MT Prop For A Cruisair

bdon661

bdon661

New member
I'm in the process of building up a fresh (standard crank and bearings) 165 Franklin for my 14-13. After contemplating the problems I've had with the setup and support of my F-200 Aeromatic prop - and contemplating the reduced performance of a Sensenich - I've decided to look for a viable replacement to the Aeromatic. I reached out to MT Propellers to see if one of their electric (think 'early Bonanza', and you'll get the idea) constant speed props might be compatible with the 165 Franklin.

After a lot of back and forth with their engineering team in Germany, we have determined that their MTV-20 series two bladed constant speed prop (wood blades, metal hub) would be a very good match. I have submitted the required technical data - with MT's support and the support of a very good DER- to my local FSDO for a 337 Field Approval for this prop on the Cruisair. The initial response has been positive. The MT prop is not cheap, but it comes with a new spinner and backing plate adapted to the stock Cruisair cowling and it will mate up just fine with the engine and airframe. The projected weight is 2 pounds lighter than the Aeromatic; the electronic pitch control / governor setup works within the confines of the existing cowling and crank flange and the prop control fits in the stock instrument panel. It will be another 3 - 6 months before the new 165 is ready for the airplane and the MT prop will hopefully be approved at about the same time. I'll gladly share my 337 and performance results with the group. This is not a low cost alternative to the Aeromatic, but I think it will be a good match that does not require alterations to the cowling or airframe. If any of you are interested in this setup, please call me. There are not enough airframes to justify an STC, but a generally accepted Field Approval appears - at this time - to be completely viable.
 
I do love my Aeromatic but it certainly is a bit of a tempermental item that seems to take up a lot of time over a long period of time. It too is not inexpensive to keep flying. A lot of fiddling and three trips to a shop in 29+ years; not cheap. I thought of an MT a few years back but never got further than casual talk at AirVenture. What's a "ballpark" when you indicate it will be pricey?

Scott
N74432
 
I will also be following this closely.

Is there a reason you went with wood blades instead of metal? Were metal blades not available?

I posed the question about an electric C/S prop for the 165 a few months back, and here is my answer!
Can't wait to see it in action!
-Adam
 
Scott & Adam:

Thank you both for the replies. The price is going to be 'around' $8500, which includes the prop, a new spinner (composite), a new backing plate (composite), the cockpit control (a knob and a switch - fits in an opening approximately 2" tall x 3" wide), and all the paperwork. During the brief period the Tarvers were producing Aeromatic props with new blades, the F-200 was priced at $4995, so the price difference is significant - BUT to eliminate the constant adjusting of the prop and make the Aeromatic stigma go away without reducing the performance of the airplane is a relative bargain.

Regarding my own Aeromatic, I've simply had enough. I have to fiddle with it all the time and the setup still isn't quite right. I've experienced a backing plate crack in flight. The backing plate and spinner themselves are problematic. I have offered Glenn Tarver a round trip airline ticket, a room at a nice hotel, a rental car, and $500 / day for his labor to come out here and get the prop 'right' and he always has a reason for not accepting my offer.

Regarding blade material choice, MT already produces a two blade 'natural composite' (wood) electric constant speed prop that is STC'd for the Grumman Tiger. The prop I'm having them make is a variation of this existing prop, with an obviously different flange.

I am building up a 'fresh' 165 Franklin for my airplane, so the prop will be installed when the new engine is done. I'm anticipating 6 - 9 months before it actually flies and will gladly keep the board apprised of my progress and results.

Best Wishes,
Brad Donner
NC86916
 
Thanks for the info!

As an aside, the wonderful people at the Franklin Aero shop in Virginia mentioned that a 220 crank (which a new production can be purchased) fits right into the 165 motor. There is no distinguishable advantage besides being able to buy a new crank, and it also leaves an additional 1/2" gap in between the prop flange and nose bowl.

One thing I noticed is that is has a different bolt pattern, with more supportable C/S type props available for it (mostly because the 220 frank was on the Maule).

So my question would become, is it worth it to switch to the 220 Franklin Crank in a 165 (during an overhaul situation of course) in order to be able to utilize the different prop options?

-Adam
 
Adam, I wasnt aware that new 220 cranks were available. That is good news. Brad might want to ask if having a standard 6 hole crank would lower the cost of the MT? A yellow tagged 165 crank sells on the used market for almost the same as a yellow tagged 220 crank. Do you know how much they are asking for a new 220 crank? This could be a real good thing. ____Grant.
 
I lucked out on my 165 core - it had 407 hours TTSN and the crank was 'fat' within the dimensions for standard and required only light polishing (no grinding), so I'm happy with what I have.

Regarding potential lower costs for the MT with a 220 crank, I'll ask MT - it's a very good question. As far as options for a hydraulic (oil pressure) constant speed prop like a McCauley, my preference is for the MT. It's much lighter (35 pounds), doesn't require an oil driven prop governor, and the new spinner from MT will match exactly the profile and dimensions of the original spinner. In other words, the electric MT doesn't alter the weight or appearance of the airplane, which was one of my goals in seeking out a replacement for the Aeromatic.
 
http://www.southernaero.com/index.php/about/

Not sure on the price for a new 220 crank. Try calling southern aero.

-Adam
 
Larry:

You're not left out at all. You've made several posts that expressed your philosophy that we're all just temporary caretakers of an airplane that will hopefully outlive us and be passed on to the next generation. It was that very thought process that led me to the same conclusion you have articulated - the $9k on a modern / well supported / hopefully good performing prop is just a drop in the bucket.

BTW, when I submitted all the tech data to the DER for the field approval, I submitted two sets. One for the 165hp engine and one for the 150hp engine. My airplane still has the 150 Franklin and is still flying while I'm building up the 165. If some disaster should befall the 165 before it's done, perhaps the prop can still be installed on the 150hp engine with the caveat that the low pitch stop has to be set for the lower (2600 versus 2800) max RPM of the 150hp engine. If a single prop works on both engines, I don't mind in the least bit doing the paperwork for field approvals on both engines. I have 337's approved for my Fairchild for all kinds of goodies that haven't been installed yet and may never get installed. To my knowledge, there is no drop dead date on them and I figured it was best to seek and hopefully obtain approvals for things I might want or need in the future while I still have access to a relatively accommodating FSDO.

Best Wishes,
Brad Donner
NC86916
 
Well, this is all very exciting. I like the AeroMatic but have always been slightly put out with the constant " just needs a little tweaking" associated with using it. I've dealt with it since the days of John Buck through Kent Tarver and can never fault the enthusiasm or cooperation of the shops but it's frustrating to always have it not quite right. I wouldn't mind (gulp) $8,500- $9,000 to get a truly matched C/S on the airplane; I REALLY like the idea of a spinner that conforms to the original profile and hence leaves the airplane looking original. I'd also keep the Aeromatic, and the boxes of information/correspondance I've accumulated for whoever the lucky SOB is that gets my plane..... Hey Chris, are you out there?

I flew a friend from Hillsville, VA (HLX) to Jacksonville, NC (OAJ) yesterday (sound familiar Adam?) for business and once again realized that at 83' MSL my 165 with the AeroMatic will turn in excess of 3200 RPM on T/O if I don't pay attention to it since it's set up for about 3,000' MSL here at HLX. Summer DAs are routinely 4,000' to 5,500'. Two mildly overweight guys, full tanks, about 35# of "stuff" in the baggage compartment and about 80# of briefcases, coats and other goodies on the back seat and we still were getting about 800 FPM climbing through 7,500'. A strangely beautiful day and a pleasant 3.9 hours with a gph of 8.8. It doesn't get much better! Oh yeah, the friend payed for all the gas too.

Anybody going to be at Sun-N-Fun? I'll be there Wednesday night through Sunday morning, sans Bellanca, and would love to meet. 276-237-0464.

Scott
 
800 FPM at 7500 feet sounds wonderful. What RPM were you still turning at that altitude? The normal flattening out of the climb with the Aeromatic at altitude is what the HI-CRUISE option was all about. It used oil through the crankshaft to make a piston mounted on the front of the hub flatten the pitch to keep the RPM up when you start loosing manifold pressure from altitude. Any Aeromatic could be modified to a HI-CRUISE with just one hole drilled in the hub and the right parts put on the front of the prop. It required an oil control valve on the side of the Franklin case and a drilled crankshaft. The 165s had the case set up for the valve and all came with the drilled crank. There used to be factory paperwork to modify 150s for the HI-CRUISE but it (like too many things) has been lost to history. Kent doesnt want to deal with them because he says he cant find the oil control valves. I think the HI-CRUISE would be great and I assume much less than $9K. I have had all the parts to modify mine, but I never got around to putting my 165 into the plane, so it didnt happen. I dont know if Kent has the installation drawings for things like the cockpit control and how to lead the cable, but it is not difficult to do. In theory it should only require a log book entry since it is in the TC. I doubt that there is an FAA guy alive that has ever dealt with one. OOPs, I am getting too long winded again. _____Grant.
 
Amazing! I just looked at Barnstormers for the first time in a while and there is a HI-CRUISE for sale. It is the wrong blades for a Cruisair so at the price it would not be worth buying for the parts to put on one of ours, but it is interesting. ____Grant.
 
Can't swear to it but probably about 2650 to 2700; I can usually get about that in cruise and I typically cruise between 5,500 & 8,500 when not local. The terrain isn't too off field friendly here so I like altitude to increase options and give me time to prepare.

Scott
 
I think that is the secret to getting more altitude out of an Aeromatic. Keep it at or close to red line for the max HP. That is were the H-C altitude control would get the prop beyond its normal range for whatever field altitude it is adjusted for. It is a shame that so many good ideas from the past are not available now. It reminds me of all of the old STCs that belong to dead people or unlocatable people , so you cant get permission to use them. _____Grant.
 
Scott,
I guess the most unbelievable part is that you are doing some kind of business out of jacksonville, NC! Last I saw, there were only a few run out line birds at KOAJ.

I think that C/S prop performance is probably obtainable if an aeromatic is "perfectly" tuned. The problem is that it seems almost impossible, and quite expensive to get that performance from an aeromatic.
So as an option to those are already rebuilding an engine, the cost / benefit comes into play. A perfect world has a C/S prop that fits a 220 franklin crank with metal blades.
Then when rebuilding, you could shell out the dollars for a true C/S prop with a factory new crank, with metal blades that would last forever
-Adam
 
It is interesting that the HI-CRUISE is adjusted with a wrench. Of course you set the static with the weights off, but you dont take the front cover off and change shims, you adjust with a wrench. The flying part of the adjustment is the same as the regular Aeromatic, except that when you start loosing RPM at altitude you use the control to flatten the pitch and bring your RPM up to a more powerful range. I have never flown a HI-CRUISE but the adjustment procedures are not that much differnt than a regular Aeromatic. It should be doable. Just my 2 cents worth. ___Grant.
 
Well, I agree wholeheartedly. But then again it is a piece of 1940's equipment and was pretty cool stuff then. It annoying but workable. I have used authenticity as one of my self congratulatory reasons for not upgrading to a more modern engine/propeller set up. But then again I made my living flying pretty sophisticated military and civilian toys and ALWAYS used my GA flying to indulge my childhood fascination with old-Neato-retro airplanes. Although the Cruisair "only" muddles along at 140 or so mph, getting there's a lot of fun too.
 
Scott,
Regarding your last sentence...

Fast airplanes are for people that don't like to fly!

That's my rationale and I'm sticking to it!
 
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