ATR72-500 prop vibrations
 

Just completed a flight where in the descent through 6000ft, smooth air conditions, doing 240kts (IAS) with the PLs set at about 36 to 40% torque experienced moderate prop vibrations through the airframe. With this sudden vibration onset the PLs were moved forward to increase the TQ to about 45 to 48%. The vibration disappeared as quickly as it came.
Passengers and Cabin Crew felt the vibration as well.

The flight profile was changed to deccelerate to < 200kts before reducing the TQ setting.

Approach and landing was normal.

This particular aircraft has a history of prop vibrations and over the last couple of months I believe the problem has got worst.

The airline and the maintenance contractor have been unable to solve the problem.

Has anyone else experienced this type of vibration and what was done to solve the problem?