engine vibration

[shafs64]

I was flying an aircraft that seemed to have a disturbing vibration at 4700 rpm but above and below that RPM it was fine.

 

does anyone have any idea what would cause this.

 

 

[mnewbery]

Harmonic vibration is exciting something. There is an article on this in the April 2015 flight safety mag. Norwegian Partnair PAR394.

 

I'd be checking the engine mounts at the engine and firewall as a start and without further information

 

 

[Downunder]

As above or could be carb balance......maybe one of the throttle cables is "catching" at that point....

 

 

[ben87r]

Ild be having a close look at the prop on the next preflight. Have had a few occasions now where a new chip would change the harmonics

 

 

[shafs64]

I am reluctant to fly the aircraft till they fix the problem.

 

 

[Kyle Communications]

The latest Sport Pilot has a article about a 701 with a rotax that has a interesting take on it. My 912ULS has the same issue...I think most of them do from the people I have asked about theirs as well. Read the article I am going to see if mine is the same

 

 

[Kyle Communications]

I have a Dynavibe prop balancer and the prop is well balanced also the carb balance is pretty good as I have a carb mate I use on my setup

 

 

[SDQDI]

I have an on ground adjustable prop and I know if it gets one blade just the smidgenest out of adjustment it will cause vibration at certain rev ranges although for me it is normally between 5100 and 5300, a quick check with the 'pitchometre' is enough to check it to confirm or rule it out.

 

Plus one for checking the engine mounts, I've seen a broken one which was only picked up because of the slight vibration in flight.