A bit of technical info - a lot of operators were or may not be aware of regarding original PA31's - to my knowledge, it was illegal to operate Navajo's with wing lockers unless they had 3 bladed props and a change of elevator mass balance weights.i believe this was an asymetric issue because unless this configuration was fitted it created a serious control problem from the early models which did have 2 blades until the later ones which came out with standard 3 blades, if an engine out situation occurred.
Glen Beard