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