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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
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