here's a question,
I currently run a 74 DM 58 Sensenich metal prop on my pacer. I have been considering trying to get a 337 approval to put a fixed pitch MT prop on. The reason is I'm going to need a new prop soon (mine has been overhauled, etc.) and I would like to have a composite for the lighter weight, less vibration. But, with the same length, pitch how would the two perform against each other?

Is there a performance loss/gain with a composite things being equal. My intuition is that you can gain a bit of RPM due to the lighter weight composite without burning extra fuel. But I don't know.

First thing to do is to find out if there are ANY approvals of the propeller you're interested in on the engine you have in your airplane. If not, you won't get a field approval without a complete vibration survey. If there is an approval (STC) of that propeller on the same engine as in your airplane, you MAY be able to get a field approval, but I'd go through the field approval process FIRST before I plunked down money. If your mechanic submits it and the FAA approves it, you're good to go.

And, the only way you're going to find out if there's a performance change is to find someone who has a similar combination. Good luck.

MTV

If you check the type certificate for the pacer, you will likely see that in the approved propellor section, any fixed pitch prop meeting the dimension limits stated, and turning in the rpm limits stated are approved.
I have run two airplanes with the fixed pitch MT, and had mixed results. One was a 90 hp Champ, and it was fantastic. Smooth, great performance off the ground, and fast in cruise. I could really feel the weight difference as well.
The second plane was a 160hp Murphy Rebel. I asked MT to supply a prop that would perform as good as the Borer I was using, and they said they would, or my money back. The prop turned the exact static RPM that they said it would, but it had MUCH less thrust than the Borer.
The prop was smooth, and light, but just didn't pull. I believe the longest fixed pitch they can make is 74", and there is no way to make that work as well as an 82" Mac.
I sent it back and got a full refund, no questions asked.

side slip wrote: If you check the type certificate for the pacer, you will likely see that in the approved propellor section, any fixed pitch prop meeting the dimension limits stated, and turning in the rpm limits stated are approved......

I have never seen "or any fixed pitch prop" approval in a TCDS except for when they're talking about wood props. And lo & behold, Pacer TCDS # 1A4 says for the O-235-C1, O-290-D, & )-290-D2:
"....or any other fixed pitch wood propeller which is rated for the engine power & speed."
Now the two questions are
1) Is the MT prop considered fixed pitch? It's my understanding that their "fixed pitch" prop is actually a ground adjustable. Does that qualify per the TCDS?
2) Is the MT prop considered a "wood prop"? Again, my understanding is that it is composite: fiberglas or carbon fiber or something over a wood core. OK or not?
If the price of admission (purchase and/or approval) for an MT is too high, keep in mind that people have been running Sensenich 74DM's on these small Lycomings for years & getting great results with them. If STOL op's are part of the mission, a Macauley GM8241 "borer" might be a better choice.

I recently saw a fixed pitch(not ground adjustable)MT on an 85hp J-3.I don't know if it was an approved install or not but the owner said it worked very well.

Bill

The MT is a wood prop. They are not adjustable. They are fiberglass coated, and are available with a stainless leading edge for float ops. When you hold one, it looks no different than a standard wood prop, other than the colour. Standard woodprop rules apply, crush plate, bolt retorque, etc.
I'm pretty sure they are made of ash, the one I had installed on the champ looked to be ash, after it disintegrated impacting the ground.

Googled up MT's website & their fixed-pitch prop does indeed look just like a standard wood prop except for the color. I do notice that they refer to it as "natural-composite" not wood. Splitting hairs I know, but an awful lot of aviation approvals seem to involve some of that. I guess it's up to your IA and/or your local FAA inspector whether the MT qualifies as wood or not.
The downside of a prop like this , whether plain wood or coated with something, is fixed pitch REALLY means fixed pitch-- no re-pitching like with an aluminum prop. So if you go this route, think long & hard about length & pitch before yu place your order.
Another aspect to this sort of prop is the weight-- a simple wood or composite prop is likely gonna be quite a bit lighter than a Sens or Mac metal prop. Crunch all the numbers first to be sure that your final W&B will be within legal limits per the TCDS. Sometimes when you take too much weight off the front end, it adversely affects how much baggage you can carry at the other end. Tailheavy airplanes generally stall slower & fly faster but can be squirrellier on the ground- esp taildraggers.

If I remember correctly, I think the MT I put on the 90hp Champ weighed 9 lbs. The Mac was around 30.
It was a massive difference in flying qualities.

The pacer/tripace was designed around the smaller o-290 engine and some had wood props. Later, when they added the o-320 with the slightly larger metal prop, especilly the tripacer, they added a lot of weight to the front end. There would be no problem at all dropping 10 or 20lbs off the nose of my plane and it woudl likely improve the flight charateristics which is also why i want to look into the MT.

They are ash wood laminant core. As for length and ptich i was thinking that I would use the same as I have, 74 with a 58 pitch. But, I was wondering if the lighter weight of the prop would affect performance. for example, would i get an extra 50 rpms just because the engine if turning a 20# lighter prop?

You will probably find that you need to go a bit finer pitch than you would on a metal prop.
Because the MT is wood, the blade root is much thicker than an equivilent metal prop, so there is significant drag in that area.
I think the MT is measured in metric, so you will need to do the conversion back to inches.
They can spec out the optimum prop for you, just make sure to tell them it is going back if it doesn't perform as advertised.

Actually, as I noted earlier, before you go any further with this, you should find out if there is an approval for this propeller, either an STC for installation on your airplane, or at the very least, an approved installation on an engine of the make/model you have on your plane. IF the latter, you will need to field approve the prop, and I'd get that done BEFORE I laid down any money for the prop. The approval will probably dictate the prop diameter and pitch limits, as well. It doesn't make much difference what you want, in a certificated airplane, it's what is APPROVED or approvable that will dictate the prop pitch and diameter, as well as the prop itself.

Call Flight Resource and talk to Larry or John. They can give you a lot of help on this.

MTV

I looked into putting a MT on my Luscombe. The TC has those magical words "any wood prop that meets XXX limits." Emailed flight resourced and they said the fixed pitch MT are certified as wood props and would be legal to install. I am waiting to decide if I am going to keep the Luscombe or not.

mtv wrote:Actually, as I noted earlier, before you go any further with this, you should find out if there is an approval for this propeller, either an STC for installation on your airplane, or at the very least, an approved installation on an engine of the make/model you have on your plane. IF the latter, you will need to field approve the prop, and I'd get that done BEFORE I laid down any money for the prop. The approval will probably dictate the prop diameter and pitch limits, as well. It doesn't make much difference what you want, in a certificated airplane, it's what is APPROVED or approvable that will dictate the prop pitch and diameter, as well as the prop itself.

Call Flight Resource and talk to Larry or John. They can give you a lot of help on this.

MTV

The USA must be different in this regard than Canada. Here in Canada there is no approval required. The MT is a wood prop, and the Type Certificate states that ANY wood prop meeting the listed specs are approved. For us north of the border, it is a simple signout that the prop was installed, and go fly. The longest part of the job is the lockwiring.
I'm really not sure why the FAA would require a field approval on an item listed on the Type Certificate.

side slip wrote:

mtv wrote:Actually, as I noted earlier, before you go any further with this, you should find out if there is an approval for this propeller, either an STC for installation on your airplane, or at the very least, an approved installation on an engine of the make/model you have on your plane. IF the latter, you will need to field approve the prop, and I'd get that done BEFORE I laid down any money for the prop. The approval will probably dictate the prop diameter and pitch limits, as well. It doesn't make much difference what you want, in a certificated airplane, it's what is APPROVED or approvable that will dictate the prop pitch and diameter, as well as the prop itself.

Call Flight Resource and talk to Larry or John. They can give you a lot of help on this.

MTV

The USA must be different in this regard than Canada. Here in Canada there is no approval required. The MT is a wood prop, and the Type Certificate states that ANY wood prop meeting the listed specs are approved. For us north of the border, it is a simple signout that the prop was installed, and go fly. The longest part of the job is the lockwiring.
I'm really not sure why the FAA would require a field approval on an item listed on the Type Certificate.

There are approvals and there are approvals.....and there are approvals in Canada as well. Whee actually answered the additional question, the first question being if "any wood prop" is approved on the TC. The second question is whether the MT prop is defined in the regs as a "Wood Prop", by definition. Whee noted that this is the case.

So, yes, it's good to go. But, my point was that you need to find out that basic information first, in the US, and in Canada. You can't just bolt any prop on any engine/airframe in either country....there has to be a basis of approval.

MTV

Sorry for bringing up a flash from the past, but on a similar note, would a ground adjustable prop be considered "fixed pitch" in that in can not be adjusted in flight? Also, on a much less similar note, has anybody ever heard of an aircraft getting a field approval to mount the sensenich carbon fiber ground adjustable prop on a certified aircraft? (specifically on a continental 0-200) Experimentals have been using them for a while, and when you combine the light weight and ability to adjust the prop for the conditions and mission, it seems like a no-brainer. Or if im just crazy and should forget it, feel free to let me know

Here is the link to the prop in question: http://www.aircraftspruce.com/catalog/a ... ctor-5.php

jlacharite wrote:Sorry for bringing up a flash from the past, but on a similar note, would a ground adjustable prop be considered "fixed pitch" in that in can not be adjusted in flight? Also, on a much less similar note, has anybody ever heard of an aircraft getting a field approval to mount the sensenich carbon fiber ground adjustable prop on a certified aircraft? (specifically on a continental 0-200) Experimentals have been using them for a while, and when you combine the light weight and ability to adjust the prop for the conditions and mission, it seems like a no-brainer. Or if im just crazy and should forget it, feel free to let me know

Here is the link to the prop in question: http://www.aircraftspruce.com/catalog/a ... ctor-5.php

https://www.faa.gov/regulations_policie ... ak_ch7.pdf

Looks like the FAA makes a distinction between Fixed Pitch, Adjustable Pitch and Constant Speed.
I'd say that ruled out ground adjustable props like the one in the link.

Also, the description of that propeller is different from a wood composite. "..manufactured using an internal pressure, closed mold system to produce a hollow, one piece blade.." It would at least need a wood core to be considered a wood prop.

Bagarre wrote:

jlacharite wrote:Sorry for bringing up a flash from the past, but on a similar note, would a ground adjustable prop be considered "fixed pitch" in that in can not be adjusted in flight? Also, on a much less similar note, has anybody ever heard of an aircraft getting a field approval to mount the sensenich carbon fiber ground adjustable prop on a certified aircraft? (specifically on a continental 0-200) Experimentals have been using them for a while, and when you combine the light weight and ability to adjust the prop for the conditions and mission, it seems like a no-brainer. Or if im just crazy and should forget it, feel free to let me know [emoji38]

Here is the link to the prop in question: http://www.aircraftspruce.com/catalog/a ... ctor-5.php

https://www.faa.gov/regulations_policie ... ak_ch7.pdf

Looks like the FAA makes a distinction between Fixed Pitch, Adjustable Pitch and Constant Speed.
I'd say that ruled out ground adjustable props like the one in the link.

Also, the description of that propeller is different from a wood composite. "..manufactured using an internal pressure, closed mold system to produce a hollow, one piece blade.." It would at least need a wood core to be considered a wood prop.

I get that it's not a wood prop, so it would need field approval or STC. As far as the adjustable part goes, there was a ground adjustable prop from hartzell on the tcds, so it would seem that the adjustable part wouldn't be too hard to sell to the FSDO? Just gotta see how they feel about carbon...

I have the Sensenich Carbon ground adjustable on my RV 7a. I absolutely love it. I'm not sure if it is FAA approved, but I can highly recommend it after 250 hours of flight.

Here's a pic: