912 ULS with just over 500 hours
My direct compression tests have alway been high (180-200 psi) and as a result I never had a differential done. Yesterday I took the plane to a Rotax guy who performed a differential test and the results were not good.
Cyl
#1 76/80
#2 45/80 Suspect rings
#3 58/80 Suspect valves
#4 68/80
This morning a repeated my direct test and got
#1 200 psi
#2 160 psi
#3 188 psi
#4 190 psi
I compared the gauge to another and they matched to 120 psi. The gap between #1 & #2 exceeds the 29 psi limit but #2 is still well above the 130psi lower threshold (manual say these results should be between 130-174 ). The differential test would suggest that #2 is in pretty tough shape and it will be removed and inspected. Have others seen high direct numbers like this? is it possible to have good compression and bad leaks? The engine continues to produce 5200 rpm static which is about what it has always done.
Thoughts or comments appreciated.
My direct compression tests have alway been high (180-200 psi) and as a result I never had a differential done. Yesterday I took the plane to a Rotax guy who performed a differential test and the results were not good.
Cyl
#1 76/80
#2 45/80 Suspect rings
#3 58/80 Suspect valves
#4 68/80
This morning a repeated my direct test and got
#1 200 psi
#2 160 psi
#3 188 psi
#4 190 psi
I compared the gauge to another and they matched to 120 psi. The gap between #1 & #2 exceeds the 29 psi limit but #2 is still well above the 130psi lower threshold (manual say these results should be between 130-174 ). The differential test would suggest that #2 is in pretty tough shape and it will be removed and inspected. Have others seen high direct numbers like this? is it possible to have good compression and bad leaks? The engine continues to produce 5200 rpm static which is about what it has always done.
Thoughts or comments appreciated.
