Mailing List flyrotary@lancaironline.net Message #15040
From: Kelly Troyer <keltro@att.net>
Subject: Re: engine disassembled(Hsgs split)
Date: Mon, 10 Jan 2005 17:08:52 +0000
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Leon,
    Great photos of hsgs split !! For future referance do you have photo
of front hsg split also ?
--
Kelly Troyer
Dyke Delta/13B/RD1C/EC2




-------------- Original message from "Leon" <peon@pacific.net.au>: --------------

Ooooooh, ... Aaaaaaaah,
 
My sincere condolences.  That's one of the worst "oil outs" I've seen.  From the looks of it,  the centre and rear hsgs are "thow-aways".  I'd say that if you look carefully,  you will find at least one,  maybe more cracks on the centre housing,  and at least one in the rear housing as well. 
 
I'm surprised that the front rotor is OK.  I would have expected the front side of the centre housing to have copped a bit of a hiding as well.  The front housing itself will be fine,  because the coolant passages go almost down to the gear flange,  and anyway,  the front hsg always runs cooler than the back housing as it's copping cold water from the rad.  Can we have some pix of the front side please??  As you say,  the rotor bearing looks fine.
 
You will notice how the main damage on the  back side of the centre housing is limited to where the oil cools the face.  Further out,  you have the water gallery to keep things cool.  So when the oil stops flowing,  the centre part gets hot,  and buckles like a belleville washer and grabs to rotor. 
 
I've attached a pix of a centre housing and a rear hsg split in half so everybody can see where the water gallery ends and where the oil cooled part starts. One of the other issues,  on the 6 port at least,  is the EGR passage. The pix are of an '86-'88 6 port centre and rear housings,  but the turbo housings are quite similar.
 
I'd say that the rear rotor is also beyond salvage,  especially the way the side seals have been swaged into the grooves.  Nasty!!  Being so fine,  they would be a bitch to get out,  and then the groove would be almost impossible to dress accurately.  Additionally,  the raised land inside the oil control rings looks like it has taken a terrible pizzling as well.  It is meant to be proud of the main rotor side face by about 4 - 6 thou.  Same goes for the gear side.
 
Cheers buddy,
 
Leon
 
 
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