Vibration after pitch change
in 912 / 914 Technical Questions
7 years ago
I have reciently purchased a 500 hr sportcruiser with Sensenich 3 blade ground adjustable prop. The static WOT would reach 4900 rpm max. As Rotax suggest 5200 rpm I reduced the pitch and now get a takeoff rpm of 5100 - 5200 but there now is a noticable vibration between 3000 - 4500 RPM reducing the higher the revs until it is bearly noticable above 5000 (On decent the vibration is much less noticable). Prior to the pitch change the engine was smooth across all revs. I have rechecked all blades for pitch and track and all is good. I also noted prior to the pitch change the oil ran cold 70deg C and pressure was around 40psi.(OAT mid 30C) Now oil temp is right in the green 90 - 100 deg C and pressure at 45 - 50 psi. WOT in flight gets 5600. I put this down to the engine not working as hard and running leaner, plugs indicate that as well. Could this vibration be in the gear box as the load is less now the pitch is finer. Is it indicating a pending dog problem.
Also the Rotax mechanic at our field strongly suggests replacing the floats at 500hrs but i cannot see any reference from rotax suggesting this, only testing their weight. is it a normal practice to replace floats every 500 hrs?
Also the Rotax mechanic at our field strongly suggests replacing the floats at 500hrs but i cannot see any reference from rotax suggesting this, only testing their weight. is it a normal practice to replace floats every 500 hrs?
