Re: Aeronca 11AC Chief Project FS

Dan ...

I maintain on an inspection basis a few 11ACs.  I have yet to see one with

that AD spar cracking problem.  It was re****ted a few times to Ok City
under 
their wonderful "tell us about your problems" program and (I'm wild ass 
guessing here) some wet behind the ears history major puke that couldn't 
tell a cotter pin from a diaper pin picked up on it and made it an AD.  It

is, as far as I can tell, not a "tendency" but an abberation that a few of

the Airnockers have suffered.  Not a widespread problem.

On the other hand, a few years ago, I inspected airplane after airplane
with 
cracked spars.  Upon investigation, I found that I had a cracked
inspection 
mirror {;-)


Jim

-- 
"It is the mark of an educated mind to be able to entertain a thought 
without accepting it."
        --Aristotle


<Dan_Thomas_nospam@[EMAIL PROTECTED]
> wrote in message 
news:1b0c91f5-da1f-433a-9f87-214b3ded1f37@[EMAIL PROTECTED]
> On Jun 22, 6:39 pm, "RST Engineering" <j...@[EMAIL PROTECTED]
> wrote:
>>  An 11AC with a possible
>> busted spar isn't a bargain at giveaway prices, much less the asking 
>> price.
>
>     I would expect to replace those spars anyway. The AD 2000-25-02R1
> addresses the tendency of Aeronca spars to crack through the rib nail
> holes as the wood dries out and shrinks across the grain while the
> metal ribs try to prevent it, splitting the spars along the grain. The
> plywood doublers at the spar attach points cause local stiffness that
> forces the wood at the top of the spar at the ends of the doublers to
> suffer compression fractures which extend down through the spar. The
> plywood doubles at the spar butts cover cracks through the spar
> itself, and perhaps those doublers are contributing to stress cracking
> in the same way as the metal ribs.
>    See this: 
>
http://www.tc.gc.ca/civilaviation/certification/continuing/Alert/2001-05.htm
>      Re-sparring isn't cheap, and those aluminum ribs are often
> corroded, too. American Champion sells brand-new all-metal wings with
> or without the fabric. They aren't cheap, either.
>
>        Dan
>
>
>