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Static RPM


201Steve

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Chapter 61 in the SMM (Propellers) sez takeoff RPM is 2700 and static can be 50 below that (61-20-20).   Depending on who you talk to, 70-100 rpm less than redline is not unusual for static runup.

 

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  • 2 months later...

Here' a good explanation from McCauley:

Static Run-Up - What is Normal?

 There has been some confusion in the field concerning propeller low blade angle setting, the governor setting and how it relates to static run-up and take-off RPM. As a general rule, engine redline RPM cannot be reached during a full power static run-up. Contrary to popular belief, the governor is not controlling the propeller at this time, the propeller is against its low pitch stop. Attempting to increase propeller static run-up RPM by adjusting the governor high RPM screw will have no effect and will probably result in a propeller overspeed during the take-off roll. On a single engine aircraft several considerations determine both the low and high blade angle settings. Normally 25 to 100 RPM below rated take-off RPM is desirable and acceptable during a static run-up. McCauley's practice is to set the low blade angle so that rated take-off RPM is not reached until the aircraft has reached some significant groundspeed during roll out. At this time, and only this time, the propeller is controlled by the governor. There are two advantages to this practice. First, the maximum static RPM can be used as a check on developed horsepower as with a fixed pitch propeller. Any loss of maximum power over time is readily apparent during a preflight check. Second, if the propeller remains in a flat pitch after take-off due to some malfunction, the higher angle low pitch setting will permit more thrust to be developed to fly the aircraft without overspeeding the engine.

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9 hours ago, J0nathan225 said:

What about or where do I look for the static rpm for a 64mooney m29e with a 2 blade scimitar? Just had an IRAN on the prop and it seems alittle off I don’t make 2700 until I’m 100’ in the air.

Hartzell Manual 115N has procedures for adjusting the prop and governor.

Clarence

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6 hours ago, PT20J said:

Here' a good explanation from McCauley:

Static Run-Up - What is Normal?

 There has been some confusion in the field concerning propeller low blade angle setting, the governor setting and how it relates to static run-up and take-off RPM. As a general rule, engine redline RPM cannot be reached during a full power static run-up. Contrary to popular belief, the governor is not controlling the propeller at this time, the propeller is against its low pitch stop. Attempting to increase propeller static run-up RPM by adjusting the governor high RPM screw will have no effect and will probably result in a propeller overspeed during the take-off roll. On a single engine aircraft several considerations determine both the low and high blade angle settings. Normally 25 to 100 RPM below rated take-off RPM is desirable and acceptable during a static run-up. McCauley's practice is to set the low blade angle so that rated take-off RPM is not reached until the aircraft has reached some significant groundspeed during roll out. At this time, and only this time, the propeller is controlled by the governor. There are two advantages to this practice. First, the maximum static RPM can be used as a check on developed horsepower as with a fixed pitch propeller. Any loss of maximum power over time is readily apparent during a preflight check. Second, if the propeller remains in a flat pitch after take-off due to some malfunction, the higher angle low pitch setting will permit more thrust to be developed to fly the aircraft without overspeeding the engine.

I have always contended that I can feel my prop governor kicking in on take off....it keeps the prop from over speeding.  Typically my rpms will go up to 2690 (sometimes 2700) then drop down to 2650 and you can hear and feel the change

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9 hours ago, larrynimmo said:

I have always contended that I can feel my prop governor kicking in on take off....it keeps the prop from over speeding.  Typically my rpms will go up to 2690 (sometimes 2700) then drop down to 2650 and you can hear and feel the change

Me too.  I’ve wondered if that was just some sort of “rpm overshoot” as the engine accelerated or really the gov.  I push it up smoothly/slowly but still see what you described.  Also, my jpi930 doesn’t help because I have exact instantaneous readout of rpm vs the traditional gage where you probably wouldn’t notice it.

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