BC12-65 Wing Rebuild

[shipljl]

I recently acquired a B12-65 with a damaged right wing, and the leftwing looks like it is original. I plan to rebuild both wing. I appreciate any advice you can give me.

My first question has to do with corrosion proofing my ribs. For weight saving reasons I would like to strip the ribs and alodine them. Is there any reason that this isn't a good idea? One wing has bare aluminum (apparently the way they were made, the other has painted ribs). Is it ok to alodine them?

Also, does anyone know a source for the folded aluminum "T" stock that the ribs are made of? I saw a photo sequence of a restoration of a BC12-65 online where some of the ribs were replaced with ribs formed from a flat sheet; looks like they came from a later BC12-D. Is it ok to replace damaged "T" ribs with the later sheet ribs?

[TonyL]

Re: BC12-65 Wing Rebuild

Hi
I'm restoring a BC12D. You're right. some of the ribs, primarily at the trailing edge section were not painted. Remember, if the Aluminum is clad (Shiny) that is a corrosion protection. Using alodine the primary precausion is, a very good rinse, to neutralize the chemical action after application. The ceconite 101 manual calls for epoxy primer. They recommend white. If you're trying to stick to the green, so be it. Manual says don't use bondo, use superfill. Everyone told me , to use bondo because superfill was hard to work with. Used superfill, It's surprisingly workable. If you don't have a manual, I found a free download for a 1997 version. The latest version is 2008. The newest version is really good. Got it from Aircraft Spruce. The old version, I can e mail to you as an attachment. Better yet, I can send it to the foundation for all the members. I have an extra copy of the latest version, this is a hard copy, would have to figure how to get it to you. Incidentally, I used the gray epoxy primer. Couldn't find the white fast enough. The lighter color is recommended by the manual. If you're going to register it, in the normal category also a form 337 may be needed. The foundation has a sample in this web site. The manual for the 2008 has the STC no. which should be used to reflect adherence. Have fun!!!!!

[shipljl]

Re: BC12-65 Wing Rebuild

I am ready to bond the plywood doublers to the spars. I have a question about preparation for bonding. The resorcinol adhesive says that the wood should be milled no more than 24 hours before bonding. That's fine for the spar root doublers, but what about the mid-span lift strut doublers? It would appear that they have been directly bonded to the spar without removing any spar material. I thought about sanding the spar to expose fresh wood but the AC says not to sand soft woods like spruce before bonding. Any advice? Should I mill a very small layer off, should I sand, or should I just bond to the existing wood which is at least a year old at this point since being cut?

[Hank Jarrett]

Re: BC12-65 Wing Rebuild

Is there already a finish on the wood? If it is varnished or there is glue for the old doublers a scraper would probably be best. You can expose the wood without removing enough to measure with a good scraper or the edge of a piece of glass (be careful with a glass scraper, it will take tiny bits of wood when used right and HUGE bits of flesh if used wrong and it breaks!)
You should NOT sand the wood. You can never get all of the "dust" out of the grain and it will lower the bond strength. You can take off as little as a few ten thousandths with a scraper and keep it perfectly flat while you do it. Try and find a really good furniture restorer to show you how. Good wood scraping is becoming a lost art and is worth learning.
It is also one of the best ways to remove old finish from a spar before re-varnishing. What wood you remove will be less than the allowable dimension variance new from the factory. No planner or drum sanding machine can match the quality of the finish with so little removed.
Hank

[shipljl]

Re: BC12-65 Wing Rebuild

Thanks for the suggestion. This is a new spar so there is no finish, however, I like the scraping option much better than milling.

[shipljl]

Re: BC12-65 Wing Rebuild

Riveting on pre-war ribs is proving to be a challenge. The narrow grooves make for difficulty in getting rivet sets, bucking bars, and rivet squeezers in place. Does anyone have suggestions for riveting these ribs? Can Cherry Max rivets be used?

[Larry Lyons]

Re: BC12-65 Wing Rebuild

I can commiserate. I have screwed up several rivet attempts on my 41, so much so I have stopped until I find more ribs or better rib material to splice in.
Larry

[Dot_AK]

Re: BC12-65 Wing Rebuild

I just got the last of my ribs (except the butt ribs, which are a different and long story summed up by "whatever makes my IA happy, sure, you betcha") repaired last week.

First, a good hand squeezer is absolutely incredible compared to trying to maneuver a bucking bar. Second, take your rivet sets for the hand squeezer, find someone with a lathe, and get them turned down to just a little larger than the shop head, and just large enough to not compromise the dimple that hold the machined rivet head. This made my life infinitely easier. Third, get not only the size of soft aluminum rivets to replace your factory ones, get the next size up, too, for when you might perhaps misdrill a rivet out and need to fill a bigger hole. Turn those rivet sets down in the lathe, too! Fourth, not only is a hand squeezer wonderful, a hand-squeezer with the head set in a vise so you don't have to hold it still makes getting rib, rivet, repair, and rivet sets lined up ever so much smoother. Fifth, clecos come not only in wonderful fill-the-hole form, but also in "edge clecos" which clamp down without getting in the way.

Sixth, a set of pliers with the ridges taped over so the don't mark the aluminum help squeeze things back together and hat channel down so rivet sets and rivets fit in easily to be squeezed. Box pliers do even better along a long section, sometimes.

Seventh, For riveting inside the original W-channel, I finally settled on using a bolt instead of turning down a rivet set any smaller - the bolt head was just barely big enough to fit inside the channel, as the dimple squezed the rivet head from the backside. If you do this, prepare to swear. Um, I mean, prepare to have to set it really precisely and drill out more rivets that didn't smoosh quite right.

On repair parts, there is a piper cub rib repair kit that provides short sections of L-angle for the part you nail into the spar replacement, W-channel to replace the middle bits (though it's wider and shallower curves), T-stock that is not the same but can be spliced in, and hat-channel that can be folded around to reinforce weak spots or join two sections instead of splicing by opening the T-channel and shoving one inside the other until you have enough overlap to rivet.

On the other hand, if you need repair stock, I have about 7 ribs* that I put aside as too damaged for me to want to immediately repair after I got ahold of some in-much-better-shape originals, and quite a few sections of the afore-mentioned repair kits. You could tear it apart and salvage most of it for repairs, or if you have more patience than I currently do and want to put a jig in place for forming, you might be able to repair them entirely (most of them have corroded noses, and reforming that curve makes me say words my father would not be proud to hear me using.)

I know I forgot something else simple. Oh! Get a larger drill bit, and gently by hand run it around the edge of any holes you drill - it helps get rid of burrs and bevels holes so the rivet goes in ever so much easier, and lays flat.

*I think it's actually 13 because it was most of a spare wing, including hardware, but I'll lowball this until I pull the bundle out and count it. If you're interested, I can find a camera, document the damage/ repairs needed.

[mulwyk]

Re: BC12-65 Wing Rebuild

Great post.

Yes, pictures.

[shipljl]

Re: BC12-65 Wing Rebuild

While looking at the main spar on my "good wing" on my BC12-65 I noticed something that bothers me. According to the logs, this wing is original but I have found many things about this plane that aren't documented in the logs.

The issue is with the lift strut attachment on the front spar. There is a short piece of steel tubing controlling the separation of the lift strut attachment fittings just below the spar. On this spar there has been a half moon groove cut in the bottom of the spar to accommodate the short piece of tubing. It looks like someone cut it into the spar to make up for having the bolt holes too high up on the spar, and they cut a groove in the spar to make the fitting fit. The other "not original" spar on the other wing does not have this groove.

I have a hard time thinking that it was ok to cut a groove in the extreem fiber of the spar. Does anyone know if this was standard or accepted practice?

[Leenicklas]

Re: BC12-65 Wing Rebuild

Does anyone out there know where to get the nipples and lock nuts that are on the drag wires: A-8089 and AN315-640 respectively? Lee Nicklas

[Guest]

Re: BC12-65 Wing Rebuild

for AN315-640

http://www.aircraftspruce.com/search/search.php?s=AN315-640&x=21&y=16

How many nipples do you need and how much will you pay for each one?

[Helicopter D]

Re: BC12-65 Wing Rebuild

I ordered all new Stainless drag wires and nipples from Wag Aero, the wires are 12$ and the nipples are $6 each. I have about 75 of the stainless check nuts for drag wires left over and would be happy to send you enough to complete both wings.

[Guest]

Re: BC12-65 Wing Rebuild

I ordered all new Stainless drag wires and nipples from Wag Aero, the wires are 12$ and the nipples are $6 each. I have about 75 of the stainless check nuts for drag wires left over and would be happy to send you enough to complete both wings.

Excellent find!

Wonder if they have the drag struts too?

Dave

[Guest]

Re: BC12-65 Wing Rebuild

oops! no drag struts but they have good prices on the selection that they do have