Cowling/engine vibration

[Winterboer]

My engine cowling really vibrates with max power on takeoff and initial climb, the screws are just a blur. I just put on new Lord mounts and the prop has been dynamically balanced to .015 IPS at 2300 RPM. At 2300 RPM it is very smooth with no cowling vibration and even the compass liquid is steady.

Does anyone else have their cowling vibrate on takeoff. Any suggestions?

Mike Winterboer

 

[HammerinHank]

Cowling vibes

I am surprised you could balance the Prop if you still have a vibration. Another question would be if this is new after the balance. Look at the weights added to see if they are missing.

There is something loose if you have an excessive vibration unless it is slight and you are sensitive to this. Husky's aren't Turbines!

Otherwise check all mount bolts for torque, don't forget the mount to firewall as well as engine to the mount. Think something is loose and pray it is not internal! It is possible to somewhat hide a problem with dynamic balancing and then it gets worse. In rare cases I have seen loose cylinders even. Carburetor Air Box Valve, talked about recently as well as Muffler Baffles. A piece of Baffle hitting the cowl? Hard to diagnose from afar.

Any new sudden vibration is worrisome. Just need to do a good inspection and be persistent to find it.

 

[Snowbirdxx]

Mike,

please check if your valve rocker covers touch the cowldoors. You should be able to see some chafing marks on the rockercovers paint.
In most cases it is the rear left cylinder that has contact.
This may only be the case at full power...

You yould make a testflight with a foam in between the questioned area, but there is little hope . What I usually do is , get aircraft repair tool #1 ( delrin-hammer ) and make the rocker covers in the questioned area 1mm flatter..

TomD

 

[Winterboer]

Thomas,
The rocker cover was it!!!!

Thanks.