REFLECTOR: SAFETY ALERT - FAA warning to inspect MS21042 nuts

[steve korney]

I agree... It looks like there is a little confusion....Hmmmm


Steve 

Date: Mon, 28 Apr 2014 17:15:20 -0500
From: numa at comcast.net
To: reflector at tvbf.org
Subject: Re: REFLECTOR: SAFETY ALERT - FAA warning to inspect MS21042 nuts

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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