REFLECTOR: SAFETY ALERT - FAA warning to inspect MS21042 nuts

[Reiff Lorenz]

Here's a photo of the MS21042-3 nuts along with an AN3-10 bolt.

I've been building the past 2.5 years and gone through hundreds of these. I've never had one crack or split. But I'll be watching for it now!

Don, I agree with you . . . I like the AN363 over the MS21042 wherever I can put them. So far the only size of MS21042 that I've really needed is the -3. But they're EVERYWHERE!

Reiff Lorenz, Dayton, OH
Velocity XL-RG, 54% complete
Currently working on: Re-planning my electrical system to use the VP-X instead of the VP-400 :-(


[cid:image001.jpg at 01CF6312.DB1FCFD0]



From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of Don Johnston
Sent: Monday, April 28, 2014 6:15 PM
To: Velocity Aircraft Owners and Builders list
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<mailto: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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