Hi H,
Enstroms are equipped with graphic engine monitors with EGT sensors which make it feasable to run lean. You are quite right that without this, and vernier mixture adjustment, and experience, and training leaning should not be attempted.
In terms of engine life, Enstroms seldom make TBO as most pilots do not run them at optimum mixtures. (in my opinion). Often they do not make more than 400 hours without a top end overhaul!!
A correctly managed engine will last longer than one thats run full rich all the time. As likely as not it will do 1500 lean hours no problem.
Full rich, valve gear is usually first to fail due to stem fouling. Bearing loads are higher when full rich and oil contamination is worse. Temperatures are hotter. All these things shorten engine life.
All that said, without the right equipment, training and experience, DO NOT mess with the mixture.
I wouldn't lean a Robbie either.
Your Robin lean find technique is probably not ideal. You need to be on the other side of peak. Check out John Deakins 'Pelicans perch' writings on AVweb. Maybe your Robin's mixture distribution is too poor to run lean. That can happen, even with injection.
Its not just about saving a tenner. It also allows my helicopter a 30% increase in range or an increase in payload by not needing extra fuel, which is worth more than money, as well as all the other benefits.
Sudden engine engine failure is not an issue with a vernier mixture adjustment as if you do go too far, the heli will warn you in good time by increasing roughness and gradual power loss with yaw. You just bang the mixture back to rich and do it again.
Cheers
Phil
Last edited by Gaseous; 23rd Oct 2005 at 01:33.