Troubleshooting Mystery Sound

[Bill Sargent]

Sorry just saw your last post. Great minds think alike.
Bill S

[gammaxy]

I think I found the problem.

I removed the 3M polyethylene tape I applied a year and a half ago to the wing gaps and the sound went away.

One piece of tape went along the top of the wing and a second along the bottom. Gaps had opened at the leading edge of the wings and the tape was peeling a little at the trailing edges of the wings, probably from moisture and dust getting under the tape. Not sure if the culprit was at the leading or trailing edges, but it seems the tape was vibrating like the reed of a woodwind instrument.

I had a very pleasant flight this evening :-)

[n502pd]

I agree with Chris! It sure sounds like a whistle, or flute, note to me.Does the note change with angle of attack, or adding lots of rudder? I also agree with the idea of temp taping any and all openings to get control of what is making the noise. One more sort of left field question: the crankcase overboard vent tube should extend below the cowl some, and a large sized hole drilled into the tube 10 or so inches above the lower cowl opening to allow breathing if the outside end becomes blocked for some reason. If the tube has rotated to be not in direct allignment with airflow, the open end and the inside hole may act as a one note flute. put some good tape on the inboard hole temporairly. For sure let us know what you find!!