I think what they are referring to is that MT builds northern hemisphere props.  Up north, the rain drops rotate clockwise as they fall due to the coriolis effect.  This interacts with the counter clockwise motion of the prop (when viewed from the front) that effectively causes the raindrops to get pushed away from the grease seals on the hub.  In the southern hemisphere, the raindrops rotate counterclockwise, which, unless the propeller was spinning in the opposite direction, get forced into the oil seals rather than away from them.  The only answer if you want to fly IFR in the rain down under is to get an engine and prop that spin in the opposite direction so that they interact properly with your southern rain drops.

Another query for those out there who are already flying.

I purchased a partly built L360 kit some time ago, which came with a 3 bladed, constant speed, MT, composite prop. It has never been assembled, and is by now about 20 years old. Now that I am getting closer to completing the project I have been speaking to a couple of propeller shops. As I intend to operate IFR, I asked about durability of the prop when operated in rain. The response has been a little confusing, with statements ranging from “they are not designed for ops in rain” to “ they are approved for ops in rain, but nobody actually does so” to “they are fully designed to operate in rain and will be fine”.

I would appreciate any comments from those of you out there who have operated MT composite props, as to their suitability in rain.

Thanks again for your input.

Rob Stevens

Perth,

Western Australia