where to buy spars

[alwaysoar]

Re: where to buy spars

I understand that spars and about anything else can be "owner produced." My question is whether or not spar blanks must be aircraft grade: gov't specs, slope not greater than 1:15 in grain, specific gravity of not less than .36. Owner produced or not, installation of a new spar requires a 337 as a major repair. Right? If the spar blank is not aircraft grade, then it would not satisfy the requirement in owner produced parts that it must be built to original specs and that documentation showing that must be entered in the logs. The non-aircraft sources of spruce mentioned in this post would not necessarily provide blanks that meet the specs, and therefore the spars would not be legal. IMHO--please correct me if I'm wrong.

Ed @BTV VT
TF 527

[8708]

Re: where to buy spars

I am having my tcraft restored at the factory. I was in BRO this weekend and spent the afternoon with my project. It is looking fantastic! Anyway both my wings now have new spars and they have them in the factory. They have the jigs that make drilling the holes in the right place a cinch. I would give them a call.
Jay

[Acroeric]

Re: where to buy spars

In reality you could cut down the tree and mill the wood yourself as long as it was determined to meet the specifications. Where you buy wood only matters if you do not have the resources to evaluate it. AC43.13 1b chapter 1 has some great info. on the subject.

As for the T-88, it does soften with heat and is not approved for use on anything certificated. There has been really good results with it's use on high performance aerobatic aircraft, no failures that I am aware of. Sean Tucker and Jim Leroy both fly +9 / -6 G airshow routines on wings built using T-88. I think they probably push their aircraft harder than anyone on this planet!

I still plan to use it on my ribs but I will use resorcinol for my spar doublers on my experimental clipwing.

[Acroeric]

Re: where to buy spars

I ran across this from the manufacturers of T-88. Yes it is still not approved but it certainly works well. The fellow sheds some educated insight on the test set up as well: here it is-

As the producer of T-88 no one is more interested in this subject than we are.
T-88 has been used in wooden aircraft construction for over 25 years and we do
not yet know of a documented case where a glue failure has occurred on a light
colored wooden airplane because of heat.


I suspect what you are referring to is ASTM D648. a test for the heat
deflection temperature of polymeric materials. This test takes a half inch
square bar of the polymer 5 inches long and suspends it in an oil bath on four
inch centers. A load is then placed on the center of the bar and a deflection
gauge is zeroed. The oil temperature is raised one degree C per minute. At
the temperature the bar deflects 0.01 inches is defined as the HDT. For T-88
this is around 122F.


The HDT has nothing to do with a 28 per cent loss in strength. There might be
a 28 per cent loss at the glass transition temperature which is about 145F for
T-88. Still, even there a twenty eight per cent loss leaves a safety margin
of at least 300 per cent (as opposed to 400 per cent at room temperature).
Furthemore, wood is an excellent insulator and a plane sitting on the ramp for
thirty minutes will barely raise the temperature of the interior of the glue
joints.


The caution with wood airplanes and epoxy glues is to not paint them a dark
color.


W. Kern Hendricks
System Three Resins, Inc.
Technical Support: 206/782-0818
FAX: 206/782-4426
Orders Only: 800/333-5514
P.O. Box 70436
Seattle, WA 98107
e-mail: [email protected]

[N96337]

Re: where to buy spars

Alwaysoar, yes, you are correct, they have to meet the specs to be legal. They don't have to be "certified" as such, because you do that yourself on the owner produced part. The non-aircraft sources aren't able to supply "certified" material, but if you show and tell them what you want, they are usually happy to help you comply. I bought 6 blanks from Flounder Bay, and they cut them right there, and I actually refused one, because it had a small knot, and I didn't want any knots, but they were fine with that, and cut me one more to replace it. Like was said, AC43.13 has info on the specs. The blanks I got were well within the limits, but I paid a little more for them, yet not as much as from Aircraft Spruce or a supplier like that.
Acroeric, I have seen that info before, and like I said, there's alot of planes running around with that glue.. I know of 3 here in the area... but it's still not legal on a certified airplane, like you said. I had built up a set of Tcraft spars and used T-88 on the reinforcing plates, when I learned about that aspect of epoxy, so I decided to remove the plates.... all I did was take a hair dryer and my fingers, and the plates came right off!!! Didn't take long at all... made a believer out of me! I actually don't see why nobody wants to use resourcinol.. it's certainly not any more hassle in my eyes, and it's legal and safe in all aspects... maybe I'm missing something. I have told people that if their airplane came in my shop for an annual, and I find epoxy glue in the wings, it's not going to leave with it there.
To each their own.
John H.

[alwaysoar]

Re: where to buy spars

Wouldn't it be acceptable to expoxy and nail?

[N96337]

Re: where to buy spars

On an experimental aircraft, yes. On a certificated aircraft, no. Again, I can't help but wonder why you'd want to use epoxy? I've used resorcinol for 25+ years, and don't see any great advantage of the others. I'm open to all opinions and like I said, maybe I'm missing something?
John H.

[high time cub]

Re: where to buy spars

For victorbravo: https://www.seqair.com/skunkworks/Gl.../Aerolite.html

[alwaysoar]

Re: where to buy spars

For Jim: Huh? Do you understand that? You're a musician.

[high time cub]

Re: where to buy spars

Hi Ed! More Mosquito and glues, casein then Aerolite:

http://post.queensu.ca/cgi-bin/listserv/wa?A2=ind0506&L=marhst-l&F=&S=&P=70387

[R. Winger]

Re: where to buy spars

What is the consensus on the plywood doublers out at the strut attach? My spars use mahogony ply, wouldn't a birch aircraft ply be stronger?

[Sloanlow]

Re: where to buy spars

Jason

Both my spars are cracked from the ground loop. I will be needing a set of spars also. Please advise what you find out. If anyone need spars for a clippe dwing let me know.

Currently I have an experienced man here in Marfa that will be building mine. Aircraft spruce sells Spar material but I think the trick is to order the minimum acceptable length and get Aircraft Spruce to ship them by truck, insured. If they are dammaged by the freight co then you should be reimbursed. I'm just rambling here but I think that I'm on track. Someone please argue the point if I'm wrong. I do not want to pursue bad ideas.

Jim

[N96337]

Re: where to buy spars

Last set that I had shipped, we went with Delta Air Freight. I couldn't believe how cheap they were! Ya might want to check that out!
John H.

[gmackay]

Re: where to buy spars

R.Winger,
I asked the same question about the doublers........didn't get much response, but did receive more nod's for birch than mahagony, saying that birch was stronger. I can also add that the Swick plans for the clip-wing call for birch, but I don't have any real drawings for the original wing.

Jim,
can you tell me more about your clip-wing spars? history, age, condition,etc?
Also, I had spars shipped from Aircraft Spruce. They shipped by Fed-Ex , and were damaged. ACS told me to refuse the shipment, they replace the damaged spar and reshipped. It didn't cost me, but I did keep getting a bill for the first. That took a few phone calls to straighten out.

Greg

[mulwyk]

Re: where to buy spars

I got a set of spars shipped from Aircraft Spruce this summer. They shipped them FedEx Ground, strapped between two 3/8" X 6" X 16' pieces of spruce "scrap" and enclosed in a long cardboard box. They arrived in perfect condition. Shipping cost from CA to SD was about $100.

Bob Gustafson