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December 2015

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Subject:
From:
Mike Fenner <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Mike Fenner <[log in to unmask]>
Date:
Thu, 3 Dec 2015 09:40:56 -0000
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I only have a very broad over view of the situation with Pb free and Airbus
but I believe it was their intention about 6? years -possibly a couple more
- ago to go Pb free. Whether that was for new designs only or was
retrospective (re-engineer all prior Pb containing) I don't know.
In any case whether Pb+ or Pb- it doesn't change the number of times they
seemingly "repaired" the cracked joints. If ground people really did repair
unit every couple of weeks or so instead of pulling it for investigation for
root cause (and presumably looking for the same fault in other units etc,)
then it's entirely possible that the worst case scenario applied: the
maintenance/service people simply touched up/reflowed the joint and put unit
back in service. Its hard to see how they could do that so many times though
without causing more damage. Anyway they wouldn't would they? Aren't there
rules for this sort of thing?
Whatever the ground people did ignoring it and simply sticking it to the air
people/pilots seems rather inadequate and a trifle scary.

-- 
Regards 
 
Mike 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Joyce Koo
Sent: Thursday, December 03, 2015 2:11 AM
To: [log in to unmask]
Subject: Re: [TN] Airbus crash pinned (in part) on solder joint failures

As I mentioned before, cd containing solder would be better for high
fatigue requirement.  I am not aware of any lead free can be a drop in fit
to replace it.  Except the wishful thinking of politically corrected type.
 Hopefully, the design was late enough, with full qual, not change
material in the mid of design phase..
> Hi Dave - yes, I would agree with you in terms of the PTH technology use
> due to a high vib/shock product environment. I was thinking more in terms
> of component evolution/introduction timeline rather than a product use
> environment.
>
> Dave
>
> On Wed, Dec 2, 2015 at 1:59 PM, Dave Schaefer <[log in to unmask]>
> wrote:
>
>> "based on the time history listed in the report, the appearance
>> of the solder joint and the technologies on the board (plated thru
>> hole), I
>> would surmise that the solder alloy is tin/lead and not lead-free.
>> However,
>> there is no technical information listed in the report to confirm that
>> assumption."
>>
>> It is conceivable that this assembly was deliberately designed using
>> thru
>> components due to the high shock / vibe operating environment.
>> Although what appears to be a lack of secondary mechanical means of
>> support on larger components raises some doubt to that thought.
>>
>> The cracked joint/lifted land appears to be bottom side ... could be the
>> result of an improperly inserted component subjected to vibration?
>>
>
>
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