Brief Description: Mounting The Prop Governor - Part 1
HOBBS Meter: 1589 Hours
The Prop Governor is used to control the pitch of the constant speed prop. This means that the pilot can use a control in the cabin to set a given RPM value and the prop governor will adjust the pitch of the prop to try to maintain that set RPM. This assures that the engine is always running in the performance horsepower RPM band. For example, you would decrease the pitch of the prop when taking off to allow the engine to develop maximum horsepower when the airplane is going slower. At cruse, the engine would tend to over-speed at takeoff low pitch. The pilot can then use the prop governor to effectively increase the pitch of the prop, keeping the engine RPM in power band and not over-revving it.
The Lycoming IO-390 has the prop governor mounted up in front of the #2 cylendar. I was able to mount the McCauley governor without much issue.
Van's supplies a governor control cable bracket (white in the picture) that mounts under three of the governors control cap screws. It is interesting to note that the Woodward governors use drilled screws with safety wire here. On the McCauley governor, there is a small dab of Green Locktite instead.
The control cable (green) is connected with a ball bearing rod end and some hardware. I was able to get full HIGH RPM from the quadrant-cable-control horn combination with no problem. However, I fiddled around for the good part of two hours trying to get full LOW RPM pitch but could never get the mechanics of the setup to give it up. I'm about 1/8" away from the LOW RPM pitch stop. I asked the RV-List about this and a number of other builders reported the same exact issue. The consensus was that it was not a big deal and that full LOW RPM was rarely if ever needed.
