[f-AA] Cracked Spar Mystery

[Ryan]

In April, a new mechanic was doing my annual on my Champ and he discovered a 1.5 ft creek in my right main spar close to the fuselage. It follows the grain of the wood and is only visible in the front side of the spar.  I thought the worst at first as rebuilding my wings is not in my budget.  I discussed a few options with Carl and began to really wish I were closer to Texas.  I took my plane back to its hangar while waiting to decide what to do.  Two weeks ago, a friend's mechanic wanted to take a quick look and made an interesting observation: there is varnish in the crack.  He wasn't able to scope the whole thing, but what was visible at the inspection hole had varnish in the crack.  This brings up the possibility that the imperfection has been in the wood since it was installed in 1976.  My plan now is to get a ferry permit and take it to a nearby place in South Dakota that specializes in Champs and Cubs.  The plan is to investigate the crack more closely and probably remove the fabric from the affected area and sand the spar to see how deep it goes.  If it is only on the surface, I'll be in good shape.


Anybody here have any ideas as to alternative proceedings?


-Ryan

[Jerry Eichenberger]

Replacing the spar isn’t as big, nor as expensive, a deal as you may fear.

Personally, I’d replace it right where it now sits, assuming your mechanic is skilled at wood and fabric work.

I replaced a spar in a wing about 2 years ago due to damage from a renter, and was surprised how relatively easy it was.  I didn’t do the work myself; my mechanic did.

Jerry E.

[Paul Anton]

Get a good wood guy to look at it. If it is indeed a crack I would consider pulling the wing and transporting it rather than flying it.

[Ryan]

$12,000 was the estimate I got to replace the spar and recover both wings.

---

From: JEiche...@ehlawyers.com
To: aer...@westmont.edu
Date: Tue, 1 Jul 2014 22:14:57 +0000
Subject: Re: [f-AA] Cracked Spar Mystery

_______________________________________________ Aeronca mailing list Aer...@westmont.edu http://mail.westmont.edu/mailman/listinfo/aeronca

[Jerry Eichenberger]

Ryan –

Another thought is to open the wing and take a really good look at the spar.  If in fact it is OK, then you only have a fabric repair to do, and you can sleep at night and fly your plane with confidence.

Jerry E.

 

From: aeronca...@westmont.edu [mailto:aeronca...@westmont.edu] On Behalf Of Jerry Eichenberger
Sent: Tuesday, July 01, 2014 6:15 PM
To: aer...@westmont.edu
Subject: Re: [f-AA] Cracked Spar Mystery

 

Replacing the spar isn’t as big, nor as expensive, a deal as you may fear.

[Jerry Eichenberger]

Why recover both wings to replace one spar?  Or, if you are able, recover the one wing yourself, after a mechanic makes the internal repairs.  I am not a mechanic, and have very limited mechanical skills, but even I have recovered a few wings.

[Ryan]

That's my hope, Jerry.

---

From: JEiche...@ehlawyers.com
To: aer...@westmont.edu

Date: Tue, 1 Jul 2014 22:18:21 +0000

Subject: Re: [f-AA] Cracked Spar Mystery

Ryan –

Another thought is to open the wing and take a really good look at the spar.  If in fact it is OK, then you only have a fabric repair to do, and you can sleep at night and fly your plane with confidence.

Jerry E.

 

From: aeronca...@westmont.edu [mailto:aeronca...@westmont.edu] On Behalf Of Jerry Eichenberger
Sent: Tuesday, July 01, 2014 6:15 PM
To: aer...@westmont.edu
Subject: Re: [f-AA] Cracked Spar Mystery

 

Replacing the spar isn’t as big, nor as expensive, a deal as you may fear.

Personally, I’d replace it right where it now sits, assuming your mechanic is skilled at wood and fabric work.

I replaced a spar in a wing about 2 years ago due to damage from a renter, and was surprised how relatively easy it was.  I didn’t do the work myself; my mechanic did.

Jerry E.

 

From: aeronca...@westmont.edu [mailto:aeronca...@westmont.edu] On Behalf Of Ryan
Sent: Tuesday, July 01, 2014 6:03 PM
To: aer...@westmont.edu
Subject: [f-AA] Cracked Spar Mystery

 

In April, a new mechanic was doing my annual on my Champ and he discovered a 1.5 ft creek in my right main spar close to the fuselage. It follows the grain of the wood and is only visible in the front side of the spar.  I thought the worst at first as rebuilding my wings is not in my budget.  I discussed a few options with Carl and began to really wish I were closer to Texas.  I took my plane back to its hangar while waiting to decide what to do.  Two weeks ago, a friend's mechanic wanted to take a quick look and made an interesting observation: there is varnish in the crack.  He wasn't able to scope the whole thing, but what was visible at the inspection hole had varnish in the crack.  This brings up the possibility that the imperfection has been in the wood since it was installed in 1976.  My plan now is to get a ferry permit and take it to a nearby place in South Dakota that specializes in Champs and Cubs.  The plan is to investigate the crack more closely and probably remove the fabric from the affected area and sand the spar to see how deep it goes.  If it is only on the surface, I'll be in good shape.


Anybody here have any ideas as to alternative proceedings?


-Ryan

[Jerry Eichenberger]

A skilled fabric guy can open only enough of the fabric to get a look.  And if it is OK, the fabric repair would be minimal.  That’s what we did with my plane; unfortunately the spar had to be replaced.

Of course, it goes without saying that if here is any real doubt, even after looking at it opened up, do replace the spar.

Also, as I said previously, no need to recover the other wing, unless you are a perfectionist who demands that the paint match perfectly.

Even if you are, then do the other wing in a year or two, as the paint won’t fade on the first recover job if your plane is in a hangar.

Good luck,

[Richard Murray]

Don't spend 12,000 for a repair you can do yourself for a fraction of that cost. I'd have to check my invoices but I think I have less than 3000 to recover my wings. Replacing the spar will take a week or less and nails and the cost of a spar from Rainbow will get you back in the air.

mobile from the Galaxy S4

[Mark Peterson]

And I think that Ron has a STC for using screws instead of nails, which would help keep the planes going
strong for decades.    You can replace a wing rib with a screw, but a nail would destroy the spar if you have
to pull it.

---

Date: Wed, 2 Jul 2014 00:20:49 +0100
From: murra...@gmail.com

[Cy Galley]

Why would a nail destroy a spar? A ring shank nail might as they are hard to remove but  regular nails have been used and removed for 90 years.

 

If you have a question on this check with Bill Pancake. 

 

Using a screw will leave a larger hole than an aircraft nail. Rainbow Ron may have an STC but I'll bet you can buy a lot of nail for the cost of the STC and screws. Look in AC 43-13 for guidance

 

If you break a nail when removing, one can always add another by moving it about 1/4" Drill; a new hole and continue on.

 

Cy Galley - Chairman of Emergency Aircraft Repair

A service project of EAA Chapter 75

[dmc...@theinter.com]

Ryan,
Where is the plane now.
Dion Carr
Champ N84746
Geneseo, IL

[dmc...@theinter.com]

Ryan,
I meant to add give me a call at 815-535-3501
Dion

On 2014-07-01 17:03, Ryan wrote:

[Mark Peterson]

ring shank nail

---

From: cga...@mchsi.com
To: aer...@westmont.edu
Date: Tue, 1 Jul 2014 19:32:47 -0500

[Cy Galley]

Until removed a ring shank is fine, BUT it is not an aircraft nail. I know ring shanks have been used but I don't think you can find FAA approval for their use.  Once driven however, it is impossible to tell what shank is used.  Some use ring shanks to replace aircraft nails which have loosened or fallen out.

[Paul Safran]

We had a similar issue with the rear spar at a flap attach point on our Citabria.

 

Champion advice was to sand and wet with denatured alcohol to confirm crack,

versus varnish imperfection. We could not make it "go away".

 

Opted to do both wings and upgrade to metal spars

(it's a float plane too)

 

NOT CHEAP !!!!!!!!!!!

 

just materials, both wings, polytone finish = $2750+

metal spar kit with leading edge = $8900

labor, paid local mechanics, acid wash & alodine all parts = $9000

we stripped and painted all the iron ourselves.

replaced the flap area trailing edge sheetmetal from Champion

 

Good luck, hopefully just an assembly "scratch"

 

Paul
=====================
Paul Safran
Beech N35 ( D-6729)
at 5B2, Saratoga Springs, NY
7GCBC on straight floats at NK17

[Jerry Jackson]

That is not a bad price if you need to pay for labor. You can save a bundle by doing it yourself. You can save another bundle by doing just one wing.

 

Jerry Jackson

San Antonio

[Rainbow Flying Service]

Just to let everyone know I do have an STC to use screws instead of nails. I use #4X1/2" SS sheet metal screws. I charge $100 per airplane for the STC and $10 for 100 screws. My opinion on the crack: A crack that follows along the grain in that area even if it went half way through the spar is not going to appreciably weaken the spar. ro...@qosi.net           -------Original Message-------

From: Mark Peterson Date: 7/1/2014 5:05:26 PM To: The Fearless Aeronca Aviators

FREE Animations for Your Email! Click Here!

[Dan VanderMeer]

Ryan

Bill Pancake spent about 1/2 hour talking about spars during his presentation at Middletown. He made several points relevant to your experience-

-  It is extremely rare for a spar to crack at points away from the wing strut attachment.  And cracks are most always related to incidents where the wing strikes the ground.

-  The original spars were quite often built in the factory from separate pieces of aircraft spruce wood. Pieces shorter than the spar length were spliced together to build a complete spar. These spiced spars are equal to and often stronger than those formed from a single piece of wood. The splice joint is often identified by an  inexperienced AP as a crack.

-  Bill stressed that if an owner is told that the spar is cracked and is not airworthy, always get another opinion from someone with expertise and experience with aircraft wood.

-  It is as important to carefully examine any replacement spar you might purchase if you indeed need to replace the spar  Regardless of the vendor, workmanship can vary and "new" spars are not always up airworthiness standard. (Sorry Ron. He said this, not me.  And your name was not mentioned in this regard.)  So I pass it along as a caution. 

I have some personal experience in rebuilding wings with new spars.  Here are a some cautions-

-  When you remove the wing and disassemble it, be very careful to remove the ribs without damaging the spar or rib. The original nails can be easily removed with a sharpened very small cats paw lever. Rib shank nails yield to this kind of removal but not so easily.  Its tedious work but the ribs are expensive and most can be reused.  The wood from the cracked spar can be saved and used to splice another spare.

 -  In fact, you may find that the crack in your spar is in a place sufficiently distant from the attachment to the fuselage that it can be spliced.  This kind of repair is safe and legal when done according to the regs and done by someone qualified in and equipped for wood working.

-  There is no real rationale for replacing the other spars in you plane if they are still airworthy. The rear spars take very little stress in normal flight and are not likely to need to be replaced.

-  If you buy a new leading edge spar, you will probably find that it has doublers added at the points where stress is greatest. Most of the original ribs can be fit over these doublers but its not easy and you will probably need some replacement ribs. The vendors of the replacement ribs know this and have engineered the ribs accordingly.

-  Buy new front spar attachment fittings.  These do experience stress in flight and are critical to safety.

I generally agree with most of the other comments and suggestions already posted. But...

-  If you do get a ferry permit, I hope you know that it is most likely to be valid for just that one flight to another mechanic.  Once there, you are pretty much committed to leaving the plane there for repair.  Better to take the advice given to remove the wing and just take it for examination.

-  If you do start taking fabric off to get access to the spar for a better inspection, try not to take it from the top of the wing if possible.  Any patch job on the top may not be legal and a bad patch can be very dangerous.

-  Cy may be correct that a ring shank nail is not FAA approved hardware, But I don't know of any spar replaced in this century that doesn't have that type nail used in attaching the ribs. Unless you want to use the STC for screws. I know of instances where Aeroncas have been determined to be un-airworthy because the original nails worked loose and the AP was concerned that the ribs would fail. Go figure...

-  Finally, call Bill Pancake.  He is very approachable and willing to help with advice.

Good luck,

Dan v

[Richard Murray]

Excellent Dan v

[joer...@suddenlink.net]

> In April, a new mechanic was doing my annual on my Champ and he discovered a
> 1.5 ft creek in my right main spar close to the fuselage. It follows the
> grain of the wood and is only visible in the front side of the spar. I
> thought the worst at first as rebuilding my wings is not in my budget. I
> discussed a few options with Carl and began to really wish I were closer to
> Texas. I took my plane back to its hangar while waiting to decide what to
> do. Two weeks ago, a friend's mechanic wanted to take a quick look and made
> an interesting observation: there is varnish in the crack. He wasn't able
> to scope the whole thing, but what was visible at the inspection hole had
> varnish in the crack. This brings up the possibility that the imperfection
> has been in the wood since it was installed in 1976. My plan now is to get
> a ferry permit and take it to a nearby place in South Dakota that
> specializes in Champs and Cubs. The plan is to investigate the crack more
> closely and probably remove the fabric from the affected area and sand the
> spar to see how deep it goes. If it is only on the surface, I'll be in good
> shape.
>
>
>
>
>
> Anybody here have any ideas as to alternative proceedings?
>
>
>
>
>
> -Ryan

It is very difficult to make repair decisions without seeing the actual problem. Even pictures are not as good as the actual eyeball. Before you spend thousands of dollars I would suggest you arm yourself with some knowledge. As the owner of an obsolete aircraft that today's mechanics have little if any experience with you have to accumulate the repair knowledge yourself. But you already know that since you are here asking. AC43.13-1B and AC43.13-2B are available online or you can buy a hard copy from ACS or etc.. Read AC43.13-1B sections 1, 3, and 4. Your focus will be on paragraph "1-44 Spar longitudinal cracks and local damage" and "fig.1-10" in section 4. You can find the same thing in the obsolete CAM 18 (Civil Aeronautics Manual 18) that was appropriate when your airplane was built. Paragraph 18.6013 on page 18 of my copy and figure 7 on page 54. It sounds like this would be your answer according to your description and assuming the crack does not extend under the plate
for the
fuselage attachment fitting.. Should cost a lot less than $12,000. You must learn to navigate through the FARs the CARs and the Advisory Circulars especially 43.13-1A and 2B. It takes an effort to understand the FAA's system and logic but once you make the effort it will save you money and heartache. Oh, and if you decide to do your own maintenance and repairs under the supervision of an A&P consider keeping a log of the date and what you did and how long it took so you can verify the hours and test for your own A&P license when you accumulate the time. jrh