GT Propeller Blades

Hi all, have been made an attractive offer for a set of GT blades to retrofit to our existing Hartzell hub, some improvements in weight are obvious, C of G sorted with a lighter tail wheel but would really like to hear from anyone who has done this mod and what the real world changes are. The company claims that a lot of sets have been sent to the USA so someone out there has done this and we would love to hear from them. It is not an easy exercise here in New Zealand, the prop has to go to a shop, new weight and balance, (which I would have done anyway), the biggie being how much phase one testing our feds are going to want done. Best regards to all Jon Ludgater

I can't speak for the hartzell blade replacement, but I can say that the prop they made me is great! It really makes the radial even go!

Thanks for that, our biggest issue looks to be our feds, if they make it too hard then we will pass but your endorsement is very helpful, all the best, Jon.

I just received my set last week!!! I promised Alex at GT some comparison data between my current 7666 (74") blades and the new GT (72") blades so I will post the info and some pictures here as well. It's going to be a month or so before I get the new blades in the air as I'm finishing up some glass work on a cowl mod. I'm not 100% sure what kind of comparison tests I'm going to attempt, I was thinking maybe do a timed Vy climb to some specific attitude and then a four direction top speed run at some specific altitude with each set of blades. My MGL Voyager will record all flight and engine data (including fuel flow) so that would make the comparison easy enough,so long as there is not a huge tempature difference. Anybody with more knowledge than myself (probably most of you) have better test that I should consider? American Propeller will be installing the blades and told me it will probably be a week. They told me they would give me a credit for my old blades, but if anyone is interested in them (polished or I can have them paint and yellow tag them) pm me.

On testing: A friend found that he was getting significant variation (errors) in his data if he flew some tests in the morning and others in the afternoon. IIRC, early morning was best, because the air isn't being heated significantly. Later in the morning and through the day it's giving you free lift, and later in the afternoon it's taking all that back as the air cools & sinks. On something as subtle as a blade change, rising or sinking air might mask the actual performance change.

That and there is going to be a least a week between test flights as that is the time frame American Propeller gave me for doing the overhaul and blade swap.

Here is a pic of the blades.