damage was always in the same areas. It strongly suggested that bending the tubing to the original shape does not result in the same strength you get from new straight welded in tubing. He cured the ground loop issue by a bit more practice.

This time we replaced some of the tubing. That in itself is a challenge as access is very difficult especially with TIG. We also made some gussets to help stiffen the tubing we didn't replace.

[cgruby]

A good reference book is FAA manual AC 43.13-1B/2A (formally CAA Manual 18) "Acceptable Methods, Techniques and Practices, Aircraft Inspection, Repair & Alterations". Chapter 4, Metal Structure, Welding, and Brazing covers this type of repair. In fact anyone who is doing their own repair or better yet, building an aircraft, should have this most valuable book.

I think A/C Spruce or Sporty's may have them for sale.

Having just gone through an extensive repair due to a towing accident, I have had to straighten and replace a lot of tubing. Sometimes it's better to simply straighten a tube, and then weld in a reinforcement.

One thing I would like to add. Be careful about changing the design by adding or removing structure. Sometimes, simply adding a gusset to reinforce a joint, will in-fact transfer the stress beyond the gusset and cause a failure downstream where the addition was made.

Good Luck,

[Jch]

AC43.13 can be downloaded from the government web site and opened in IBooks on an IPad for free.