Mailing List flyrotary@lancaironline.net Message #30307
From: Ed Anderson <eanderson@carolina.rr.com>
Subject: Apex Seal, Slot Wear was [FlyRotary] Re: Another rotary failure
Date: Fri, 17 Feb 2006 09:33:38 -0500
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Message
I think the apex seals are one part of the equation, but also the wear of the apex seal slots in the rotors is  a factor.  There is a warning in the Mazda overhaul manual about not using rotors with apex seals worn beyond specification limit.
 
  I found that Mine were over that limit when I tore it down after the apex seal failure.  I know some folks prefer to believe my apex seal failure was caused by foreign object - but, I am convinced that was not the case.
 
I believe with the apex seal slot wearing into  "V" shape slot leaves no/little support for the seal when the rotation and combustion forces causes the seal to lean back against the slot wall.  If  they wear is too much there is insufficient support for the seal and it breaks.  I did not know to check for that slot wear limit when I had put the engine together using used rotors.
 
 I now fly with new rotors and Tracy's "unbreakable" apex seals  {:>)
 
FWIW
 
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
----- Original Message -----
Sent: Monday, February 13, 2006 2:03 PM
Subject: [FlyRotary] Re: Another rotary failure

No word on the exact cause yet but did learn that Chuck was using seals from Mazdatrix.  They sell only stock Mazda seals as far as I know.
 
Tracy 
 
Is there something wrong with stock seals?  I thought they were just fine for NA engines where detonation almost isn't possible.  Your original engine ran stock seals for 800 or so hours didn't it?  Hopefully, there will be an obvious explanation when he opens it up. 
 
On the subject of failures in general, am I the only one who thinks there have just been way too many of these in the last couple years?  In virtually every case, the engine has been the victim, rather than the cause of the problem, but to the casual observer, it looks bad for the rotary.  I'd hate to calculate the number of flight hours per serious problem for currently flying rotaries.  I'd also hate for the insurance companies to do it.  Let's hope this trend doesn't continue.  
 
Cheers,
Rusty (one rotor, no prop) 
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