"mike regish" wrote in message
news:QRXyc.95474$Ly.16002@attbi_s01...
I was out flying the CAP's 172 yesterday when I noticed the same thing. A
growling sound. I determined that it was the soda can air vents getting
hit
by the prop wash, or rather, the openings being hit and the cans
amplifying
the sound.

What were you flying and could it have been the same thing?

Nope...the Renegade doesn't have those kinds of vents, and of course the
prop wash is entirely aft of cabin venting anyway.

I'm not ready to rule out some sort of aerodynamic effect -- for one, during
the annual inspection the fiberglass tips of the horizontal stabilizer were
replaced -- but it sure didn't seem like one to me at the time. My instinct
was that it was an engine issue.

Also, with ten years of experience flying the airplane, if it IS an
aerodynamic effect, it's almost certainly something new since the annual
inspection. Obviously I can't say that I've seen every single thing the
airplane could do, but I'll bet I've come pretty close over the years,
especially in what are otherwise normal situations such as this one.

Now that I think of it, another thing that's new is that I had them add a
second comm antenna. The sound happened in a climbing left turn, so I
suppose another possibility is some sort of vibration from the antenna.
I'll have to check into that.

I will, of course, post follow-ups to report what, if anything, I eventually
learn.

Pete