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what kind of valve housing


herkeng3
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When you say SERVO PROPELLER GOVERNOR what do you mean like the Eletronic Prop Control?

If that is what you mean you will have sync ON/ OFF switches not Prop Governor control switches...

Different panels and warning lights for the eletronic version no warning lights just prop low oil lights...

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I am aware of the servo governor valve housing and the standard governor valve housing.

From what I can tell, the servo governor valve housing has slight different protractor readings during beta adjustments (ground idle 4-5.5 on standard; 5-6 on servo). However, because of a crew mishap report; they are not permitted to be installed on the outboard propellers. They are reported to be much more reliable than the standard governor types.

The part number of the standard governor valve housing start with a 5. The servo governor valve housings have a part number that starts with a 7. At one time, the servo governor valve housings had the filter assembly bodies painted white on the visible top.

I have yet to see a difference in actual operation.

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  • 4 weeks later...

I have had some conversations with representives of Hamilton Sundstran about the valve housings and here is a short reply I got:

"The standard governor has few parts, but it reacts slower and is less reliable.

Standard Governor Pilot Valve Operation: Either the alpha shaft or the mechanical flyweights in the speed-sensing governor physically adjusts the position of the pilot valve to direct the incoming main pump pressure to the increase or decrease pitch lines. Position of the pilot valve aligns ports in the pilot valve with ports in the valve body and serves to regulate or meter the incoming pump pressure as it is directed to the increase or decrease pitch lines. Pressure in these lines will control the dome piston position and ultimately blade angle.

Servo Governor Pilot Valve Operation: Either the alpha shaft or the mechanical flyweights in the speed-sensing governor physically adjusts the position of the pilot valve to direct the incoming main pump pressure to either the increase or decrease pitch side of the governor servo spool. As pressure increases or decreases on either side of the servo spool, the servo spool will shift to follow the movement of the pilot valve. As the servo spool moves, ports in the servo spool align with ports in the pilot valve body to direct a metered amount of hydraulic fluid from the main pump discharge to the increase or decrease pitch lines. Pressure in these lines will control the dome piston position and ultimately blade angle. The decrease pitch side of the governor servo spool is larger than the increase pitch side. Hydraulic fluid on the decrease pitch side of the servo spool serves to buffer the changes in the increase pitch pressure side of the servo spool and allows minor decreases in pressure in the increase pitch line to actually reduce overall propeller pitch through the external twisting forces acting on the propeller blades (twisting moment)."

I hope this helps.

Vic

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  • 2 years later...

DOES ANYBODY COULD TELL ME WHAT IS THE DIFFERENCE BETWEEN THE SERVO PROPELLER GOVERNOR AND THE PREVIOUS ONES, HOW CAN WE KNOW WHAT TYPES ARE INSTALLED ON OUR AIRCRAFT.

for the original 2 piece governor your P/N will be on the top of the filter bore and will be 582855

For the servo governor your P/N will be 714325-3 (civilian only) 714325-5 (military only, no beta switch) or 714325-7

The difference between the two is that the two piece governor is direct acting. It responds faster. The reliability problems have been solved IMO with a newer design bearing.

The servo governor has 3 pieces. The pieces are the governor sleeve, pitch change valve, and pilot valve.

The governor sleeve has o-rings that seal the governor to the valve housing. The pitch change valve is inside the sleeve. Both are ported appropriatly for the high pitch/ low pitch requirements. The pilot valve is inside the pitch change valve and is spun by the governor gear which has the fly wieghts mounted to it. When there is a speed change, the fly wieghts act by pushing moving the pilot valve inside the pitch change valve. This opens the ports between the two and hydraulicly moves the pitch change valve to high or low pitch depending on weather there is a over speed or underspeed. This is why it is called a servo governor and why it is slower acting.\

Hope that helps and sorry about miss spells lol

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