Hi H,
I have written loads on mixture/leaning in the past.
Mixture adjustment is standard procedure on suitably equipped Enstroms and I always lean. Usually to 80-90 degrees lean of peak. Although this degree of leaning is outside the POH advisory limit, it it the best way to run a Lycoming. The injection system on my aircraft had to have a lot of work to get it to run smoothly at this mixture but it is now dead smooth to 100 degrees lean. If you go too far there is an increasing roughness and power loss way before the engine cuts dead - and yes I have done it.
On the contrary I don't feel happy running full rich. it wastes fuel, makes the engine run hot and clogs up the valve guides with crap. Cockpit carbon monoxide levels drop from 30 ppm to zero when lean. (I carry a digital detector) Fuel consumption drops from 14 to 10 usg/hour. A useful increase in range.
Running a carb Robbie lean is not possible as the mixture distribution is too poor. The injected Raven is ideal to run lean but unfortunately is not suitably equipped and you aren't going to get approval to modify it. You have no choice but to run full rich.
The risk with leaning is the brainstorm that makes you pull the knob when you want to go full rich. The silence is such a surprise and yes, I have done that as well, followed by an airborne restart.
Proper leaning and engine management of a piston heli is certainly possible but is not for the feint hearted or inexperienced.
Get it wrong and you will destroy your engine. Get it right and it turns the Lycoming into just about the most fuel efficient gasoline piston engine on the planet including modern automotive designs.
Quite a few Ppruners have flown with me and non have asked to get out when I do the lean bit.
Last edited by Gaseous; 18th Oct 2005 at 23:11.