Grumbling noise?

[Dave12]

Several months ago I started using Clarity Aloft Headsets. Prior to these I had been using Peltor ANR headsets. Once I started using the C/A I started hearing an odd noise from the cowling area. I only hear the noise when I cut the power and start a descent. If while I am hearing this noise that I will describe as a grumble, I add power, the noise will disappear. Also, I have noticed if I hit some turbulence, the noise will disappear, but only momentarily. The power setting that I hear this noise has to be 5k or lower, but as I say, it must be in a descent.
My guess is that the Peltor's were better at attenuating than the C/A's. I flew a few weeks ago with a Peltor and did not hear the noise which tells me the noise has been there all along. Does anyone else experience this? Gearbox? Normal (Ihope)? Thanks in advance.

 

[JBPILOT]

Hey Dave - -

I have heard the same type noise for ever I think. I have convinced myself it is the muffler with spring joints causing it. My best guess anyway. Nothing seems to fall off, so I just keep flying. With over 400 hours, I keep thinking someting will show up, but not yet.

John Bender

 

[MartySantic]

Several months ago I started using Clarity Aloft Headsets. Prior to these I had been using Peltor ANR headsets. Once I started using the C/A I started hearing an odd noise from the cowling area. I only hear the noise when I cut the power and start a descent. If while I am hearing this noise that I will describe as a grumble, I add power, the noise will disappear. Also, I have noticed if I hit some turbulence, the noise will disappear, but only momentarily. The power setting that I hear this noise has to be 5k or lower, but as I say, it must be in a descent.
My guess is that the Peltor's were better at attenuating than the C/A's. I flew a few weeks ago with a Peltor and did not hear the noise which tells me the noise has been there all along. Does anyone else experience this? Gearbox? Normal (Ihope)? Thanks in advance.

Ensure there is zero play at the flaperon ball joint rod ends. Push and pull rather hard on the flaperon at the two locations on each wing to check.

 

[sonny-m]

I have also heard a rumbling noise. I have discovered that the deck immediately infront of the windshield is oil canning.

 

[Dave12]

I found the problem today. It is the firewall "oil canning" below the oil tank. John Bender and I were talking about this situation and he told me that he had noticed an angle brace on a recent post regarding the oil tank brace. I was getting ready to fabricate a stiffener for that area and found that Van's has a kit to address this problem. The newer kits have the brace included in the kit.

 

[Dvalcik]

Are you sure?

I think it was your stomach not as many $100 hamburgers - correction $25 hamburgers IT's A RV12 (Sunoco 93 @ 4 Gal an hour)