Compromised spar lip

you can get the drawing for the spar caps from Harmut's site, that should help the DER.

Thanks Ed and Arlan.  The advice seems sound and well considered.  As it turns out, I have in fact found a DER who has at least replied to my emails.  My son the A&P actually located him by way of one of their customers who apparently had similar problems with a 172.  This DER out of Denver solved that problem and indicated to my son that he has a particular interest in keeping old planes flying.  So far, I've sent him some pics of my plane and he replied, saying that he'll send sketches to indicate where he needs more and some dimensions that'll be required for him to assess and possibly come up with stress analyses and engineering drawings.  We'll need to formalize an agreement before it all happens of course but so far, he has declined any payment for services and my son says his rates are quite reasonable. 

I'll try to keep this thread updated as progress is made.

Chris

I agree with Allen, do a lot more research and be sure of your terminology before contacting others - some are too quick to say "NO", it's so much easier.
Reason I say this, I just spent a few minutes in AC43.13 as Allen suggested. One item in there says, "if part to be repaired is CAST", no repair, only replacement. Is it certain that the spar is "cast" as opposed to "extruded"? If extruded, probably the proper repair can be designed using angle material as shown in 43.13. As Allen suggested, do your research, and then contact a DER with your data package - if the first DER doesn't sound interested/reasonable or competent, contact another. I would not seek an FAA approval unless I had previous comparable 337. Doubt if you will find many FAA personnel at FSDO level qualified to approve. Others may comment re the cast viz-a-viz extrusion on the early models. 2c FWIW

Do some research in AC 43.13.  With the absence of Manufacturers repair data best practices should be acceptable.  

 After  researcring talk to your A&P/IA.  If in doubt locate a designated engineering representative (DER).  Talk to him about working up a plan for repair.

Well, it looks like that now, since the cat's out of the bag, I'm fairly screwed as far as selling the plane as an airworthy unit goes. There are basically 2 schools of opinion from a host of people who've looked at it now that it's home with the wings off so a good inspection can be had.

Some say that this is such a common problem as to be almost universal in Ercoupes below a certain serial #, ie the ones with the tubular steel gear legs instead of the cast aluminum I-beam style. The cups that retain the rubber shock absorbing discs are stretched enough over a life of landings and takeoffs so that they contact the rear spar lip and at least bow it out if not crack it. There are apparently many others like mine that have been repaired in the field (hopefully by a more qualified mechanic who did a better job) that are signed off year after year at their annual inspections without a problem.

The other school says that because the damage involves the spar, even if it's the rear lip, which is a cast part, and even if that rear lip is not considered structural because it's made of thinner material than the front lip, there is no way it can be considered passable and the entire spar requires replacement. If that's the case, then even if school 1 has a chance of being right, there's no way my conscience would let me sell it to an innocent buyer without full disclosure of the disagreement and if I were that buyer, I'd definitely walk away.

So, I can let someone trailer it off into the sunset with wings off as a repairable plane, or just part it out, probably for about half of what it would have been worth. Anyone out there need a project?

If indeed those show a cutout and stop drilling of the lower spar cap web, the prebuy mechanic knows what he was looking at. You may have a problem if that is the case.
carl