Perry, I have had the same experience regarding wear of the Leading

plug

(Platium NG). In one case, the center electrode had erroaded completely

away

and the ceramic cone had cracked in half lenght wise and half of the

cone

was gone. Seemed to me to be more heat than the plug could handle.  I

have

come to the conclusion that because the Leading plug is a "hotter" plug

than

the trailing, its more subject to stress at the constant high rpms we

run.

I have since replace my leading plug with the "colder" Trailing plug

type

and it appears to be holding up much better.

   Every time I have a misterious slight loss of power it has turned out

to

the be plugs, but I have not been getting anywhere close to 200 hrs on

the

leading plug.

Ed Anderson

I must admit that the 200 hour figure is from the earlier days when I was
running at 30 - 35% power at cruise.  I've slowly increased my cruise power
to the 60 - 75% range and plug life is now closer to 100 hours.  I have had
the center electrode worn down to the insulator (worst case at 250 hours and
starting to get the "fading power syndrome") but never had the cracked
insulator problem.  I use only NGK plugs.

Tracy Crook
rws@altavista.net
www.rotaryaviation.com

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