3 blade MT props for 337

there was a post on the UK site from someone with an STC to put 3 blade MT props on a 337. does anyone have contact info for the STC holder, and whether the STC includes the T337G-P?

STCNumber SA02460AT

Manufacturer: CESSNA
MakeModel:
337, 337 Series, 337A (USAF 02B), 337B, 337C, 337D, 337E, 337F, M337B (USAF 02A)

TCNumber: A6CE

Description: Replace propellers with MT-Propeller Company model MTV-12 propellers per Coastal Planes installation manual. No intermixing of propellers is allowed.

Status: Issued 4/1/02

ACO: CE-A

STCHolder:
Coastal Planes, Inc.
227 Mount Olive Airport Road
Mount Olive NORTH CAROLINA 28365 UNITED STATES

Contact Les Brindle 919-658-0064 e-mail at cpi@gte.net

Doesn't look like it includes T337G

[kevin]

Owen Bell is advertising the availability of a three blade composite prop, you might check with him.

Here is the temporary page we made with the data we received from him. We have no personal knowledge about his products...

http://www.337skymaster.com/aviationenterprises.htm

Kevin

[Bob Cook]

Hope Aero in Toronto put one together for Riley. I happened to see it or one like it at their shop last month.

Feedback and comments
Appears they are more suited to complex hi performance such as Cirrus. They can be overhauled but in most cases need to be returned to factory for blade work. Any tip damage they are history. They are laminated wood with epoxy covering. Cannot put on heated boots for front prop. They are lighter than McCauley. Very little difference in price. The amount of "meat" is greater on the McCauley. You can lose more than an inch on the diameter and still remain in spec. They are more susceptible to stone damage and FOD. Doesn't appear to have any advantage in speed but some advantage in short field performance. No documentation so far.

Hope can overhaul hubs but are limited to surface repair on the blades.

Bottom line
It does not APPEAR to provide any advantage and you could be tied up for sometime when overhaul is required (back to Germany). Since the rear prop is in the line of fire (already have redressed mine twice in one year) I would tend to stay with metal blades.

I can pass on phone numbers. Hope is a registered overhaul shop for all mfgrs including Hartzell and are the Canadian agents for MT. They assemble MT's for the Can market.

fyi

Bob

[rick bell]

what's the benefit to performance? or just that they look cook?
i e-mailed the sct holder for data; but they never replied.

[Bob Cook]

Rick

I was "told" that MT will mfgr. special complex designs which is easier to do with a wood laminated structure. Based on what I understand, a 3 bladed prop reduces vibration and noise (advantages). There is no improvement at cruise but has better loading at lower RPMs for TO or climb. MT has a weight advantange over aluminum with their design. Mooney went back to a 2 bladed prop to gain an extra 2 mph or more at cruise and was willing to sacrifice cabin noise...

bob

My understanding of the benefits are:

1) Reduced noise and vibration (permits prop. synch to actually function as intended)
2) Shorter ground roll
3) 30 or 40 lbs lighter

Downsides (from reading posts):

1) Potential cruise perf. DECREASE
2) Susceptible to FOD (particularly rear prop) - though I understand the blades can be built back up rather than being 'dressed out'
3) OH's need to go to factory (which could occur with some frequency..., see #2)
4) No front boots (though I heard you can get boots for the front)
5) Not T337G-P STC'd (yet?)

The reason I was looking looking at the MT's was because in my 337 AC search one of the birds would require new props (front and rear), and if I was replacing why not get an upgrade (if the benefits outweigh the downside).

Any first hand experience here?

[Bob Cook]

You may want to check with Mary-Anne at Riley. Apparently they have been doing tests and have experience with the Hartzell 3 blade on the Superskyrocket.

Probably the major benefits are; 1)noise, 2)weight, and 3) probably diam will be less on front prop (guess). The noise reduction would be more noticeable on conventional twins. It does change the frequency distribution of the sound waves.

bob

I am the STC holder for the three bladed mt props .
All of the upsides are true :

1) you gain approximately 60 lbs of useful load

2) the noise reduction is significant to the point of amazing

3) sync problems are a thing of the past

4)takeoff roll reduced significantly

5) front boots are available

6) mt has an overhaul facility in Deland FL and will be opening more shortly
7) Sorry about email thing try me at lesb43@hotmail.com or call me at 919 658-0064 for the rest of the story.

Les, does your STC include the T337G-P pressurized Skymaster?

G and H are not in the STC at this time FAA want,s me to test fly either model with 3 bladers on and then they will add them if anyone would be willing to let me use a g or h for a couple of hours I could have them all done.