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Date: Tue, 15 Apr 2008 11:44:08 -0500
From: David Staten <Dastaten@earthlink.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Uh oh, this can't be good - RD-1B PSRU woes
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Tracy Crook wrote:
> Not good indeed.
>  
> Two or possibly three causes for this.  but before detailing these, 
> take note of the "larger sized rollers" in the pix.  Those look like 
> the input shaft has sheared off the drive pin.  Probably caused when a 
> roller got in the gears and locked up momentarily.  I'm kind of 
> surprised no one noticed any of this mayhem going on during testing.  
> The dripping oil at the input shaft was no doubt due to the seal being 
> distroyed by heat.  The race melted for the same reason.
>  
> 1.  No oil to the thrust bearing.  .,....  Oil for the drive must come 
> from the oil system _after_ the filter.
We used oil after the filter (external filter btw cooler and block), 
then took oil from the oil pressure sending port on the block, through 
an AN4 stainless hardline. Was planning on replacing with an AN4 
softline. Will have to check the hardware for port obstruction or 
interference.
>  
> 2.  This same type failure happened on another drive when a late model 
> input shaft was used with an early adapter plate that did not have the 
> deep bevel for clearance of the shaft radius.  Check adapter plate for 
> signs of interfearance.
>
> 3.  Not likely, but check to be sure the snubber(s) is in place to 
> insure proper end play of input shaft.  if it is excessive, rear race 
> of thrust bearing can drop down and cause all manner of problems.  B 
> drives may have 1 to 3 molly impregnated nylon snubber washers.  All 
> that were shipped with drive should be installed. 
I dont recall any leftover parts from our initial mateup and 
installation but its been quite a while.
>  
> I assume the drive is on it's way back so I'll let you know what I find.
>  
> Tracy
Dave