Prop governor (PCU5000 ATH-1) adjustment vs. prop fine pitch stop adjustment

[DXB]

I'm working with a fresh O360-A1D overhaul. I had the 12 year old Hartzell Scimitar resealed and painted at the same time. It makes it to about 2640 static rpm, which is normal I think.  However RPM at takeoff / climb isn't any faster than that.  JPI digital tach.  The PCU5000 governor was carefully installed with the cable pushing to the full stop of the arm on the governor.

Is this a governor adjustment or a prop fine pitch stop adjustment to get to 2700?  If the former, how is it done?  I've been searching for PCU5000 manuals online but have come up blank. Can someone supply one? 

BTW, behavior was pretty similar before overall and prop reseal....engine overall was a good albeit costly experience in general - will post a full pirep later.

[EricJ]

Sounds like the governor high speed stop adjustment, but, like you say, that's not bad.   My new governor works about like that and so did the old one (neither is a PCU).

[47U]

1 hour ago, DXB said:

Is this a governor adjustment or a prop fine pitch stop adjustment to get to 2700?  If the former, how is it done?  I've been searching for PCU5000 manuals online but have come up blank. Can someone supply one?

https://cdn.prod.website-files.com/648893d6ed845c1087937b37/648893d6ed845c1087937c06_INSTALLATION-GUIDE.pdf

Here’s a screenshot…

[DXB]

38 minutes ago, 47U said:

https://cdn.prod.website-files.com/648893d6ed845c1087937b37/648893d6ed845c1087937c06_INSTALLATION-GUIDE.pdf

Here’s a screenshot…

Exactly what I needed.  The drawing is a bit inscrutable, so I'm adding a pic here for reference.  I suppose if rpm doesn't increase with this adjustment, the fine pitch stop on the prop is limiting...?

[47U]

11 minutes ago, DXB said:

I suppose if rpm doesn't increase with this adjustment, the fine pitch stop on the prop is limiting...?

Presumably… if an adjustment on the governor high rpm stop doesn’t get you to 2700.  Adjusting the limit stop is a counter-clockwise turn on the stop (screwing it out) resulting in more travel on the arm, so I think you’ll get there.  Otherwise, that’s maybe a question posed to Cody Stallings… 

[EricJ]

Usually one is hesitant to adjust the fine pitch stop on the prop, since it is usually a last resort and probably indicates something else is wrong.   It is possible to do, though, and is allowed to do.   It's usually worth exhaust all other possibilities first.  The high-pitch stop usually only affects ground operation, since it will be expected to come off the stops and start governing during the takeoff roll. 

The high-rpm stop on the governor will likely correct it, and if it doesn't, triple or quadruple check your rpm measurement standard.   You should already be using an accurate optical tach or similar.   Mechanical tachs have a fair amount of tolerance in what they indicate, and some electronic tachs and others also may have tolerances at or near the amount of error you're indicating, which is less than 2.3%.

 

[Pinecone]

Needing to adjust the low pitch stop may also indicate that your engine is not producing full rated power.  Like a static RPM check with a fixed pitch prop.

So I might get a prop shop involved to see if it is set to what it should be.

[DXB]

11 hours ago, Pinecone said:

Needing to adjust the low pitch stop may also indicate that your engine is not producing full rated power.  Like a static RPM check with a fixed pitch prop.

So I might get a prop shop involved to see if it is set to what it should be.

Kinda what I suspected as the same thing was happening when I found metal in the filter before overhaul.  Now the engine is just off the test stand making full power after overhaul, and the behavior is nearly identical, so my money is on the governor setting. I had the prop resealed at the same time by a good shop, and I doubt they set the low pitch stop too high.