The International Cessna^® 170 Association

About a year ago I spoke to MT about their electric props. They have one set up for the 172. For the 8 bolt hub they have nothing but did quote about 2 years and 50k to get a prop developed for the 170. They offered to sell the 172 prop but you would have to get a one time STC and manufactuer a hub adapter. The cost a little over 10k, not including the cost of getting the STC or the hub adapter.

Doesn't MT use prodominately either wood or composite construction? Wood (the ultimate composite) and composites have maintenance/inspection issues. But one reason experimental types like them is they also dampen vibrations and typically do not have the stress considerations of all-metal designs. All-metal props must undergo pretty extensive/complicated vibration testing to avoid long-term failure modes. (It's one reason the Sensenich prop has rpm-range cautions.) I wonder if that MT 172 prop isn't wood/composite?)

George,
You are right about MT being composite. I have talked to them as well. I wouldn't take them out of the running either but let's see what comes up.

Blueldr,
I don't think you have the pulse of this cult group if you think a 182 is a step up from a 170. That's like a heterosexual switching teams!

Kelly

funseventy wrote:George,
You are right about MT being composite. I have talked to them as well. I wouldn't take them out of the running either but let's see what comes up.

Blueldr,
I don't think you have the pulse of this cult group if you think a 182 is a step up from a 170. That's like a heterosexual switching teams!

Kelly

Hi Kelly,

Blueldr said the 172 drivers would step up to a 182! Hasn't ever sounded like Blueldr is anywhere close to switching teams.

Joe,
Thanks for straightening me out! It sounded like a rant at first and so that was how I read it at the end. Woops, my bad!

Blueldr,
I am very sorry about the comment I made and to make it up to you if front of everyone I would like to express how good you look in that dress! HA!

But seriously I'm sorry I read it wrong and I'll put you back on my list of good people!
Kelly

MT Props are laminated wood core that is wrapped in a protective composite. They have done exhaustive dynamic testing and found extremely limited instances of harmonic vibrations (mostly on very high compression, electronic ignition motors). They are lighter, have a much lower polar moment and have no TBO. Prop strikes w/ the MT typically shear the blades at the impact point and do not subject the engine to 'sudden stoppage'. Damaged blades are sent bact to the factory and are stripped and rebuilt to new demensions.

The 172 MT prop is avail in 2 blade or 3 blade versions. It is tested and rated up to 165HP. Larry (our U.S. MT Sales Rep) has sent a request to MT for info on a hub that would bolt on to an O-300. You are correct on pricing and time for an STC. Question to you AI's? Could you get a field approval and 337 for the use of the prop??

Kelly,

As a matter of fact, I have,on occasion, been told that I look very becomming in a dress.

Here is the url of the MT Propeller site that details the operation of their electric props. Still waiting on word of a hub that would bolt to an O-300.

http://www.mt-propeller.com/en/electrvp.htm

BloomerJohn wrote:Prop strikes w/ the MT typically shear the blades at the impact point and do not subject the engine to 'sudden stoppage'.

Both Lycoming and Continental REQUIRE engine teardown/sudden stoppage inspections if the prop requries removal for repair. It matters not if the prop is metal, wood, or putty. If you have insurance, and if you do not perform that teardown inspection...guess whose money you are saving. (Hint: It ain't yours.)

Phil,
in regard to the MT propeller for the C-172, does it fit the Continental or Lycoming model?

build it and we will buy!

Can anybody answer the question regarding a field approval and 337 for intallation of the prop that is STC'd for the 172? So if one were to buy one of these electric MT props for the 172, install it exactly the same way, could you get it signed off so you could fly with it?

MT Propeller has a hub for the Cont O-300 / C-145 engine for use with their Electric 2-blade prop. The hub fits the 541 series crank (newer). An adapter is avail for the SA-3 style flange.

This prop is 'certified'., but no STC exists. It could be put on and used on a 170 only as EXPERIMENTAL.

We would need 15 orders confirmed at $9000 ea to begin STC work.

John

BloomerJohn wrote:MT Propeller has a hub for the Cont O-300 / C-145 engine for use with their Electric 2-blade prop. The hub fits the 541 series crank (newer). An adapter is avail for the SA-3 style flange.

This prop is 'certified'., but no STC exists. It could be put on and used on a 170 only as EXPERIMENTAL.

We would need 15 orders confirmed at $9000 ea to begin STC work.

John

Hi John,

I'm curious about the costs involved in getting an STC. I assume there may be some manufacturing costs if the STC involved new or modified parts and then life cycle testing and performance testing of said new or modified parts. Aside from that what are the additional costs involved? Is there a standard fee one must pay the FAA to apply for an STC?

As an aside, I checked with xpmods (they make pponks gear legs) not too long ago about getting 140 gear legs and they were after a similar commitment, 10 orders at $5k for new steel gear legs, 10 orders at $8k for titanium gear legs.

tye

My MT source owns STC's for nearly a dozen A/C to use the MT prop. Each one took nearly 18 mos to get and between 40K-50K. FAA is real picky on tests to grant 337 on props. A tremendous amount of vibration, stress and endurance testing must be done, both on test stands and on actual A/C of the type being applied for. He would get the 337 with 15 confirmed orders. He would be at about a breakeven point at that number. Many peolple have asked him to get 337 on various aircraft, but usually this interest ends with the request for a non-refundable deposit from 15 buyers.
John