Received-SPF: pass
 receiver=logan.com; client-ip=66.133.182.165; envelope-from=canarder@frontiernet.net
Message-ID: <42386773.503@frontiernet.net>
Date: Wed, 16 Mar 2005 11:05:55 -0600
From: Jim Sower <canarder@frontiernet.net>
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7) Gecko/20040514
MIME-Version: 1.0
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: SAG Report
References: <list-795893@logan.com>
In-Reply-To: <list-795893@logan.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit

OK.  That pretty much covers the ground for me and answers my questions 
... Jim S.

Tracy Crook wrote:

> It DOES happen in cars.  A comment by my brother who drove an American 
> Mazda 1976 Cosmo is what tipped me off to it many years ago.  It 
> happens after hours at HIGH throttle, which doesn't usually happen 
> much in cars.
>  
> Tracy
>
>
>     I have no doubt that the SAG phenomenon is exactly as described,
>     caused
>     by as described.  I am wondering when I missed the part about it
>     happening in cars or race cars or other applications.  I'm given to
>     believe that there are lots of rotarys in boats and such.  I've never
>     heard of it happening in anything except airplanes.  Are we running a
>     little bit different ignition system?  I understand that it seems to
>     have something to do with shrouded plugs, but doesn't anyone else
>     have
>     this problem with unshrouded plugs?  Would a CD ignition or
>     something of
>     the sort help?
>
>     At a loss to figure out why aviators seem to be the only victims
>     ... Jim S.
>
>     Ed Anderson wrote:
>
>     > Hi Folks
>     > 
>     > Just got back from Florida where spent weekend with Tracy and
>     Laura. 
>     > Tracy and I flew to the Leeward Ranch RV Flyin on Saturday.  On the
>     > way there I encountered the worst case of spark plug "SAG"
>     ever.  We
>     > were cruising at 4500 MSL when the old EGT started south
>     dropping from
>     > around 1650 to below 1400 F.  First on the rear rotor then on the
>     > front rotor.  Most of the time it only happens on one rotor at a
>     time
>     > and will frequently go away after a few minutes  - not this time.
>     > 
>     > I began getting a little concerned when both rotors were in SAG and
>     > seemed content to remain there.  I tried backing off the throttle,
>     > switching injector sets on and off with no avail.  This had been
>     going
>     > on for several minutes (longer than normal) when I noticed
>     something I
>     > had never noticed before - either because the SAG had never
>     remained
>     > that long on both rotors OR simply had not scan the oil and coolant
>     > temps in previous sags.
>     > 
>     > In any case, I was surprised to find the oil at 190F and the
>     coolant a
>     > 210F when with the OAT and power setting I was carrying they should
>     > have both been around 165-170F.  So it clearly looked like the same
>     > symptoms as overly retarded ignition timing.   This must have
>     lasted
>     > approx 15 minutes or more.  Finally on let down to the Flying
>     location
>     > the SAG went away and temps came down.
>     > 
>     > So on the ground I took out the sparkplugs and it was clear the
>     > ceramic white center was completely coated in lead/carbon - you
>     could
>     > see the lead crystal glint in the sun.  Both leading and
>     trailing look
>     > about the same - there was little to no detectable wear on the
>     > electrodes just the ceramic cone black.
>     > 
>     > Installed new spark plugs and flew it back to Tracy's and on home
>     > today without further incident.
>     > 
>     > Just wanted to pass this on because it can sure cause you to
>     think you
>     > may have fuel system problems when in reality its the spark plugs -
>     > especially for any of you using Avgas as I do.
>     > 
>     > Had a great weekend (as always) with the Crooks and was happy to
>     join
>     > them both at a birthday dinner for Laura's father on Saturday
>     evening.
>     > 
>     > Best Regards
>     > 
>     > Ed
>     > 
>     > Ed Anderson
>     > Rv-6A N494BW Rotary Powered
>     > Matthews, NC
>     > eanderson@carolina.rr.com <mailto:eanderson@carolina.rr.com>
>     <mailto:eanderson@carolina.rr.com>
>
>
>     >>  Homepage:  http://www.flyrotary.com/
>     >>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
>