BC12 Wing Spars

[taylorukuk]

I have finally sourced some spruce for the new wing spars.
1 x front spar and 1 x rear spar are perfect spruce with no defects , straight grain etc etc

However the other set of planed spruce each has a defect. I have attached pictures above and would be grateful for any comments - Serviceable or scrap?
(perhaps could be used by scarfing onto existing cracked spars)

The first spar looks like it has a pitch pocket which is not all of the way through the depth / second picture perhaps bird peck or mineral streak?

Any thoughts appreciated.......

[Hank Jarrett]

Needs to be inspected by someone who really knows wood. This is REALLY nice wood so certainly NOT scrap, but might not be spar material. You do know that Taylorcraft used many laminated spars so it could be ripped to remove the damage and re-glued together as a laminated spar worst case. As expensive as this kind of stock is it is WELL WORTH having it inspected, in person by someone who can tell you for sure before you start cutting it!

[taylorukuk]

Hi Hank

Yes - Option 2 is to laminate a spar out of it.

BR Ian

[3Dreaming]

I would talk to the person who will be signing off on the airplane when repairs are completed. I know as a mechanic I wouldn't want to see this when doing an inspection on a completed wing.

[Hank Jarrett]

The best IA to ask for advice is almost always the one you want to do the signing off! Multiple opinions are always good, but the guy signing the log book is the one with his behind on the line.

[Ragwing nut]

Refer to AC43.13

[N96337]

AC43.13 will give you some criteria, and is a good place to start, but I would actually, refer to ANC-19
Tim has put a copy on this site.
Depending on where in the length of the wood the defects are located, and a few other factors, I might use them. The further they're located outboard of the strut, for instance, I'd feel more comfortable.

John

[taylorukuk]

I have referred to AC43-13 and ANC-19 and Mil spec MIL-S-6073 but they are all a little vague.

[Ragwing nut]

I have referred to AC43-13 and ANC-19 and Mil spec MIL-S-6073 but they are all a little vague.

I'm pretty certain ac43 gives you the max size for the defect allowed. grain deviation looks fine. Depending on size I would run them.

[Hank Jarrett]

Being "vague" with advice is always an out where being wrong can get costly (like your customer looses his plane or life). That is why I like getting a respected IA to accept it in the log over looking in the book any day. This one is BAD. No question and I will stake my reputation on it.

[Hank Jarrett]

Whatcha think? Little glue and filler and she could be good to go?

[Hank Jarrett]

Little sandpaper and a new doubler and no one will ever notice.

[Hank Jarrett]

I have just a few really nice examples of how bad a spar can get. LOTS of good wood still there for making some furniture. I can't even figure out how this one got broken?!?!?! How does a spar break like that and not tear the skin to pieces?

[astjp2]

Much of those defects will depend on location, size and depth. The top one I would run as long as it is not in a wing attach to strut attach zone, the bottom one I would prefer outboard of the strut attach point. Jmho Tim

[taylorukuk]

Thanks for all of your input.

I took some measurements and had our Chief Engineer at the Light Aircraft Association have a look at it today.

They are all good to use due to the position of the defects and just require the ply gusset on the spar attachment point extending slightly over the defect on both sides.

Thanks for all the posts - Good advice