REFLECTOR: SAFETY ALERT - FAA warning to inspect MS21042 nuts

Don Johnston numa at comcast.net
Tue Apr 29 06:06:55 CDT 2014


You know the thing that's got me baffled (concerned, surprised, etc.)?

"Various manufacturers produced sporadic lots of fasteners with
non-conformities since 2008."

So it would appear that every manufacture of these has had some problems
manufacturing these nuts since they don't say "manufactured by..."

Which would seem to indicate that there is a flaw in the manufacturing
process.  They reference similar issues with NAS-1291 and NAS-625 parts. I
wonder how long before that list grows?

-Don


On Mon, Apr 28, 2014 at 5:51 PM, Reiff Lorenz <Reiff at lorenz.com> wrote:

> 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 :-(
>
>
>
>
>
>
>
>
>
>
>
> *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>
> 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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