The personality of the "beast" in your RV-When things change

[Pmerems]

After we complete our RV’s and have the inaugural first flight we become very familiar with all the sounds our RV’s make. Even through with the wonderful technology of ANR headsets we can still hear the “personality” of our RV’s. One of the most important sounds is the engine.

One becomes accustom and intimately familiar to the variety of sounds that emanate from the beast in the front of your RV. When the beast’s personality changes you take notice real fast. Occasionally I experience a change and I hope there is someone with a similar experience and an explanation.

I have an RV-7A with an IO-360 with a Hartzell CS prop. I have 280 hours on my bird and am intimately familiar with the engine behavior and sounds. The other day I was flying along at 5.5K at approximately 125 KIAS at 2450 rpm with a 21 kt head wind. It was a site seeing flight around some local mountains. It was a little turbulent most likely do to wind shear it was too early for thermals (6:30). I started noticing a slight change in the tone of the engine. One might call it a frequency change. It grabbed my attention, I checked the engine instruments (EFIS/EMS) all good and I reduced power a bit to see if that would change the tone. It did but I still was a bit uneasy with the initial change. I continued on with my flight and changed directions and increased power. The rest of the flight was uneventful.

I am trying to figure out why the change in tone of the engine. I am wondering if the headwind could have been varying in direction and causing the tone change. Occasionally I have experienced a tone change when performing a run up with varying wind. Could this change in the tone while airborne be caused by the 21 kt headwind changing direction?

Any thoughts or experiences would be helpful.

[scard]

I think it is quite realistic to be just a wind change. We've seen obvious extremes of the same experience.

[Infidel]

I've experienced it a few times as well. Little nuances like this keeps me alert and on my game.

[plehrke]

Complete understand the intimate "relationship" with every sound I hear in my RV. Of coarse the tone changes are directly proportional to the severity of the terrain I am flying over.

[DaAV8R]

I had a Cessna 150 many years back that seemed to have a vibration change. Some days it was smooth as silk??some days not. Some days I thought it was my imagination???..some days I thought it was real. It often resulted in me fidgeting in my seat.

Turned out to be a cracked back plate on the spinner.

As told to me by a friend, "your plane will almost always give you a warning". Sometimes the things we notice are the warnings.

Robert

[Far North Texan]

Yes they will talk to you for sure.
turbulence, gusts will all cause sound tone changes.
I never understood folks that want to listen to music while they fly. Need to pay attention to your plane.

[Chino Tom]

Originally Posted by Far North Texan

I never understood folks that want to listen to music while they fly. Need to pay attention to your plane.

I listen to music on cross country flights. It seems to me that I feel changes rather than hear them.

[Stu McCurdy]

As Tony Bengelis often said over lunch, "listen to your airplane, it is talking to you"'

I have had a change in tone and there was always a reason for it, perhaps not seen on instruments or felt in the airframe. One time I heard the change but did not see or feel the reason. Took the cowl off to find a broken exhaust just below the flange weld on #2. Another time it was a broken exhaust bracket where it exits the cowl.

[Far North Texan]

Was not meaning to disparage anyone who listens to music. I just do not.

but you sure can feel/hear an RV much more than larger heavier planes, in my experience.
Was flying with my co-pilot one day and just saw a dark flick go over the windshield and a very slight vibration started. thought maybe we had hit a small bird. We landed at the nearest airport and found that a chunk of the fiberglass spinner departed. Shortly thereafter we ordered a Sensenitch prop (which we had already been planning to do) with aluminum spinner and put the wooden prop on the mantle where it works best.

[Kyle Boatright]

Try flying the airplane with your feet on, then off of the floorboards. The sound and vibration change is enough to catch your attention until you recognize the cause.