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Hi, Tom, I fly using 100LL 95% of the time.
For the reason you mentioned, auto gas is not
normally available on cross country trips. However, as in aircraft, spark
plugs can foul from carbon and lead. Auto spark plugs for some reason seem
more susceptible than aircraft spark plugs to lead fouling (my opinion).
We have called this the SAG (Sparkplug Attention Getter), because the engine
performance sags when this happens. EGT will drop approx 300F on the
affected rotor and rpm will drop off and it WILL get your
attention.
Before I learned to recognize its early symptoms, I once
took off on a hot day fully loaded and had SAG on both rotors - which did
adversely affect performance and condition of my seat cushion, but I was still
climbing at over 500 fpm which was more than the Cessna 150 did on its good days
{:>). So I circled the airport until I reached 5000 feet and then
by pulling back on the throttle made the SAG go away and flew on to Memphis,
Tenn.
However, I have found after 300+ hours of flying over six
years that if you change spark plugs around 20-25 hours you'll have no fouling
problems. Even when it happens, its a gradual thing - which if you
recognize the cause of the engine sub performance - can be immediately rectified
by replacing the plugs. But, if you don't it will start to happen
more frequently and for longer duration.
As you might imagine you can accumulate a lot of spark
plugs over six years changing them every 25 hours and other than the lead
fouling they clearly are serviceable for at least another 25 hours (probably
more). You can sand blast them and get the lead off the ceramic cone but
of course that erodes the electrodes. Therefore, I am looking for an
elusive solution that would dissolve the lead.
With Auto gas, Tracy Crook, is reporting over 150 perhaps
closer to 200 hours before replacement.
Hope this helps
Ed
----- Original Message -----
Sent: Tuesday, January 17, 2006 2:58
PM
Subject: [FlyRotary] Auto v 100LL
OK, so do the pilots flying use auto gas or can I
use avgas? Hay, I'm into saving $ and use auto gas, but if I'm going X/C, it's
not always available. I don't want to worry about sparkplugs fouling or
racking up gliding time (nothing against gliders mind you) Don't want to
scare my wife w/horror stories. She already thinks I'm crazy, no need to prove
her correct,,, again!
Tom RV-7
PROSEALING
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