Hey gents,

On a new engine just installed on a new drone we are have a RPM drop when we go to 100% throttle (as indcated by the TPS) the problem is that the RPMs drop when uncommanded. We have adjusted the prop and took all of the pitch out and there was still a uncommanded drop in RPM.  I was able to pull the logs and I can see the drop in the RPMs on the graph but I cannot find what is driving the changes. If theres a good way to get the logs to someone who is willing to look at them please let me know. 

Any help suggestions would be great.


UPDATE:  After performing a various amount of checks we have determined the following. 

Fuel Filter and gascolator had contaminants in the screens. Removed plugs and found a fouled plug on cylinder 2 lane B and plenty of black soot which indicates it is running rich. Also drained our fuel cell to help clear and debris, twice. 

Cleaned gascolator, replaced filter, and replaced plugs (knowing plugs were a sympton and not the cause). Engine ran better than before however we still had the RPM drop. While experimenting with pump selection we determined that the aux pump helps create the rich condition. When on high power with one pump our EGTs were 1300 ish and when with both pumps our EGTs dropped into the 1100 which led me to believe that we had a fuel pressure regulator problem which was substantiated by a phone call to a fellow forum member. We removed the regulator and cleaned  it the best we could and did have some debris come out. We reinstalled and tried another run up and our RPM drop is not as bad but still an issue. We have a new regulator on order and will update here when we perform another high power run.  If you read this I appreciate your time to do so. If you have any opinions about this I would love to hear it. 


Thanks again. 




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