Vibration at 2200-2400RPM
I have 912 ULS fitted to an Aeroprakt A32, with a two-bladed MT constant speed propeller. Total time 60 Hours since new.
The aircraft has vibration, reminiscent of an unbalanced propeller, peaking between 2200 and 2400 RPM. High RPM it's perfect and the propeller has been dynamically balanced at high RPM where the vibration is not apparent. Carbs have been overhauled and synced, still shaking. Carbs were transposed with another aircraft and the problem was still there, so I'm pretty sure that's not the issue. Trigger coil gaps checked. Modules changed. Spark plugs changed. Compression checked. Intake manifold o-rings changed. Carb sockets changed. Air filters cleaned. Throttle cables changed. I haven't pulled the gearbox as the engine is still quite new, but I'm running out of ideas.
If anyone can assist me, I'd be extremely grateful.
PS. I have 3 other nearly identical aircraft and they are smooth, so I leaning away from it being a harmonic issue with the two-bladed prop, but who knows!
