[NSRCA-discussion] Broken Hyde mount beams (my fault)

[Lance Van Nostrand]

[pattern guys, hope you find this interesting/helpful.  I had an aluminum 
beam break on my CR mount. The mount had about 1000 flights.  I sent it to 
Hyde Mounts for analysis, not knowing if he'd really be interested.  Merle 
responded right away with this. --Lance]

Merle,
I will gladly pass this on.  I'm glad you got to looking at it.  It was not 
obvious why it would break at that location.  I thought those impressions 
were due to over tightness.  I never noticed the screws being loose, but it 
makes more sense that the impressions were made by a loose engine than a 
tight one.  this has now become a much more interesting problem.  Your 
recommendation to check and retighten as part of periodic maintenance is a 
good suggestion and this experience proves it.

It is always great to work with you.  Some businessmen wouldn't want this 
information distributed, so your commitment to making the best product 
possible and your openness should be shared along with this information.

--Lance

----- Original Message ----- 
From: "hydesoftmounts" <hydesoftmounts at mymailstation.com>
To: <patterndude at comcast.net>
Sent: Sunday, April 22, 2007 6:38 PM
Subject: Beams


> Hi Lance,
>
> Its been a windy weekend here - for sure!
>
> I now know why the beam broke.  Over the years I have only had a few 
> aluminum beams break that were not crashed or impacted.  I have saved the 
> broken beams and never fully understood or conducted an analysis as to why 
> they had broken for only a few and not others.  After receiving your 
> broken beam I studied the other few I have saved.  In each case the broken 
> beam had a wear impression on it that was located exactly where the rear 
> of the engine lug caused such impression/depression by being permitted to 
> operate with the screw(s) being slightly loose.   The wear impression 
> obviously causes "work hardening" of the aluminum and the breaks have 
> always been at the used tapped hole or with some beams at the location of 
> the unused tapped hole located directly under the position where the rear 
> of the engine lug contacts the beam.  The beam breakage does not occur at 
> the position of the lightening holes which removed considerably more beam 
> material - breakage
> at the position of the lightening hole would be most obvious - but this is 
> not the case.  "Work hardening" is the only reasonable conclusion.
>
> Even nylon composite beams, that have not been crashed or impacted, and 
> that have been properly drilled/prepared, can also break at the position 
> of the "wear impression" that is created if permitted to operate with the 
> screws loose.
>
> Over the years I occasionally ran an ad in the K-Factor that advised Hyde 
> Mount users to check the tightness of fasteners/screws.  Another problem 
> some have had is that the mount may loosen on the firewall.  In all cases 
> the loosening was caused by insufficient tightening and also over time the 
> blind nuts compressed the firewall and permitted the mounts to get loose 
> on the firewall.  The key to preventing this is to tighten screws very 
> tight and also ensure "hard points" at all bolting locations.
>
> My suggestion is to ensure tightness of fasteners - and use a "T" handle 
> type allen wrench and not be timid when tightening - securing screws VERY 
> tightly, to torque specs, will not damage any part of a Hyde Mount!!!
>
> I am not on the internet, nor do I have access to the NSRCA "chat room" 
> site.  I would appreciate it if you would pass this information along - 
> others may benefit.
>
> Thanks,
>
> Merle