REFLECTOR: Enhanced photos Cozy Loss of Catto Prop

[Jim Agnew]

I just received the following note from Craig Cato and I'm posting it since it contains some important information.
 
I took five of the Cozy pictures and enhanced them increasing their sharpness and contrast, the failure mode is clearly visible.  The center flange looks like it is threaded as do the drive studs and one stud (the one opposite the last bolt) looks like the prop was moving almost 1/4".  Sam DaSilva looked at the original pictures and we were speculating the the prop finally departed the one remaining bolt and was slung away by the remaining bolt which caused the bending of the bolt attachment stud.
 
I can't attach the 5 pictures due to their 1.5MB each size so if anyone has a way to post them let me know.  
 
Jim
 

----- Forwarded Message ----
From: Craig Catto <cattoprops at cdepot.net>
To: Jim Agnew <Jim_Agnew_2 at yahoo.com>
Sent: Wednesday, December 20, 2006 11:57:00 AM
Subject: RE: Enhanced photos


Jim,
OH my gosh!!!.. thanks for the pics!,,   
One thing sticks way out to me, and have seen spinner failures due to this and other props that have worked due to this. From what I see, it looks like there is fabric imprinting on the face of the extension.  IF a composite spinner bulkhead was used, I have high suspicions this was a culprit.  I do not recommend a composite bulkhead ever be used in-between the power transfer surfaces, extension to propeller.  I have also seen painted aluminum bulkheads on many installations that have shown signs of working and do not recommend that the aluminum area of power transfer be painted in any fashion.
 
The problem is the resin in a spinner bulkhead and or paint on a aluminum bulkhead usually will not handle the heat associated with this power transfer if there ever becomes any small movement.  Like rubbing your hands together, friction, amplify this by thousands in frequency and the heat generated in a very short period of time will break down the resin and or paint  in the area of power transfer.  Once this happens, you now have a lubricant in-between the extension and propeller, and the inevitable will happen. With the composite bulkheads, once heat reaches a point it will flow ever so slightly causing a dramatic reduction in bolt torque!
 
I have not talked with Zeitlin or seen the article of this incident yet, only pictures sent to me from Jim Agnew. These pictures of the fabric imprint of the possible use of a composite bulkhead raised loud alarms to me.  If anyone is using this type of spinner bulkhead, I do not recommend it be used.  I personally have seen to many of them that have shown signs of working and causing torque values to reduce. And recommend on a aluminum bulkhead that the paint be removed in the 7" diameter area of power transfer.
On the composite bulkheads, you can either replace it with an aluminum one, or cut out the inner area and rivet on an aluminum circular plate. 
 
Jim, if you could please post this immediately I would sure appreciate it.
Regards,
Craig Catto
 
 
 
 
 
-----Original Message-----
From: Jim Agnew [mailto:jim_agnew_2 at yahoo.com] 
Sent: Wednesday, December 20, 2006 8:09 AM
To: Craig Catto
Subject: Enhanced photos


Hi Craig, I enhanced 5 key photos so you can see them better.
 
Jim
 
James F. Agnew
Jim_Agnew_2 at Yahoo.Com
Tampa, FL
Velocity 173 Elite Aircraft Completed & Flying
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