Acceptable Repair??

Guy's please have a look at the attached pictures and let me know what your thoughts are. I found this upon removal of the fuel tanks which had been jarred loose on the nose over prior to my purchase of the plane. Appears to be a previous questionable repair. The only thing I can find in the log books for previous damage was a gear failure causing a prop strike, no mention of wing damage. Maybe done by the original builder before covering??? I guess my question is that the repaired rib did not suffer further damage in the latest nose over so is it acceptable to ignore this? The pics are of the 4 th rib out from the fuel tank.

That is likely not an airworthy repair due to incorrect selection of adhesive and no reinforcing material around the cracked areas. AC 43.13-1B provides general guidelines for acceptable repair methods. http://www.faa.gov/documentLibrary/m...AC43.13-1b.pdf Take a look starting around page 1-83.

I would be concerned with the construction and other repairs which might have been made. Are there any inspection ports you could open to survey the rest of the structure?

Thanks for the reply Paul. I have had a good look through AC43.13 and can't find the page that you recommend. Section 1 ends at 1-71 on page 1-37. I did find a section that refers to rib repairs at 1-46 on page 1-18. It does show using plywood laminate for rib repairs but appears to be wooden ribs not plywood ribs. With reference to the adhesive used; do you have any thoughts on what this may be and what should have been used?

Kurt, Any good structural adhesive is acceptable provided that when you glue up a test sample and pull it apart, it pulls wood and does not separate at the glue joint. An excellent glue is T-88 which Aircraft Spruce sells (along with others). Also, the Loctite 9460 Hysol used in assembling your aircraft should be adequate. The important thing is preparing the glue joint. It's got to be free of any finish, clean and should not be sanded. You need to provide adequate clamping pressure, but not to the point where you squeeze out all the glue.

Make you a test sample and pull it apart. This is a good confidence builder and will demonstrate to you, the strength of the repair.

ps: I failed to mention, that you will need to splice any break with additional material. Don't simply rely on the glue to bridge the gap. Use the FAA's book as a guide.

Good Luck,

Are you looking at the 1B version of AC43.13 that I linked? The referenced page is in there. Also, the same information can be found in an FAA handbook: https://www.faa.gov/regulations_poli...a/ama_Ch06.pdf

I would obtain some aircraft grade plywood matching the original rib and capstrip material. Clean up any cracked rib area and sandwich with plywood on either side. Capstrips should carefully have the damaged areas cut out and replaced with scarfed in material. I think I would also support that with plywood across the joints on the bottom of the capstrip.

As for glue, I'd go old school and use Resorcinol if your fitups are tight and you can clamp the repair area adequately.

Great advise guy's, I have done some more looking into this questionable patch job. This was definitely done by the builder prior to covering. The reason the adhesive looks different is that it is covered with varnish. Everything under the fabric is covered in varnish including the spars. The adhesive underneath the varnish is Hysol. After pulling out the LH fuel tank I found 2 other questionable joint repairs. Needless to say I have committed to pulling all the fabric off and checking for any further anomalies.

Paul, I was looking through a copy of AC43.13-1B that I have saved on my computer. I will check the linked version. Are you referring to page number 1-83 as the document page or the PDF page? The contents in my saved copy goes as follows. Chapter 1 Wood Structure, Section 4 Repairs which ends at page 1-31. Sorry for the confusion.

I believe it's the document page.

Looking at your pics the middle one seems to be the most worrisome. Is the wood actually cracked? If so you need to repair it by removing the affected area and applying a patch with a scarf joint. Might be easier to just replace the rib. I am building a GP-4 in parallel with a KF V :eek: I am pretty familiar with scarf joints! EAA has a pretty good book on wooden aircraft structures.
Remember - extra glue is just extra weight... Nice smooth fillets and good contact with the two parts. With T-88 a tight joint is not required but good workmanship pays dividends in unwasted adhesive.
Regards
Jeff