Is this worth messing with?

[mbutler]

kitfox damage5.jpgI recently purchased a 912s (4hrs) along with prop and avionics off of a damaged 7SS also 4hrs for a future project. I may have found my future project, the damaged 7SS. Is this worth messing with or should just start over?

thanks Michael

[kitfoxnick]

Absolutely

[Av8r3400]

Looks like a pretty easy fix to me. A little cutting and welding along with minimal fabric work.

What's the rest of the airframe look like? Just a nose over, main gear impact?

[mbutler]

main gear, wing tip (1 rib), right flapperon and rudder horn damage. I can send main gear to Grove for repairs, purchase new flapperon, rib and material for new rudder from Kitfox I hope. My concern is both doors don't close, not sure if the fuselage is out of alignment and can it be straightened back up.

[Paul Z]

I would repair it, it's a 7 Super Sport. If the door damages is the only damage to the fuselage frame, even if you have to hire a welder to come in it looks relatively minor, but it will take some welding. I'd replace the door frame tube, and straighten the bottom frame tube out and have some gussets welded in. Looks like a great find.

[jtpitkin06]

Quite often when you cut out a bent tube on an airframe much of the remaining frame will return to near new alignment. Repairs like this are not difficult. Sometimes you may require a bit of help from some body shop type hydraulic rams and pullers that you can rent or borrow. Ask around.

John

[cgruby]

Mike, From what I can see it as though we discussed on the phone. Strip the fabric back to expose the damaged components and straighten as we discussed. It looks like a pretty long section of the lower longeron is bent. You may have to get a pretty stought rig to hold the fuselage while you pull that out. Be sure and take a lot of pictures before you start tearing everything apart.

Good Luck,

[HighWing]

I think I'd go for it, but a couple of thoughts. A friend who rents a hangar nearby and flies a Light Squared has damaged his airplane twice on landings. The first time, he straightened the tubing, patched the fabric and flew for a few months and then did it again.

I helped him with the second repair largely because a couple of the tubes were broken and it needed some welding. On checking for what needed to be done, I notices some tubing that had dents or other deformations from the previous damage (repair). My guess is that played some part in the more severe damage the second time.

I am not an engineer, but I suspect if you can't straighten the tubing exactly, they will not be able to withstand some of the compressive forces they are designed for. We welded in some new tubing and straightened some. We also added some gussets but they are bonded in with Hysol. I had been thinking on that technique for some time and it simplified the welding process a lot. Again, not being an engineer, I supposed the forces tending to bend tubing are not large forces so I slit lengths of appropriately sized tubing in half and welded them on the edges of carefully cut .032" 4130 sheet. when positioned, they capture about half the diameter of the structural tubing with the Hysol bond and there is a bit of play for the perfect fit without distortion.

All this being said, I have read that over building some areas will add stress to other engineered areas - engineered with no consideration for our modification.

It has been about six months and the friend flies almost every day. So far so good. Our fix is either working or he has improved his landing skills.

[Paul Z]

I see you are in Cross Plains Texas, I have landed in Eastland a couple of times on a trip to El Paso. If you would like someone to come look at it an give you a second opinion after seeing the extent of the damage, I would be willing to come over. I am in the Dallas Area.

There definitely are some thing you shouldn't do:
Don't use a hammer to hammer and bend the tubes straight.
Cut out the badly bent tubes as close to the adjacent tubes as possible.
Grind the cut tube almost flush to the adjacent tube.
Cut and radius fit replacement tubes.
Make sure you have a good fit, and then clean and sand the paint off prior to welding.
Finally have a competent welder weld the replacement tubes in place.

Feel free to Private MSG me if you are interested in a second opinion.

[mbutler]

Thank you all who have replied to my post. I will start by cutting out the bent tubing and go from there. If all goes well hopefully I can get it back flying sooner and with less cost than I expected. If it doesn't turn out like it should be I will replace it with a new fuselage weldment.