N194SP spent a couple hours in the shop getting smoother. After having the attitude indicator and the turn coordinator begin to show signs of serious wear, it was time to see if there was a common cause. The most likely culprit is just age, but contributing to that could be a propeller that is out of balance.
The plane was rigged up with a dynamic balance system and put through the paces. It was found to be about 0.3 ips (inches per second) out of balance. While this isn’t terrible and the engine mounts will absorb up to 1 ips or more before being damaged, the passengers and instruments will still feel that vibration. Generally, 0.2 ips is about where intervention should start and 0.1 ips is a minimum standard if balancing is actually performed. N194SP’s prop was balanced to better than 0.1 ips and you should feel an improvement in the quality of the ride. This was about $200 to do.