Metroliner: New EASA permit for quiet five blade prop
 

German regional airline Regional Air Express from Münster got their Metroliners certified for new five-blade Mühlbauer composite-props that cut cabin noise by 50 percent. Outside noise is said to be reduced too. All RAE-Metros are earmarked for conversion. RAE did the EASA certification and flight testing themselves.

German source with pic of new prop config:
RAE: Erster Metroliner mit leisem Fünfblatt-Propeller EASA-zugelassen - FLUG REVUE