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7A Whistle

N164BJ

I'm New Here
Recently I have been instructing in a 7A. I have built and fly a -6. Three flights ago, the 7A developed a deafening whistle. So loud it is hard to communicate through ANR headsets. We have removed the main gear fairings and wheel pants as well as an external camera mount in an effort to isolate the cause, no luck. It is influenced by air speed, increasing or decreasing in volume as speed increases or decreases. Non existent below 110 mph. Any ideas besides flying around at 109 mph? Thanks for the input!
Joe
 
Recently I have been instructing in a 7A. I have built and fly a -6. Three flights ago, the 7A developed a deafening whistle. So loud it is hard to communicate through ANR headsets. We have removed the main gear fairings and wheel pants as well as an external camera mount in an effort to isolate the cause, no luck. It is influenced by air speed, increasing or decreasing in volume as speed increases or decreases. Non existent below 110 mph. Any ideas besides flying around at 109 mph? Thanks for the input!
Joe

An almost closed air vent?
 
Is it a tip-up canopy?
If so, does it have a molded fiberglass targa strip on the aft edge of the canopy?
If not, this is a common location for an air leak that can turn into a very annoying howl.
 
I had a piece of chafe tape that became delaminated which was under my canopy skirt up against the fuselage. When it came loose it really whistled! Marty
 
A slider w/s fairing will also produce a loud howling noise if it begins to separate away from the plexi. Starts as a shrill whistle and progresses to something sounding like the whole canopy beating its self to pieces.
 
Did you fly near Scio OR yesterday? I heard a whistling plane and looked up as a RV was hauling *** by and had a defendant whistle...
 
Canopy seal

I had a similar experience on a -7 Tipup that I test flew. The owner hadn’t fitted a canopy seal. No noise until about 100 kts then it was almost deafening by 120.
After the seal was fitted silence!
 
Thank you all for your feedback. This is a slider canopy and we were flying north of Eugene but not quite to Scio. Would not surprise me if it was audible on the ground. Did quite a bit of air work with out the whistle and then increased airspeed to 150 mph and the whistle started. Thanks again! I will post the eventual solution. Best regards, Joe
 
This is a slider canopy

That being the case, does it happen to have any plastic or UHMW tape applied to the inside of the canopy skirts for scuff protection?
If so, and if any of it is loose, it can act like an instrument reed and make a huge amount of noise.
 
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