REFLECTOR: SAFETY ALERT - FAA warning to inspect MS21042 nuts

[Don Johnston]

That page shows what appears to be a "Spring Beam" lock nut. I've ordered
these using the AN363 part number. They are used in high temperature
environments.

http://www.aircraftspruce.com/catalog/hapages/an363.php

My understanding is that MS21042 are "Distorted" lock nuts.

http://www.aircraftspruce.com/catalog/hapages/MS21042.php

-Don


On Mon, Apr 28, 2014 at 4:13 PM, steve korney <s_korney at hotmail.com> wrote:

>
> Sorry.....
>
>
> Here is a link to what the MS21042 nut look like...
>
>
> http://www.fastenal.com/catalog_pages/2009/3-349.pdf
>
>
> Steve
>
> ------------------------------
>
> Subject: REFLECTOR: SAFETY ALERT - FAA warning to inspect MS21042 nuts
>
>
>
> The FAA has released a Special Airworthiness Information Bulletin warning
> the aviation community that there have been reports of bad batches of
> MS21042 nuts manufactured since 2008. The report claims that some of these
> nuts in sizes -3 through -6 have experienced cracking due to hydrogen
> embrittlement and other manufacturing defects.
>
>
>
> Velocities use these nuts everywhere, especially MS21042-3, which can be
> found in critical components like the elevator hinges and most torque tube
> connections.
>
>
>
> The recommendation is for all aircraft owners to inspect any of these
> fasteners that are in "safety significant applications" at the next
> opportunity. Look for cracks in the wrenching surfaces; use a 10x
> magnifying glass, if possible.
>
>
>
> There is a further recommendation that unused batches of these
> self-locking nuts should be torque tested by sampling the lesser of 10% or
> 20 pieces from each batch in inventory.
>
>
>
> The full report and further details of the recommendation (including how
> to report if you find defective parts) may be found here:
>
>
>
>
> http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgSAIB.nsf/0/3D89878925EC2F1C86257CC800611B60?OpenDocument&Highlight=hq-14-16
>
>
>
> (If the link above doesn't work, search for HQ-14-16 at:
>
>
> http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgSAIB.nsf/MainFrame?OpenFrameSet)
>
>
>
> Please report to the group if you have any additional information on this
> warning.
>
>
>
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