Two plugs - Neccessary?

[gene.maurice at comcast.net]

Last time my son flew his Mooney M20J Turbo here he had to have the plugs (8)replaced (power way down @ 18,000ASL, two plugs dropping out). Cost installed $580

--
Gene Maurice 
AMA 3408 NSRCA 877 
Plano, TX 
gene.maurice at comcast.net

-------------- Original message -------------- 

> John, 
> 
> If I'm flying in a full-scale, I like having the 
> redundancy of two completely separate iginition 
> systems. :-) 
> 
> I'm not sure what you mean about two plugs making the 
> troubleshooting more difficult. Should be easy to 
> isolate. 
> 
> OTOH, changing plugs on my Dad's 182 was an expensive 
> proposition. Back in the 80's, each plug was $12, and 
> there were 12 plugs. :-( I have no idea what they 
> cost now. I guess if you can afford the fuel now, you 
> can certainly afford the plugs. The 182 holds 80 
> gallons! 
> 
> Bob R. 
> 
> --- John Ferrell wrote: 
> > Thanks for confirming my suspicions! 
> > The only dual ignition engines that I am aware of 
> > are those in highly critical applications, full 
> > scale airplanes and emergency services. My personal 
> > experience with full scale has been that the second 
> > spark plug only makes the troubleshooting more 
> > difficult. I believe the whole idea of redundant 
> > ignition is a concept whose time has past. There are 
> > twice as many things to fail. 
> > 
> > I knew a fellow who was preparing a van for his 
> > handicapped son. The law at the time required dual, 
> > isolated batteries. The mechanics acknowledged that 
> > the isolation electronics were the least reliable 
> > part of the van. That was many years back, I hope it 
> > is better now. 
> > 
> > John Ferrell 
> > http://DixieNC.US 
> > 
> 
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