Re: Wing Spars Fairchild 24W40

[michael_thomas8]

'
I have three sets of original wing spars (front and back x 3) for my 1940 fairchild 24w.  All are original but are 75 years old.  They appear to be in good shape but i dont know enough about wood wings to determine if i should use them or replace them with new.  Does anyone know an expert in wood wings that could tell me if they are useable or if they should go to the burn pile.  They have darkened considerably with age, dont aprear to have any major cracks and are straight. How do i know if there is dry rot or anything else that would render them unserviceable?


Thanks,
Mike

660-631-3270

'

[Hans Friedebach]

'







Michael,
Age alone does no harm to wood unless the storage conditions were hostile.
 
Sounds like you are near Warrensburg, MO – not that far from that vintage airplane hotbed called Creve Coeur. Plenty of expertise there.
Also The AAA Chapter Northwest Missouri, Excelsior Springs airport 3EX  - their Pancake breakfast is July 11th
http://www.thenew3ex.com/
Also   http://www.thenew3ex.com/northwest-mo-aaa-chapter/
 
 
How about the A&P / IA you will be working with on your restoration? You should be working with someone who has the qualifications and willingness to sign off
the 337 for the wood wings they will be used on.
 
Curious: were these spars were salvaged from original wings or if they are NOS spare parts made by the factory or if they are raw, un-machined and undrilled spar
stock?
 
Good luck
Hans
 


From: fairchildclub@yahoogroups.com [mailto:fairchildclub@yahoogroups.com]

Sent: Thursday, July 02, 2015 11:48 PM
To: fairchildclub@yahoogroups.com
Subject: [fairchildclub] Wing Spars Fairchild 24W40


 
 




I have three sets of original wing spars (front and back x 3) for my 1940 fairchild 24w.  All are original but are 75 years old.  They appear to be in good shape but i dont know enough about wood wings to determine if i should use them or replace them with
new.  Does anyone know an expert in wood wings that could tell me if they are useable or if they should go to the burn pile.  They have darkened considerably with age, dont aprear to have any major cracks and are straight. How do i know if there is dry rot
or anything else that would render them unserviceable?

 

Thanks,

Mike

660-631-3270

 






'

[Michael Thomas]

'Hans,
Thank you for your help.  The spars that i have are the original spars from one wing of my airplane and salvaged spars from both wings of another so unfortunately they are not new old stock.  The  A&P IA that i am working with has not had an opportunity to look at them yet but he told me that he has not had a lot of experience with wood wings and recommended that i see if there is a subject matter expert that could give me a better answer.  It is my understanding that the airplane that i have was disassembled in 1961 after it was ground looped and the parts have been stored since then.
I live in Marshall so i am only about 50 minutes from Warrensburg.  Creve Coeur is about 2 1/2 hours east.
Thanks Mike
Sent from my iPad

On Jul 3, 2015, at 07:38, Hans Friedebach hans@tsoproducts.com [fairchildclub] wrote:

 
Michael, Age alone does no harm to wood unless the storage conditions were hostile.   Sounds like you are near Warrensburg, MO – not that far from that vintage airplane hotbed called Creve Coeur. Plenty of expertise there. Also The AAA Chapter Northwest Missouri, Excelsior Springs airport 3EX  - their Pancake breakfast is July 11th http://www.thenew3ex.com/ Also   http://www.thenew3ex.com/northwest-mo-aaa-chapter/     How about the A&P / IA you will be working with on your restoration? You should be working with someone who has the qualifications and willingness to sign off the 337 for the wood wings they will be used on.   Curious: were these spars were salvaged from original wings or if they are NOS spare parts made by the factory or if they are raw, un-machined and undrilled spar stock?   Good luck Hans   From: fairchildclub@yahoogroups.com [fairchildclub@yahoogroups.com]
Sent: Thursday, July 02, 2015 11:48 PM
To: fairchildclub@yahoogroups.com
Subject: [fairchildclub] Wing Spars Fairchild 24W40    
I have three sets of original wing spars (front and back x 3) for my 1940 fairchild 24w.  All are original but are 75 years old.  They appear to be in good shape but i dont know enough about wood wings to determine if i should use them or replace them with new.  Does anyone know an expert in wood wings that could tell me if they are useable or if they should go to the burn pile.  They have darkened considerably with age, dont aprear to have any major cracks and are straight. How do i know if there is dry rot or anything else that would render them unserviceable?
 
Thanks,
Mike
660-631-3270
 
'

[Hans Friedebach]

'Mike

You might enjoy and find the network connections useful in Excelsior springs, only a little over an hour drive.

You are well advised to find someone familiar with “used and abused” spars. Groundloop cracks can be difficult to detect visually in an otherwise perfect looking spar. I have been able to find them at times only by having someone apply an up-load on the wing while examining the spar particularly near the through holes where the struts attach to the spar. Under load an otherwise invisible crack opens up enough to see it.



FAA 8083-31 AVIATION MAINTENANCE Technician HANDBOOK – Airframe Vol 1 is available, like the entire series, as a free download to have on your laptop or eReader in the shop.

https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/



See Chapter 6 Aircraft Wood and Structural Repair

This series of relatively recent publications is an excellent resource. Hard copies are sold by ASA

http://www.asa2fly.com/AMT-C33.aspx



Let me know how it turns out

Hans

952 270-4892



From: fairchildclub@yahoogroups.com [mailto:fairchildclub@yahoogroups.com]

Sent: Friday, July 03, 2015 11:53 AM

To: fairchildclub@yahoogroups.com

Subject: Re: [fairchildclub] Wing Spars Fairchild 24W40





Hans,



Thank you for your help. The spars that i have are the original spars from one wing of my airplane and salvaged spars from both wings of another so unfortunately they are not new old stock. The A&P IA that i am working with has not had an opportunity to look at them yet but he told me that he has not had a lot of experience with wood wings and recommended that i see if there is a subject matter expert that could give me a better answer. It is my understanding that the airplane that i have was disassembled in 1961 after it was ground looped and the parts have been stored since then.



I live in Marshall so i am only about 50 minutes from Warrensburg. Creve Coeur is about 2 1/2 hours east.



Thanks

Mike

Sent from my iPad

On Jul 3, 2015, at 07:38, Hans Friedebach hans@tsoproducts.com [fairchildclub] wrote:



Michael,

Age alone does no harm to wood unless the storage conditions were hostile.



Sounds like you are near Warrensburg, MO – not that far from that vintage airplane hotbed called Creve Coeur. Plenty of expertise there.

Also The AAA Chapter Northwest Missouri, Excelsior Springs airport 3EX - their Pancake breakfast is July 11th http://www.thenew3ex.com/

Also http://www.thenew3ex.com/northwest-mo-aaa-chapter/





How about the A&P / IA you will be working with on your restoration? You should be working with someone who has the qualifications and willingness to sign off the 337 for the wood wings they will be used on.



Curious: were these spars were salvaged from original wings or if they are NOS spare parts made by the factory or if they are raw, un-machined and undrilled spar stock?



Good luck

Hans



From: fairchildclub@yahoogroups.com [mailto:fairchildclub@yahoogroups.com]

Sent: Thursday, July 02, 2015 11:48 PM

To: fairchildclub@yahoogroups.com

Subject: [fairchildclub] Wing Spars Fairchild 24W40







I have three sets of original wing spars (front and back x 3) for my 1940 fairchild 24w. All are original but are 75 years old. They appear to be in good shape but i dont know enough about wood wings to determine if i should use them or replace them with new. Does anyone know an expert in wood wings that could tell me if they are useable or if they should go to the burn pile. They have darkened considerably with age, dont aprear to have any major cracks and are straight. How do i know if there is dry rot or anything else that would render them unserviceable?







Thanks,



Mike



660-631-3270









[Non-text portions of this message have been removed]

'

[Michael Thomas]

'Hans,

Again thank you for all the help. I will check the resources you have given me.

Mike

Sent from my iPad

> On Jul 3, 2015, at 11:58, Hans Friedebach hans@tsoproducts.com [fairchildclub] wrote:
>
> ASA

'

[Ranchaero Wing Shop]

' Mike,

One thing I would keep in mind about old wood is that it sometimes gets too dry and becomes brittle. I have no scientific data to back this up or to determine any quantitative values but intuitively feel that wood can become excessively dry and brittle with age, losing strength and resilience to bending. I don't know how you would determine this other than through destructive testing. For my own purposes, I observe that wood has a certain resonant sound when handled that I associate with dryness and brittleness. There's nothing scientific about this - just my intuition and experience. Also, this old wood seems very light in weight. I would guess because it has such a low moisture content. Personally, I wouldn't trust old spars that had these qualities I intuitively associate with brittleness from age drying even though there was no visible problem. The local climate where the wood lived is likely a factor. Aside from dry rot, I believe that seasonal extremes of very dry to very damp humidity take a toll on the cellular structure of wood. Even though there may be no visible damage, the damage is perhaps on a cellular level. If never stressed, this wood might last a long time and look fine, but under stress might fail through brittleness.
 
Personally, I'm quick to replace spars where there's any doubt since they are so critical. Spar failures are usually in old wood. A few hundred dollars is a worthwhile investment where spars are concerned. I could be wrong so do your research. This is all very intuitive for me having worked with spruce for many years with spruce piano soundboards and spruce wooden aircraft. It's very difficult to scientifically explore these questions, though there is probably data somewhere if you can  take the time to look for it.

David



On 7/3/2015 8:53 AM, Michael Thomas michael_thomas8@yahoo.com [fairchildclub] wrote:

  Hans,
Thank you for your help.  The spars that i have are the original spars from one wing of my airplane and salvaged spars from both wings of another so unfortunately they are not new old stock.  The  A&P IA that i am working with has not had an opportunity to look at them yet but he told me that he has not had a lot of experience with wood wings and recommended that i see if there is a subject matter expert that could give me a better answer.  It is my understanding that the airplane that i have was disassembled in 1961 after it was ground looped and the parts have been stored since then.
I live in Marshall so i am only about 50 minutes from Warrensburg.  Creve Coeur is about 2 1/2 hours east.
Thanks  Mike
Sent from my iPad
On Jul 3, 2015, at 07:38, Hans Friedebach hans@tsoproducts.com [fairchildclub] wrote:

 
Michael, Age alone does no harm to wood unless the storage conditions were hostile.   Sounds like you are near Warrensburg, MO – not that far from that vintage airplane hotbed called Creve Coeur. Plenty of expertise there. Also The AAA Chapter Northwest Missouri, Excelsior Springs airport 3EX  - their Pancake breakfast is July 11th http://www.thenew3ex.com/ Also   http://www.thenew3ex.com/northwest-mo-aaa-chapter/     How about the A&P / IA you will be working with on your restoration? You should be working with someone who has the qualifications and willingness to sign off the 337 for the wood wings they will be used on.   Curious: were these spars were salvaged from original wings or if they are NOS spare parts made by the factory or if they are raw, un-machined and undrilled spar stock?   Good luck Hans   From: fairchildclub@yahoogroups.com [fairchildclub@yahoogroups.com]
Sent: Thursday, July 02, 2015 11:48 PM
To: fairchildclub@yahoogroups.com
Subject: [fairchildclub] Wing Spars Fairchild 24W40    
I have three sets of original wing spars (front and back x 3) for my 1940 fairchild 24w.  All are original but are 75 years old.  They appear to be in good shape but i dont know enough about wood wings to determine if i should use them or replace them with new.  Does anyone know an expert in wood wings that could tell me if they are useable or if they should go to the burn pile.  They have darkened considerably with age, dont aprear to have any major cracks and are straight. How do i know if there is dry rot or anything else that would render them unserviceable?
 
Thanks,
Mike
660-631-3270
 

This email has been checked for viruses by Avast antivirus software.
www.avast.com
'

[Andrew Budek-Schmeisser]

'I used to teach timber design in structural engineering, and yes, it
all depends on storage conditions. Wood is very dynamic in its
response to moisture and will adjust to ambient conditions. If there's
no apparent damage, one other criterion I'd ue is to feel the 'face'
surface. If it's 'ribby', that is, the grain lines are prominent,
don't use them.

Also, check the ends in good light, using a magnifying glass. That's
where cracks will start.

Also pay attention to any plates glued to the spars, and to bolt holes.

I once built a new centersection for a KR-34 when I lived near Austin,
and then moved to Lubbock, which is significantly drier. Over a few
months the wood shrank under the end fittings and cracked from two
bolt holes to the spar ends. The cracks were small, but clearly
visible in good light. (I was able to fix them with plates, without
replacing the spars, but it was a pain.)

If you have any doubts, you can sell them to a local homebuilder for
use as rib or fairing stock. If they look good, even though you may
not be comfortable with them a spars, they will yield a decent amount
of 1/4 sq. rib pieces.

On 7/3/15, Ranchaero Wing Shop david@ranchaerowingshop.com
[fairchildclub] wrote:

> Mike,
>
> One thing I would keep in mind about old wood is that it sometimes gets
> too dry and becomes brittle. I have no scientific data to back this up
> or to determine any quantitative values but intuitively feel that wood
> can become excessively dry and brittle with age, losing strength and
> resilience to bending. I don't know how you would determine this other
> than through destructive testing. For my own purposes, I observe that
> wood has a certain resonant sound when handled that I associate with
> dryness and brittleness. There's nothing scientific about this - just my
> intuition and experience. Also, this old wood seems very light in
> weight. I would guess because it has such a low moisture content.
> Personally, I wouldn't trust old spars that had these qualities I
> intuitively associate with brittleness from age drying even though there
> was no visible problem. The local climate where the wood lived is likely
> a factor. Aside from dry rot, I believe that seasonal extremes of very
> dry to very damp humidity take a toll on the cellular structure of wood.
> Even though there may be no visible damage, the damage is perhaps on a
> cellular level. If never stressed, this wood might last a long time and
> look fine, but under stress might fail through brittleness.
>
> Personally, I'm quick to replace spars where there's any doubt since
> they are so critical. Spar failures are usually in old wood. A few
> hundred dollars is a worthwhile investment where spars are concerned. I
> could be wrong so do your research. This is all very intuitive for me
> having worked with spruce for many years with spruce piano soundboards
> and spruce wooden aircraft. It's very difficult to scientifically
> explore these questions, though there is probably data somewhere if you
> can take the time to look for it.
>
> David
>
>
>
> On 7/3/2015 8:53 AM, Michael Thomas michael_thomas8@yahoo.com
> [fairchildclub] wrote:
>> Hans,
>>
>> Thank you for your help. The spars that i have are the original spars
>> from one wing of my airplane and salvaged spars from both wings of
>> another so unfortunately they are not new old stock. The A&P IA that
>> i am working with has not had an opportunity to look at them yet but
>> he told me that he has not had a lot of experience with wood wings and
>> recommended that i see if there is a subject matter expert that could
>> give me a better answer. It is my understanding that the airplane
>> that i have was disassembled in 1961 after it was ground looped and
>> the parts have been stored since then.
>>
>> I live in Marshall so i am only about 50 minutes from Warrensburg.
>> Creve Coeur is about 2 1/2 hours east.
>>
>> Thanks
>> Mike
>> Sent from my iPad
>>
>> On Jul 3, 2015, at 07:38, Hans Friedebach hans@tsoproducts.com
>> [fairchildclub]
>>
>> wrote:
>>
>>> Michael,
>>>
>>> Age alone does no harm to wood unless the storage conditions were
>>> hostile.
>>>
>>> Sounds like you are near Warrensburg, MO – not that far from that
>>> vintage airplane hotbed called Creve Coeur. Plenty of expertise there.
>>>
>>> Also The AAA Chapter Northwest Missouri, Excelsior Springs airport
>>> 3EX - their Pancake breakfast is July 11^th http://www.thenew3ex.com/
>>>
>>> Also http://www.thenew3ex.com/northwest-mo-aaa-chapter/
>>>
>>> How about the A&P / IA you will be working with on your restoration?
>>> You should be working with someone who has the qualifications and
>>> willingness to sign off the 337 for the wood wings they will be used on.
>>>
>>> Curious: were these spars were salvaged from original wings or if
>>> they are NOS spare parts made by the factory or if they are raw,
>>> un-machined and undrilled spar stock?
>>>
>>> Good luck
>>>
>>> Hans
>>>
>>> *From:*fairchildclub@yahoogroups.com
>>>
>>> [mailto:fairchildclub@yahoogroups.com]
>>> *Sent:* Thursday, July 02, 2015 11:48 PM
>>> *To:* fairchildclub@yahoogroups.com
>>>
>>> *Subject:* [fairchildclub] Wing Spars Fairchild 24W40
>>>
>>> I have three sets of original wing spars (front and back x 3) for my
>>> 1940 fairchild 24w. All are original but are 75 years old. They
>>> appear to be in good shape but i dont know enough about wood wings to
>>> determine if i should use them or replace them with new. Does anyone
>>> know an expert in wood wings that could tell me if they are useable
>>> or if they should go to the burn pile. They have darkened
>>> considerably with age, dont aprear to have any major cracks and are
>>> straight. How do i know if there is dry rot or anything else that
>>> would render them unserviceable?
>>>
>>> Thanks,
>>>
>>> Mike
>>>
>>> 660-631-3270
>>>
>>
>
>
>
> ---
> This email has been checked for viruses by Avast antivirus software.
> https://www.avast.com/antivirus
>

'

[Hans Friedebach]

'







The ultimate resource and scientific data:
ANC-19 Wood Aircraft Inspection and Fabrication by the Forest Products Laboratory and the Aircraft Committee of the Munitions Board  1951 (online and  in the
public domain)
 
WOOD HANDBOOK, Wood as an Engineering Material; Forest Products Laboratory, General Technical Report FPL-GTR-113
 
Moisture content regardless of age stabilizes at some level depending on the environment somewhere not too far from 10%. Actual MC can easily be measured using
relatively inexpensive equipment like the Lignomat Mini-Ligno DX/c or Delmhorst J-2000
 
Hans
 


From: fairchildclub@yahoogroups.com [mailto:fairchildclub@yahoogroups.com]

Sent: Friday, July 03, 2015 2:17 PM
To: fairchildclub@yahoogroups.com
Subject: Re: [fairchildclub] Wing Spars Fairchild 24W40


 
 




Mike,

One thing I would keep in mind about old wood is that it sometimes gets too dry and becomes brittle. I have no scientific data to back this up or to determine any quantitative values but intuitively feel that wood can become excessively dry and brittle with
age, losing strength and resilience to bending. I don't know how you would determine this other than through destructive testing. For my own purposes, I observe that wood has a certain resonant sound when handled that I associate with dryness and brittleness.
There's nothing scientific about this - just my intuition and experience. Also, this old wood seems very light in weight. I would guess because it has such a low moisture content. Personally, I wouldn't trust old spars that had these qualities I intuitively
associate with brittleness from age drying even though there was no visible problem. The local climate where the wood lived is likely a factor. Aside from dry rot, I believe that seasonal extremes of very dry to very damp humidity take a toll on the cellular
structure of wood. Even though there may be no visible damage, the damage is perhaps on a cellular level. If never stressed, this wood might last a long time and look fine, but under stress might fail through brittleness.
 
Personally, I'm quick to replace spars where there's any doubt since they are so critical. Spar failures are usually in old wood. A few hundred dollars is a worthwhile investment where spars are concerned. I could be wrong so do your research. This is all very
intuitive for me having worked with spruce for many years with spruce piano soundboards and spruce wooden aircraft. It's very difficult to scientifically explore these questions, though there is probably data somewhere if you can  take the time to look for
it.

David

On 7/3/2015 8:53 AM, Michael Thomas michael_thomas8@yahoo.com [fairchildclub] wrote:

 


Hans,


 


Thank you for your help.  The spars that i have are the original spars from one wing of my airplane and salvaged spars from both wings of another so unfortunately they are not new old stock.  The  A&P IA that i am working with has not had
an opportunity to look at them yet but he told me that he has not had a lot of experience with wood wings and recommended that i see if there is a subject matter expert that could give me a better answer.  It is my understanding that the airplane that i have
was disassembled in 1961 after it was ground looped and the parts have been stored since then.


 


I live in Marshall so i am only about 50 minutes from Warrensburg.  Creve Coeur is about 2 1/2 hours east.


 


Thanks 


Mike
Sent from my iPad



On Jul 3, 2015, at 07:38, Hans Friedebach hans@tsoproducts.com [fairchildclub] wrote:



 


Michael,
Age alone does no harm to wood unless the storage conditions were hostile.
 
Sounds like you are near Warrensburg, MO – not that far from that vintage airplane hotbed called Creve
Coeur. Plenty of expertise there.
Also The AAA Chapter Northwest Missouri, Excelsior Springs airport 3EX  - their Pancake breakfast is
July 11th http://www.thenew3ex.com/
Also   http://www.thenew3ex.com/northwest-mo-aaa-chapter/
 
 
How about the A&P / IA you will be working with on your restoration? You should be working with someone
who has the qualifications and willingness to sign off the 337 for the wood wings they will be used on.
 
Curious: were these spars were salvaged from original wings or if they are NOS spare parts made by
the factory or if they are raw, un-machined and undrilled spar stock?
 
Good luck
Hans
 


From:
fairchildclub@yahoogroups.com [fairchildclub@yahoogroups.com]

Sent: Thursday, July 02, 2015 11:48 PM
To: fairchildclub@yahoogroups.com
Subject: [fairchildclub] Wing Spars Fairchild 24W40


 
 





I have three sets of original wing spars (front and back x 3) for my 1940 fairchild 24w.  All are original but are 75 years old.  They appear to be in good shape but i dont know enough about wood wings to determine if i should use them or replace them with
new.  Does anyone know an expert in wood wings that could tell me if they are useable or if they should go to the burn pile.  They have darkened considerably with age, dont aprear to have any major cracks and are straight. How do i know if there is dry rot
or anything else that would render them unserviceable?

 

Thanks,

Mike

660-631-3270

 























This email has been checked for viruses by Avast antivirus software.

www.avast.com




 







'

[Michael Thomas]

'Thanks David.  Good food for thought as I begin this project.

Sent from my iPad

On Jul 3, 2015, at 13:17, Ranchaero Wing Shop david@ranchaerowingshop.com [fairchildclub] wrote:

 
Mike,

One thing I would keep in mind about old wood is that it sometimes gets too dry and becomes brittle. I have no scientific data to back this up or to determine any quantitative values but intuitively feel that wood can become excessively dry and brittle with age, losing strength and resilience to bending. I don't know how you would determine this other than through destructive testing. For my own purposes, I observe that wood has a certain resonant sound when handled that I associate with dryness and brittleness. There's nothing scientific about this - just my intuition and experience. Also, this old wood seems very light in weight. I would guess because it has such a low moisture content. Personally, I wouldn't trust old spars that had these qualities I intuitively associate with brittleness from age drying even though there was no visible problem. The local climate where the wood lived is likely a factor. Aside from dry rot, I believe that seasonal extremes of very dry to very damp humidity take a toll on the cellular structure of wood. Even though there may be no visible damage, the damage is perhaps on a cellular level. If never stressed, this wood might last a long time and look fine, but under stress might fail through brittleness.
 
Personally, I'm quick to replace spars where there's any doubt since they are so critical. Spar failures are usually in old wood. A few hundred dollars is a worthwhile investment where spars are concerned. I could be wrong so do your research. This is all very intuitive for me having worked with spruce for many years with spruce piano soundboards and spruce wooden aircraft. It's very difficult to scientifically explore these questions, though there is probably data somewhere if you can  take the time to look for it.

David



On 7/3/2015 8:53 AM, Michael Thomas michael_thomas8@yahoo.com [fairchildclub] wrote:
  Hans,
Thank you for your help.  The spars that i have are the original spars from one wing of my airplane and salvaged spars from both wings of another so unfortunately they are not new old stock.  The  A&P IA that i am working with has not had an opportunity to look at them yet but he told me that he has not had a lot of experience with wood wings and recommended that i see if there is a subject matter expert that could give me a better answer.  It is my understanding that the airplane that i have was disassembled in 1961 after it was ground looped and the parts have been stored since then.
I live in Marshall so i am only about 50 minutes from Warrensburg.  Creve Coeur is about 2 1/2 hours east.
Thanks  Mike
Sent from my iPad
On Jul 3, 2015, at 07:38, Hans Friedebach hans@tsoproducts.comhans@tsoproducts.com [fairchildclub] wrote:

 
Michael, Age alone does no harm to wood unless the storage conditions were hostile.   Sounds like you are near Warrensburg, MO – not that far from that vintage airplane hotbed called Creve Coeur. Plenty of expertise there. Also The AAA Chapter Northwest Missouri, Excelsior Springs airport 3EX  - their Pancake breakfast is July 11th http://www.thenew3ex.com/ Also   http://www.thenew3ex.com/northwest-mo-aaa-chapter/     How about the A&P / IA you will be working with on your restoration? You should be working with someone who has the qualifications and willingness to sign off the 337 for the wood wings they will be used on.   Curious: were these spars were salvaged from original wings or if they are NOS spare parts made by the factory or if they are raw, un-machined and undrilled spar stock?   Good luck Hans   From: fairchildclub@yahoogroups.comfairchildclub@yahoogroups.com [fairchildclub@yahoogroups.com]
Sent: Thursday, July 02, 2015 11:48 PM
To: fairchildclub@yahoogroups.com
Subject: [fairchildclub] Wing Spars Fairchild 24W40    
I have three sets of original wing spars (front and back x 3) for my 1940 fairchild 24w.  All are original but are 75 years old.  They appear to be in good shape but i dont know enough about wood wings to determine if i should use them or replace them with new.  Does anyone know an expert in wood wings that could tell me if they are useable or if they should go to the burn pile.  They have darkened considerably with age, dont aprear to have any major cracks and are straight. How do i know if there is dry rot or anything else that would render them unserviceable?
 
Thanks,
Mike
660-631-3270
 


This email has been checked for viruses by Avast antivirus software.
www.avast.com

'

[Michael Thomas]

'Wow, great information from all of you.  Thanks Andrew ,David and Hans.
Sent from my iPad

On Jul 3, 2015, at 13:30, Andrew Budek-Schmeisser tempusfugit02@gmail.com [fairchildclub] wrote:

 
I used to teach timber design in structural engineering, and yes, it
all depends on storage conditions. Wood is very dynamic in its
response to moisture and will adjust to ambient conditions. If there's
no apparent damage, one other criterion I'd ue is to feel the 'face'
surface. If it's 'ribby', that is, the grain lines are prominent,
don't use them.

Also, check the ends in good light, using a magnifying glass. That's
where cracks will start.

Also pay attention to any plates glued to the spars, and to bolt holes.

I once built a new centersection for a KR-34 when I lived near Austin,
and then moved to Lubbock, which is significantly drier. Over a few
months the wood shrank under the end fittings and cracked from two
bolt holes to the spar ends. The cracks were small, but clearly
visible in good light. (I was able to fix them with plates, without
replacing the spars, but it was a pain.)

If you have any doubts, you can sell them to a local homebuilder for
use as rib or fairing stock. If they look good, even though you may
not be comfortable with them a spars, they will yield a decent amount
of 1/4 sq. rib pieces.

On 7/3/15, Ranchaero Wing Shop david@ranchaerowingshop.com
[fairchildclub] wrote:
> Mike,
>
> One thing I would keep in mind about old wood is that it sometimes gets
> too dry and becomes brittle. I have no scientific data to back this up
> or to determine any quantitative values but intuitively feel that wood
> can become excessively dry and brittle with age, losing strength and
> resilience to bending. I don't know how you would determine this other
> than through destructive testing. For my own purposes, I observe that
> wood has a certain resonant sound when handled that I associate with
> dryness and brittleness. There's nothing scientific about this - just my
> intuition and experience. Also, this old wood seems very light in
> weight. I would guess because it has such a low moisture content.
> Personally, I wouldn't trust old spars that had these qualities I
> intuitively associate with brittleness from age drying even though there
> was no visible problem. The local climate where the wood lived is likely
> a factor. Aside from dry rot, I believe that seasonal extremes of very
> dry to very damp humidity take a toll on the cellular structure of wood.
> Even though there may be no visible damage, the damage is perhaps on a
> cellular level. If never stressed, this wood might last a long time and
> look fine, but under stress might fail through brittleness.
>
> Personally, I'm quick to replace spars where there's any doubt since
> they are so critical. Spar failures are usually in old wood. A few
> hundred dollars is a worthwhile investment where spars are concerned. I
> could be wrong so do your research. This is all very intuitive for me
> having worked with spruce for many years with spruce piano soundboards
> and spruce wooden aircraft. It's very difficult to scientifically
> explore these questions, though there is probably data somewhere if you
> can take the time to look for it.
>
> David
>
>
>
> On 7/3/2015 8:53 AM, Michael Thomas michael_thomas8@yahoo.com
> [fairchildclub] wrote:
>> Hans,
>>
>> Thank you for your help. The spars that i have are the original spars
>> from one wing of my airplane and salvaged spars from both wings of
>> another so unfortunately they are not new old stock. The A&P IA that
>> i am working with has not had an opportunity to look at them yet but
>> he told me that he has not had a lot of experience with wood wings and
>> recommended that i see if there is a subject matter expert that could
>> give me a better answer. It is my understanding that the airplane
>> that i have was disassembled in 1961 after it was ground looped and
>> the parts have been stored since then.
>>
>> I live in Marshall so i am only about 50 minutes from Warrensburg.
>> Creve Coeur is about 2 1/2 hours east.
>>
>> Thanks
>> Mike
>> Sent from my iPad
>>
>> On Jul 3, 2015, at 07:38, Hans Friedebach hans@tsoproducts.com
>> [fairchildclub]
>>
>> wrote:
>>
>>> Michael,
>>>
>>> Age alone does no harm to wood unless the storage conditions were
>>> hostile.
>>>
>>> Sounds like you are near Warrensburg, MO – not that far from that
>>> vintage airplane hotbed called Creve Coeur. Plenty of expertise there.
>>>
>>> Also The AAA Chapter Northwest Missouri, Excelsior Springs airport
>>> 3EX - their Pancake breakfast is July 11^th http://www.thenew3ex.com/
>>>
>>> Also http://www.thenew3ex.com/northwest-mo-aaa-chapter/
>>>
>>> How about the A&P / IA you will be working with on your restoration?
>>> You should be working with someone who has the qualifications and
>>> willingness to sign off the 337 for the wood wings they will be used on.
>>>
>>> Curious: were these spars were salvaged from original wings or if
>>> they are NOS spare parts made by the factory or if they are raw,
>>> un-machined and undrilled spar stock?
>>>
>>> Good luck
>>>
>>> Hans
>>>
>>> *From:*fairchildclub@yahoogroups.com
>>>
>>> [fairchildclub@yahoogroups.com]
>>> *Sent:* Thursday, July 02, 2015 11:48 PM
>>> *To:* fairchildclub@yahoogroups.com
>>>
>>> *Subject:* [fairchildclub] Wing Spars Fairchild 24W40
>>>
>>> I have three sets of original wing spars (front and back x 3) for my
>>> 1940 fairchild 24w. All are original but are 75 years old. They
>>> appear to be in good shape but i dont know enough about wood wings to
>>> determine if i should use them or replace them with new. Does anyone
>>> know an expert in wood wings that could tell me if they are useable
>>> or if they should go to the burn pile. They have darkened
>>> considerably with age, dont aprear to have any major cracks and are
>>> straight. How do i know if there is dry rot or anything else that
>>> would render them unserviceable?
>>>
>>> Thanks,
>>>
>>> Mike
>>>
>>> 660-631-3270
>>>
>>
>
>
>
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