Broken rib stitching

[Dana]

I have a Fisher 404 that hasn't flown in about 10 years. The issue is the rib stitching, or lack thereof. As near as I can tell, this design (95 mph Vne) allowed glue to secure the fabric to the ribs in lieu of rib stitching. On my plane, I don't know whether glue was used (some of the fabric is stuck to the ribs but some is not), but the builder rib stitched it not with the usual waxed chord, but with what looks like ordinary sewing thread, most of which is broken. Anyway, the A&P who's doing the condition inspection and I are discussing the best way to deal with this, the safe answer being to strip the fabric (which is in good shape) and , My thought is to restitch the existing fabric, with new finishing tape over it, but the A&P's concern is that it isn't a documented "standard" repair technique so he's reluctant to sign it off. Thoughts?

[Jim Hann]

Dana, I had this exact issue with my certificated PA-22/20. Ceconite has no leeway on the stitching, I would have had to restitch exactly in the same holes which meant soaking off the tapes and doing all that labor. I elected to recover the wings and tail.

Since yours is an EAB, you can stitch it however you want, as long as an A&P will sign off the Condition Inspection. Recovering is probably the easiest way to do it, although not the cheapest. If the fabric was applied in full accordance with an installation manual I would say consult that company. It sounds like it wasn't done that way, so I don't know who you would turn to. Of course some folks will say it is an EAB, you can fix it any way you want! The amount of labor involved with removing all the finish tapes and broken stitching cord isn't a big deal if you want to do it yourself.

Good luck with your decision.

Jim

[1600vw]

When doing the repair on my airplane. We did not have to soak the tape to get it off. After I cut it with a knife I was able to pick it up and just pull it off. This to was ceconite fabric. If I remember correctly the old system used was poly. We used the Stewards System for the repair. After a few years it looks good.


I was not showing this repair in these pics but you can see it on the wing. I have not finished matching the blue paint. The airplane is getting new fabric in the next year or so.

[rwanttaja]

I have a Fisher 404 that hasn't flown in about 10 years. The issue is the rib stitching, or lack thereof. As near as I can tell, this design (95 mph Vne) allowed glue to secure the fabric to the ribs in lieu of rib stitching. On my plane, I don't know whether glue was used (some of the fabric is stuck to the ribs but some is not), but the builder rib stitched it not with the usual waxed chord, but with what looks like ordinary sewing thread, most of which is broken. Anyway, the A&P who's doing the condition inspection and I are discussing the best way to deal with this, the safe answer being to strip the fabric (which is in good shape) and , My thought is to restitch the existing fabric, with new finishing tape over it, but the A&P's concern is that it isn't a documented "standard" repair technique so he's reluctant to sign it off. Thoughts?

I believe that Fisher specifies only gluing the fabric to the ribs, that the instructions don't include rib stitching. Nothing wrong with rib stitching, of course. The argument could be made that the existing rib stitching is superfluous.

I used to have people complain when I left one of the 13 screws off a particular inspection panel on my Fly Baby. I would point out that the designer specified only four. Eventually I installed a panel with only four screw holes....

Ron Wanttaja

[1600vw]

My Blue prints show rib stitching. But this is the V Model. My first Avenger did not have rib stitching. It was not the V model. I did not have blue prints for that airplane.

Tony

[Dana]

Fisher only specified gluing, but the original builder stitched it (it's unclear whether he used glue as well; some of the fabric appears to be adhered to the ribs but in other places it clearly isn't). Perhaps he thought the stitching was superfluous and that's why he used such light thread, but at any rate, the stitching has failed and so has the glue (if it ever was present).

My position is that restitching through the original finishing tape, with additional tape over would be stronger than the original that lasted over 350 hours, but as Jim points out the A&P will have to be comfortable enough with such a repair to sign off the condition inspection... which he's reluctant to do.

[martymayes]

Dana, imagine you had given the aircraft a "pre" condition inspection and noticed the broken rib stitching. So you pull out a roll of stitching cord and go to work. Then install a finishing tape over the new stitching and touch up the paint. Would the A&P have had any issues? Of course not. Now he's convinced himself nothing short of a complete recover will be adequate.

I know what I would do. With your past ultralight experience, I have complete confidence in your abilities.

[martymayes]

I believe that Fisher specifies only gluing the fabric to the ribs, that the instructions don't include rib stitching. Nothing wrong with rib stitching, of course. The argument could be made that the existing rib stitching is superfluous.

Is there any fabric covering system where the manufacturer will say no rib stitching is required in this application, our glue is more than adequate to hold the fabric to the ribs?

[Dana]

The Ceconite manual says rib stitching (or equivalent) is required, but it was written before such slow light aircraft, borderline ultralights, were common. Oratex (the new iron on fabric) says "That just depends on the requirements as set forth by the designer of your aircraft. If the plans call for rib stitching, then you must rib stitch. If the plans call for rivets, you will use rivets."

Any repair is complicated by the fact that the builder painted the plane with automotive enamel over the dope. Beautiful, but trickier to repair. I don't want to have to remove the existing finishing tape since removing the enamel, the the dope down to the clear coat, would probably be more work than a full recover. However, I can't see any reason why it would be a bad idea to stitch through the existing finishing tape, and apply new tape over that. Oratex tells me their finishing tapes can be applied over any existing finish provided that original finish is still secure to the fabric.

[1600vw]

My Fisher plans do not say to use rib stitching. But the blue prints show the ribs stitching in place. Auto paint was used on my airplane and the repair was easy. I too was worried about this auto paint and how hard it would be to repair. It was a non issue.

Again I used the Steward System and it was an easy repair and has held up great in the 3 years its been on. This winter it will be going into the 4th year.

Tony