Gents,
I have been experiencing a "vibration/noise" that I believe is a prop resonance issue. I was hoping someone can help diagnose this.
I have a Hartzell Blended Airfoil 72" prop purchased from Vans mounted to a Superior IO-360 with standard ignition. I have about 50 hours on the RV-7A
A few flights ago as I was on final I reduced power and started hearing a noise which sounded to me like the muffled sound of jet engine. Similar to taxing (with your headset on) parallel to the runway when a passenger jet was taking off. Lasted for a few seconds. Thought it might have been some wind noise since I messed around with a seal on my tip-up prior to the flight.
Today I was on a cross country from Tucson to Wickenburg. On the way up my RPM's were running around 2450 and ~21-22" no noise heard. On the way back I varied the setting a bit and tried 2400-2450 RPM don't recall exactly. As I reduced the MP to 21" or so I started hearing a similar sound but not as loud as the "jet engine" sound as mentioned in my earlier flight. This time I also felt a vibration.
I increased the MP and RPM and the noise/vibration went away. I have flown at these reduced setting before without any issue. However I usually fly when it is cool out but on my return trip is was hotter then normal. I have found that the engine runs the smoothest at around 2450 RPM so I don't think this noise/vibration is just engine vibration.
I haven't had my prop balanced yet. I haven't found any information about any restrictions on the prop, but I might have missed something.
Any ideas out there?
Thanks,
I have been experiencing a "vibration/noise" that I believe is a prop resonance issue. I was hoping someone can help diagnose this.
I have a Hartzell Blended Airfoil 72" prop purchased from Vans mounted to a Superior IO-360 with standard ignition. I have about 50 hours on the RV-7A
A few flights ago as I was on final I reduced power and started hearing a noise which sounded to me like the muffled sound of jet engine. Similar to taxing (with your headset on) parallel to the runway when a passenger jet was taking off. Lasted for a few seconds. Thought it might have been some wind noise since I messed around with a seal on my tip-up prior to the flight.
Today I was on a cross country from Tucson to Wickenburg. On the way up my RPM's were running around 2450 and ~21-22" no noise heard. On the way back I varied the setting a bit and tried 2400-2450 RPM don't recall exactly. As I reduced the MP to 21" or so I started hearing a similar sound but not as loud as the "jet engine" sound as mentioned in my earlier flight. This time I also felt a vibration.
I increased the MP and RPM and the noise/vibration went away. I have flown at these reduced setting before without any issue. However I usually fly when it is cool out but on my return trip is was hotter then normal. I have found that the engine runs the smoothest at around 2450 RPM so I don't think this noise/vibration is just engine vibration.
I haven't had my prop balanced yet. I haven't found any information about any restrictions on the prop, but I might have missed something.
Any ideas out there?
Thanks,