Mailing List lml@lancaironline.net Message #37961
From: Guy Buchanan <bnn@nethere.com>
Sender: <marv@lancaironline.net>
Subject: Re: Shudda gone down when the buzzard went up
Date: Tue, 03 Oct 2006 22:30:41 -0400
To: <lml@lancaironline.net>
At 03:06 AM 10/3/2006, you wrote:
Looks like the leading edge was forced back to the spar by the initial impact, flexing and tearing the skin as it deformed. A large flap of skin folded back, forced up to vertical by the airflow, formed a very effective spoiler in front of the aileron. It took full stick and lots of rudder to keep the blue side up.
 
Where does one begin a repair like this?

First you have to find all of the pieces of the buzzard. Then you lay them out on a big floor. Next, starting with the beak, if you can find it...

Oh you mean YOUR plane! (Sorry. Gallows humor.)

You begin by determining the scope of damage. There are a couple of ways of doing this. The "simple" way is to start removing material until you reach undamaged hardware. I say simple because it takes diligence and sometimes expertise to recognize damaged versus undamaged material. And sometimes damage occurs in odd places, away from the obvious damage. (You'd be amazed at what that wing probably looked like just before the leading edge failed.) Unfortunately, even if you remove all the obvious damage you will probably want to invoke the more "complex" assessment methods, which is to use non destructive testing (NDT). With cored structures it is entirely possible that the shock of the impact and/or amount of deformation prior to failure has precipitated core failure far beyond the region of obvious damage.

Since you have cored structure you can have some success with thermal imaging. In the solid regions you might be able to use ultrasonics. Suffice to say these methods require extensive expertise well beyond the capabilities of the average builder. You'll have to bring in an NDT consultant to do the work, and it will be expensive, and not conclusive.

Once you determine the scope of the damage you determine the type and scope of the repair. It is certainly possible to affect a local repair, even one this extensive. You'll gain a little weight, which you'll have to balance in the other wing, but it can be structurally and cosmetically sound. I can help with the design, and I'm guessing Dan Newland would be willing to help as well. There may be other composites experts on the list I don't know about.

My recommendation, on the face of what I saw in your pictures, is to seriously consider replacing the wing. It's not that I lack confidence in a repair, but it may take you longer to do the repair than to build and install a new wing. (Or find a replacement somewhere.) You'll have to try to assess the time it would take to replace the wing, but I can tell you it will be a big job to do the repair right. (It's somewhat quicker to do it "the fast way", but it will be heavy, and probably visible.)

Oh yes. Congratulations on your recovery. We have a lot of large bird activity here in Ramona and I often wonder what happens when you hit one.

Feel free to contact me off-line.

Guy Buchanan
Principal
Buchanan & Newcomer
16718 Peace Valley Lane
Ramona, CA  92065-7046
USA
1-760-789-4482
1-760-809-6145: Cell
bnn@nethere.com

Subscribe (FEED) Subscribe (DIGEST) Subscribe (INDEX) Unsubscribe Mail to Listmaster