Mystery Noise

Hello everyone. I have a question, I have a RV-8 with 170 hrs. I completed it about a year and a half ago. Since the beginning we would hear a noise that sounded like the cowling vibrating it seemed to be more pronounced at high attitudes and it would fade when I would yaw to the right or left. I made numerous adjustments to the cowling but the problem still existed. The weird part is sometimes it will completely go away but then return at random. Finally this summer on the way back home from Oshkosh I was in the back seat and my son was flying up front. I closed the rear vent and the sound went away and I would open it and the sound would return I thought aha mystery solved, well sort of. Now I’m wondering why am I hearing this noise through the vent? I was thinking maybe its prop tip nose because it’s closely aligned with the wing vent. Or maybe it’s the hose clamp vibrating on the vent hose in the wing. I was wondering if anyone else has experienced this?

Perhaps it is airflow past the canopy seal. You might try having a rear seat passenger push/pull or gently wedge a cloth around various areas.

Just a thought.

Don

Matt,

We had the same thing in our RV-8 - a vibration with the rear vent open. I pulled up the section of floor on the right side over the vent hose and noticed that the hose was not secured very well. The vent hose was vibrating against the belly skin when air was flowing through it. Correcting that stopped the noise.

It's a very common issue on the RV-8 for the rear canopy skirt to vibrate against the turtledeck in flight, and the sound/vibration changes pitch and intensity when yawing the rudder pedals from one side to the other. On some 8's it can get so loud you'd swear the whole tail is about to come off the aircraft.

Try adding some felt or rubber weatherstripping to the underside of the canopy skirt to cushion and seal wherever the skirt touches or comes close to touching the fuselage.

bruceg said:

Matt,

We had the same thing in our RV-8 - a vibration with the rear vent open. I pulled up the section of floor on the right side over the vent hose and noticed that the hose was not secured very well. The vent hose was vibrating against the belly skin when air was flowing through it. Correcting that stopped the noise.

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Thanks for the Idea I will check it out.