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  #1  
Old 01-04-2020, 10:48 AM
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climberrn climberrn is offline
 
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Question RPM fluctuations on climb out

I have an IO-360, parallel valve, 550 hours SMOH. WW 74 RV prop (250 hours SMOH) with a Jihostrov governor 400 SN. Symptoms, I get a noticeable RPM drop only on climb out. Climbing steady at 2600 RPM (max set for plane) and get an occasional drop in RPM of 50 or so. Just enough to get your attention. If I pull RPM back to 2500 or so it seems to stop. Cruise flight at 2350-2400 no issues.

Have downloaded the Dynon logs to Savvy and looked closely at MAP, oil and fuel pressures, fuel flow, EGT?s and everything else I can think of and no other fluctuations except the RPM. Been happening over the last several months.

Anything else I should check??
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  #2  
Old 01-04-2020, 11:11 AM
lr172 lr172 is offline
 
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Sounds like a governor issue. Do you cycle during runup? Maybe clearing air in the prop during climb. Possible issue with gov.
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  #3  
Old 01-04-2020, 11:36 AM
sjhurlbut sjhurlbut is offline
 
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Default Governor

Yup governor. Have had that happen before with a MT one. Called the company and see what they say. I had to upgrade mine.
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  #4  
Old 01-04-2020, 07:53 PM
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climberrn climberrn is offline
 
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Yes, cycle prop prior to takeoff. Will look into the governor. Was hoping there was another magic fix. Not so lucky.
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  #5  
Old 01-04-2020, 09:55 PM
lr172 lr172 is offline
 
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Quote:
Originally Posted by climberrn View Post
Yes, cycle prop prior to takeoff. Will look into the governor. Was hoping there was another magic fix. Not so lucky.
The fact that the RPM goes down kind of rules out oil delivery/pressure issues and just leaves the governor. I am assuming you are hearing the reduction and seeing speed drop. That rules out indication error.

Gov will probably have to go to a shop for repair.

Larry
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  #6  
Old 01-04-2020, 09:56 PM
lr172 lr172 is offline
 
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Quote:
Originally Posted by climberrn View Post
Yes, cycle prop prior to takeoff. Will look into the governor. Was hoping there was another magic fix. Not so lucky.
The fact that the RPM goes down kind of rules oil oil delivery/pressure issues and just leaves the governor, unless it is an aerobatic governor. I am assuming you are hearing the reduction. That rules out indication error.

Gov will probably have to go to a shop for repair.

Larry
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