MT Propeller
There are two commonly used certified manufacturers of constant speed propellers.
The MT Propeller you are asking about should be a MTV-12-B/183-59, or a MTV-12-B/183-59b designation. Both for a Lycoming (I)O-360/390 engine.
The earlier -59 blade design propeller has RPM restrictions around 2200 RPM. The -59b blade design propeller does not have this RPM restriction.
I would guess that the previous owners mission profile was primarily cruising at, or above, 7,500'. This is where the performance advantage goes to the three bladed propeller.
Additionally, when a 2 blade propeller and a 3 blade propeller are dynamically balanced to the same level, in flight the 3 blade MT Propeller is significantly smoother than a metal 2 blade propeller.
This is important from a fatigue standpoint for longer distance cruise and passenger comfort.
Having a smoother operation would not very important for the full throttle full RPM why bother to waste time to climb out of the turbulence macho type pilot. (Gee, I hope I didn’t over characterise this. J )
MT Propeller maintenance can be erratic, depending on customer location. In the USA it is usually pretty good. (Just DON’T tell the maintenance shop they can take their time. Propeller repair and overhaul always need to be done right away!)
Regards,
Jim Ayers