[Shop-talk] Welding a cracked fan Blade

[James F Juhas]

It's supposed to, but I gave some doubts.  NDI was my specialty when I 
was in the Air Force many years ago.  I don't recall ever magnafluxing 
something that thin.  It was usually castings and much heavier pieces.  
I don't know if a sub-surface crack in a steel .060 to .100 inches thick 
would set up a pole that would attract the material.  Or if there would 
be any sub-surface irregularity that will show up that would predict 
failure. 

I solved my doubts with an electric fan.

David Scheidt wrote:
> On Mon, Dec 1, 2008 at 10:25 AM, James F Juhas <james.f.juhas at snet.net> wrote:
>   
>> That is exactly what I would do, and indeed, what I was going to do when
>> my MGA fan lost a blade through my left fender well at 6,000 rpm on the
>> Lightening course at NJMP.  Notwithstanding the fact that I picked up
>> considerable horsepower after I took the fan off, I doubted the wisdom
>> of making the repair after taking a close look at it.  Besides the blade
>> that broke off, another had a partial crack and would have been next to
>> go.  And this was in September, after a close inspection of the fan in
>> August revealed no likely defects.  The moral is to be wary of
>> 50-year-old steel.
>>     
>
> will magnafluxing or the like detect cracks that aren't yet at the surface?
>
>   


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