I have an RV8 with about 400 hours on it. I am not the builder, but have put approximately 25 hours on it in the last few months.
I have an IO-360 and Whirlwind RV200 prop that I had rebuilt by whirlwind when I first bought the aircraft.
On a flight last week, we had just done a touch and go and were climbing back into the downwind. Just at the top of the climb at 24"/2500, the pilot-passenger and I noticed a sound that I can only describe as having a turboprop flying somewhere close in our vicinity. I felt it was coming from up front by the prop, the passenger who is also a pilot felt is was coming from below us. The sound remained with MP and RPM changes, and did not change much in pitch or volume. By the time we returned to our home airport 15 miles away, it was gone. It was not loud, or scary, and I couldn't perceive any associated vibration. Only the sound.
On the ground we theorized that it could be a panel vibrating that I recently attached a cupholder to.
Yesterday, we went up again to test, and through all different power and climb/cruise configurations, we could not get it to come back. When returning to the airport, we initiated a decent of about 1500 fpm at around 15"/2400 rpm and the sound came back. I added MP and began to climb so we could spend some time diagnosing, and it immediately went away. We could not get it to come back.
My passenger was quick enough to push on the panel the cupholder was on, and verified that it was not the problem.
I never heard this in the previous 22 hours I put on the aircraft.
I have checked the following between the first flight and yesterday:
-I checked the entire exhaust system
-Looked at everything with the cowling off
-Spinner is tight, true, no rubbing
-Prop blades are tight, clean, and tapping the entire length, both blades sound the same
-Wheel pants are tight
-We did not notice any flutter or vibration through any controls
-Wing root rubber strip is secure
-All panels and fairings are tight and secure
Any thoughts on how I can diagnose this? It might be nothing, it might be something. Intermittent problems are the worst!
I have an IO-360 and Whirlwind RV200 prop that I had rebuilt by whirlwind when I first bought the aircraft.
On a flight last week, we had just done a touch and go and were climbing back into the downwind. Just at the top of the climb at 24"/2500, the pilot-passenger and I noticed a sound that I can only describe as having a turboprop flying somewhere close in our vicinity. I felt it was coming from up front by the prop, the passenger who is also a pilot felt is was coming from below us. The sound remained with MP and RPM changes, and did not change much in pitch or volume. By the time we returned to our home airport 15 miles away, it was gone. It was not loud, or scary, and I couldn't perceive any associated vibration. Only the sound.
On the ground we theorized that it could be a panel vibrating that I recently attached a cupholder to.
Yesterday, we went up again to test, and through all different power and climb/cruise configurations, we could not get it to come back. When returning to the airport, we initiated a decent of about 1500 fpm at around 15"/2400 rpm and the sound came back. I added MP and began to climb so we could spend some time diagnosing, and it immediately went away. We could not get it to come back.
My passenger was quick enough to push on the panel the cupholder was on, and verified that it was not the problem.
I never heard this in the previous 22 hours I put on the aircraft.
I have checked the following between the first flight and yesterday:
-I checked the entire exhaust system
-Looked at everything with the cowling off
-Spinner is tight, true, no rubbing
-Prop blades are tight, clean, and tapping the entire length, both blades sound the same
-Wheel pants are tight
-We did not notice any flutter or vibration through any controls
-Wing root rubber strip is secure
-All panels and fairings are tight and secure
Any thoughts on how I can diagnose this? It might be nothing, it might be something. Intermittent problems are the worst!