Bobby,
Is it possible that you were on a westerly
heading and only when you pitched down, direct sunlight was passing through the
prop onto the headset mike?
I imagine that you are thinking I’ve
really gone over the edge now.
I had a similar problem with my Lightspeed
headset that was caused by sunlight passing through the prop early in the
morning when facing east. It took a long time to figure out that placing
my hand over the mike to shield it from the light would stop the noise.
It took a longer time to get up the courage to call Lightspeed and ask them
about this. They simply said “send the headset in and we’ll
fix it.” I did that and haven’t had the problem since.
Steve Boese
-----Original Message-----
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Bobby J. Hughes
Sent: Tuesday, October 06, 2009
4:54 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Mystery Radio
Noise
Got the plane back together late
Sunday just in time for a few laps around the airport. Oil temps
showed major improvements with the larger inlets. Climbing at 100 mph to
3000 ft, 7200 rpm on take off, reduced to 6500 rpm at 500 ft agl.
Maintained 6500 rpm at 37" MP
for several circuits. Oil temps went to 220F but started to come down when I
leveled off. Water stay at 190F or below. OAT was 88F . My
new "test" ducts do not seal as well as the first set so
hopefully I still have room for improvement.
While level at 3000 ft \ ground
speed showing 145 knots I pitched the nose down and heard
a startling noise in my headset. Almost like wires shorting. Leveled off
and noise stopped. Pitched up no change. Pitch down the noise returned. I decided
it could not be wiring and repeated this several times. It also happened at
slower speeds but I don't remember at what speed it stopped. It doesn't happen
on the ground at full power run up. My guess is my new exhaust is somehow
affecting the comm antenna when in a nose down attitude. The exhaust ends about
1 ft in front and 1 ft to the side of the antenna. Any ideas?
RV-10 SC Renesis