Exhaust fan noisy - squeaking and flapping noise

I need help regarding my noisy exhaust fan.
The exhaust fan is making squeaky and then flapping noise. It is particularly loud during windy day.
The exhaust fan is ducted to the outside. The model is Trader Falcon FNCEFDR.

How do I fix this?
Would replacing the external vent cover with something like this help?

I read about installing a butterfly backdraft shutter in the ductwork. But the exhaust fan is already equipped with a backdraft shutter. Will this work?

Or is there a better exhaust fan than the one I have? My friend has got a clipsal CEF40 exhaust fan (also ducted to outside) and they have no noisy exhaust fan problem.

Thanks in advance.




https://www.gsme.com.au/products/falcon-ducted/fncefd

The backdraft shutter is probably what is making the flapping noises in windy weather. Only way to fix it is to have one that doesn’t flap. Only way I have surmised to make that work is to install a manually or electrically activated one.

It's probably an expensive solution but you could look at one of these.

https://www.schweigen.com.au/catalogue/brw600

The motor unit is installed on the outside of the house which would mean with a back draft stopper there would be nothing inside the house except the tubing so wind shouldn't make a difference.

Do you have an example of this sort of exhaust fan which has an electrically activated backdraft shutter?

No, I have only seen one that you could add into the duct.