scsmith
Well Known Member
When I first built my RV-8, I had an MT governor. I was able to pull to coarse pitch even at idle. So it made sense to think about pulling the prop back with the onset of engine trouble, in the hope that the prop pitch would stay coarse to improve glide ratio.
After about 7 years, there happened to be an AD on some MT governors (not mine) that led me to find that they have a six-year overhaul cycle. For just a little more than the cost of the MT overhaul, I bought a new Hartzell governor. It does not have a calendar-based overhaul interval.
One characteristic of the Hartzell governor, however is that it won't control the prop below about 1600 RPM or so. This made me wonder - if you pulled to coarse pitch while above 1600 RPM, and then dropped the RPM to idle, would the prop stay coarse? Or does the loss of prop control also allow it to move back to fine pitch at low RPM?
The answer is, it goes back to fine pitch. So, those of you, like me, with a Hartzell governor, forget about the idea of getting to coarse pitch to improve glide in an emergency.
After about 7 years, there happened to be an AD on some MT governors (not mine) that led me to find that they have a six-year overhaul cycle. For just a little more than the cost of the MT overhaul, I bought a new Hartzell governor. It does not have a calendar-based overhaul interval.
One characteristic of the Hartzell governor, however is that it won't control the prop below about 1600 RPM or so. This made me wonder - if you pulled to coarse pitch while above 1600 RPM, and then dropped the RPM to idle, would the prop stay coarse? Or does the loss of prop control also allow it to move back to fine pitch at low RPM?
The answer is, it goes back to fine pitch. So, those of you, like me, with a Hartzell governor, forget about the idea of getting to coarse pitch to improve glide in an emergency.