912 gearbox

[wypaul 460]

The 912 ULS gearbox should be sent in for rebuild before 1000 hrs.  The dogs wear out and must be replaced.  Failure to do so results in the gears failing also.  You will know that you have waited to long when you throttle back on final approach and you experience vibration.  Hopefully the newest engine with the oil spray tube will take care of this issue of dog wear.

[Av8r3400 1188]

I have rebuilt several gearboxes and find that most should be torn down and at least inspected and re-shimmed every 300 hours.  

Most guys don't run their 912 engines at high enough RPM and this it a killer for the gearboxes.

[saskavid 48]

So in your opinion what rpm is is too low to run these engines? 

[Av8r3400 1188]

So in your opinion what rpm is is too low to run these engines? 

By the book, 5000 RPM should be the minimum continuous operating RPM.  

I have run across several experienced "legacy engine" pilots that think lower rpm is better on these engines.  This couldn't be farther from the truth.  Hal told me to run the hell out of my engine.  (His design Zipper big bore)  He said don't be afraid of 6000 continuous.  I don't run that hard, but I do maintain a minimum of 5000 for local puddle jumping and 5500 for x-country.