Spar AD and Rib Nail AD

5

_54Ed

New member
Before I make a decision, I like to think hard, gather information, and get advice from experts ... then disregard it all and learn things the hard way.

Aircraft buying is no different. For my first plane, I figured that I could save a little dough and skip the pre-buy because I was only buying a 1/4 share of an 8KCAB. I had a friendly chat with the long-time mechanic instead, who assured me that all AD's were complied with.

So now here we are at annual time, and I discover that we have no documentation for the wood spar AD being complied with. We also have obviously not complied with the Rib Nail inspection requirement in a long time, because we are missing plenty!

The NEW mechanic is a meticulous fellow, and he insists that we need to add a whole bunch of additional inspection rings/holes to the bottom of the wing to check and fix the rib nails. It adds up to almost one hole per rib, front and back. He also strongly recommends that we add the inspection plates to the top of the wing to inspect the spar at the strut attach points.

My partner is adamant that there will be no new holes. I'm agnostic about it; I don't know what is the right thing to do.

Has anyone else crossed this bridge? How many extra inspection holes did you add beyond the original factory holes? Did anyone go with the "optional" inspection plates on top?
 
Hi,

Make sure you read the AD and all the material pretaining to the spar AD. I wouldn't want inspection holes on top of my wings and they are not required to do the inspection. You can find a lot of good material including the AD and the procedure's for inspection here on this site. As for installing the inspection holes that's not a real big deal and if your mechanic will allow you to you can install the things and it dosen't cost a fortune to do it. It's kind of like going each year for a prostate exam, no one wants to go get the exam but once you go dosen't it make you feel good that everything is alright, also if there is a problem chances are it isn't going to kill you if you've had you're exam each year. My son's a Urologist,had to put a plug in for them!


Woodie
N29763
 
Still looking for comments on fiber optics and spar inspections. We have tried the old sigmoidoscope, and the idea is excellent, but the darn thing is designed for one-dimensional travel, and we need to look in 3 dims. I am betting that one could do a super spar inspection with the right tool, without a billion inspection holes!
 
My wings have had the Rainbow covers on the top since the late 90's. In addition to the proper number of holes to see each rib bay.

If you are going to do acro, you may find that this is an increased sense of security.

The holes on top allow you to inspect the spar doubler, and the metal bar that picks up both struts, and connects front and rear spars. The only caution is that when you re-seal the covers, you should use a little silicone.

The inspection goes much faster with the covers, and they are easy to remove or re-install.
 
Definitly, I cut all the required holes under the wing, then purchased the rainbow kit for the top! Easy to install and no trouble deciding what you are seeing in the mirrors! also without all those holes in the bottom of the wing I never could have serviced all those missing nails! I also made a little slide hammer to install the new nails it made it very easy to drive the new nails in such tight spaces! Also I was very happy with the recessed covers or flush covers from aircraft spruce! They never move and look nice also, they lay into the wing very nicely and do not get anyones attention! Lots of holes but I really want to see what should be seen! The rainbow covers were a nice fit also, just be carefull when you trim the leading ede skin so that you do not scratch the varnish on the spars or worse, they trim very easy with aviation snips, I also placed a sheet of scrap aluminum over the spar while working just in case I slipped. I would not have done it any other way looking back!
Good luck friend!
 
I also made a little slide hammer to install the new nails it made it very easy to drive the new nails in such tight spaces!

Sorry about the previous post....I was wondering what your slide hammer looked like and how it was constructed. Sounds like a good idea! Any Pix you can forward? Tailwinds, Steve.
 
If I can butt in here a minute I'd like to add a little of what I've found in Decathlon wings.

If you've got missing nails, you've probably also got some ribs chewing into the spar. The ribnail service letter explains just how much is allowable, over an eight of an inch and the spar comes out for replacement.

But if your particular airplane has been flown aerobatic a lot, there is the possibility of a bigger problem. The ribs tend crack at the spar cut out, usually in the nook of the radius just forward of the spar. I repaired one airplane that had just been recovered a year before, yet nearly all the ribs were cracked and many were completely seperated from the rest of the spar.

A symptom of loose/ broken ribs is to do a roll and see if the airplane flys in a skid or one wing low once you've stopped the roll. If wiggling the ailerones back and forth caused the skid to disappear, than you've probably got broken off nose ribs floating around and not supporting the leading edge properly. Snap rolls will quickly exacerbate any cracked rib issues

The fix was to split the fabric at the leading edge and fold back to the spar and rivet on reinforcements available from safe air repair. I think I did something like 24 ribs and there were 4 reinforcements per rib. Something like 800 bucks for the parts, and that was 15 years ago.
 
Every time I did accro in our Citabria, with my kid in the back, I wondered about the compression cracks. My partners finally gave in and we rebuilt the wings with the Milman Engineering aluminum spar kit and we are very happy with the plane...no more spar inspections...1.75 times as stiff and much stronger. Milman Engineering was very helpful and we did the job, including repainting of the entire plane with aerothane, for about 60% of the Champion installed wings.

Before we did this we tried borescopes, mirrors, lights, etc but we refused to put a bunch of holes in the top of the wings.
 
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