We are currently running a maule M4 "experimental" on amphibian floats and powered by a Comanche engine and prop - lycoming O-540 A1D5 (250hp). The prop is subject to a recurring AD and I want to change it as at 79" it's not much of a sea plane prop anyway.

The problem is this engine was not on much else other than the comanche so both hartzell and Mac have no long blade test results and won't suggest anything to be vibration approved. Even though I am in the experimental cat I would like to stick pretty close to approved props other than the possibility of composite props.

Even though there is no MT stc for this engine their claim is that their composite props virtually eliminate harmonic vibrations....... What's the feelings out their? can you hang a composite prop and never worry about harmonic vibrations ????

I also see MT has an stc for the Comanche 400 but not the more popular 250?? What's up with that?could their be issues there ?

I am mostly interested in MT as our prop shop is a dealer.

I am running a Ivo composite prop on my High Horsepower experimental... The elasticity of a composite prop does a wonderful job of absorbing vibrations/ harmonics, IMHO much better then aluminum or wood props do. All you have to do is make it crystal clear to MT you are in the "experimental" catagory and MT will give you darn good product support and application feedback........ Just bring your checkbook....... I am betting they will want $ 13,000 + for a prop that fits your needs......


Ben.
www.haaspowerair.com

Contact Larry S. at Flight Resource: http://www.flight-resource.com/?gclid=C ... Kgod-VV_Gg

If anyone can answer your questions it's Larry or John at Flight REsource.

As far as vibration goes, virtually all propellers mounted to a Lycoming O-360 A1A require either a harmonic damper assembly (ten pounds of excess weight) OR rpm restrictions to avoid harmonic issues. The MTV 15 requires neither. These propellers, being of composite design (wood core, composite sheath, metal leading edge) do a great job of dampening vibration. So do wood propellers, by the way, but I don't know of any wood propellers for these higher hp engines.

Give Larry a call. He'll shoot you a straight story.

MTV