Advice on MT Prop for M20K

[SkyBound]

I am considering buying a 1979 Mooney M20K with a Continental TSIO-360LB-8 and an MTV-12 3-bladed propeller installed in 2003. Both the factory remanufactured engine and the prop have about 300 hours and appear to be in good shape.

Does anyone have experience with this prop in a similar configuration?

Thanks in advance for the feedback and advice.

[thinwing]

I have a 2 blade Mt on my Husky...very smooth and light weight..kpc

[SkyBound]

Thank you ThinWing. How has it been to maintain?

--AG

[KSMooniac]

I put a similar prop on my J almost 2 years ago. It is lighter, smoother, and better looking than the McCauley 2-blade. It is slightly slower in cruise, though, but in your case with a turbo I think it wouldn't matter since you can run higher MP if you wish while I'm limited without a turbo. I think high MP and lower RPM is optimal for the MT as I believe the blades were aerodynamically optimized for efficiency at lower RPMs due to noise concerns in the EU. Getting weight off the nose of a turbo Mooney is a good thing too as many of them need or use ballast in the tail to get the CG in the right spot.

I had severe trouble with paint eroding while flying in IMC with my first blades. They were repainted under warranty, and shed paint badly again. I insisted on some replacement blades and these have been better so far. /knocking on wood.

[KSMooniac]

I'll add that I believe the blade construction is far superior to metal blades... in the event of a prop strike there is a greatly reduced chance of inflicting damage on the hub and engine since the blades will splinter. The stainless steel leading edge is replaceable (by a prop shop) so there should be near-infinite blade life whereas metal blades are usually only good for a couple of overhauls before the contour is too far gone.

[SkyBound]

Scott,

Thank you. The information is very helpful.

--Alex

[carusoam]

Is there any word on outdoor storage of the MT prop? UV or excessive moisture related damage?

The MT site shows an interesting photo of a 4 blade prop on an Ovation. Lighter would be nicer as well.

Best regards,

-a-

[Rustler]

Alex--

I installed an MT prop on my M20J after my original prop sustained substantial rock damage 2+ years ago. The choice was to replace it with a similar 2-blade or to invest in the MT. I could not be happier with my choice.

The MT is eight pounds (+/-) lighter than the 2-blade, which I contend places less strain on the crank shaft bearing at the front of the engine. Probably not a huge amount, but certainly measurable. It is perfectly balanced when it comes from the factory. What is most apparent from the outset is that long cross countries are more enjoyable because of the lack of vibration and a decrease in the sound level; over 4-5 hours, the difference is really noticeable. There can be no harmonic vibration when running the prop because the core is wood and cannot support it. I have had no issues with the finish on the blades.

Almost simultaneously with the prop change,, I did an engine exchange, going from an IO-360A3B6D to an IO-360A3B6, and I do not see any difference in cruise speed. I consistently get 150K true now, the same as I did previously.

[CAMooneyPilot]

I put the MT 3 blade prop on my 1979 K about 18 months ago. It has added at least 200 fpm in the climb, and added 5kts at 18K ft to the cruise speed. I had the Hartzel 3 blade that was on it when I bought the airplane (still have it and would like to find it a good home). I am a believer in the MT. So far, its performed as well or better than advertised. Quieter and smoother that the Hartzel, and I had the Hartzel balanced.

[bdjohn4]

No problems with crazing/cracking of the blade finish. I am forced to replace my Hartzell 3-blade ( on my '69 E-model) and my local trusted A&P/IA, who does a bit of work on Liberty LSA (MT-equipped) says the crazing/cracking on these makes A&Ps leery.

I figure I should reduce as much vibration as possible on this nearly half-century old airframe.

Any thoughts?

BTW: I considered the IO-390 conversion but passed and will just O/H my io-360A1A. $4000 cylinders were just too much to stomach

[bdjohn4]

Forgot the "?" Mark. Are there problems with crazing/cracking in MT props?

[Rustler]

bdjohn4--

 

I never had any crazing or cracking on my MT. Liked it well enough that I'm getting ready to put one on my new-to-me M20K.

[bdjohn4]

OK. Thanks. I spoke to Pete at MT just now. Lead time is 14 weeks unfortunately but he has it on order for me.  Price differential isn't that much when you consider you get a Kevlar spinner with the MT.  No flying this winter though, unfortunately.

[villinger]

I am new to  this forum - I am from Austria Europe.

 

We design ice protection systems for propellers and used several  3 blade MT  propellers on  Mooney M20K´s  for the development. We did over 2000 hours on those Propellors so far in all kind of conditions. No problems at all - they work great and run smooth.

 

Besides replacement de-icer pads our main focus was  to implement the de-icer into the propeller blade for improved aerodynamics (glued on de-icer pads decrease airplane performance measurably).

 

I do not know the performance of the Hartzell 3 blades  Propellers in comparison - however with the clean MT 3 blade (with internal de-icers) a Mooney M20K does 180 TAS on 10-11 gph in FL 180 running ROP and in the temp limits (CHT < 400, TIT < 1550) . The airplane is equipped with intercooler and Merlyn waste gate. This should give you an idea about the performance which we think is very good.

 

If you fly an MT prop without Propeller de-icing and want to get an additional  bit more performance out of it then rip off  the black rubber erosion strips on the inside of the propeller blades - it will give you some extra performance - enough that you should be able to measure it.

 

If interested here is a link to some of the work we do with   Propellers    http://www.villinger.com/index.php?lang=2&hID=24

[carusoam]

Welcome aboard Villinger...

Best regards,

-a-

[bdjohn4]

^{Thanks for the replies. I think I am going to go with the Lycoming IO-390 conversion (STC = SA09695AC ) and thus am limited to the Hartzell Scimitar (2-blade = HC-C2YR-1BF/F7497 , or the 3-blade= HC-C3YR-1RF/F7282 ), but am thinking of going with the 3-blade given the slightly greater ground clearance, fankly (Prop-strikes are, it turns out, very very expensive mistakes). There is no STC for the MT on an IO-390 at the moment, so as much as I would like to put a MT 3-blader on there, I cannot at the moment. I spoke with a close friend that is a FAA DER and Seneca II owner (a pretty smart guy that understands the regs and culture of the FAA/FSDOs), and he says that putting an untested prop on a certified ACFT is more than Field-Approval, that much vibration data must be obtained. I am talking with Pete at MT USA to see if they are interested in doing an STC for the IO-390, but haven't heard back yet.  Sure would be nice to have a lighter-weight composite blade option like a MT for the IO-390}

 

^{I feel that, with the AVGas future unknown, the worst that could happen is that I could have to de-rate the IO-390 to a lower horsepower and running a lower-octane fuel. Who knows what the future may hold.}

[KSMooniac]

The metal 3 blade props for Mooneys are the same diameter as the 2 blade versions, so you get no additional ground clearance. Only more weight, vibration, and lower performance. You also might want to check the price of 390 cylinders too. Sent from my ADR6425LVW using Tapatalk

[jlunseth]

What is an LB8.  Just curious, never seen anything other than the LB1?

[bdjohn4]

I stand corrected on the prop diameter. I could have sworn I read that the 3-blade was 1-2 inches smaller in diameter. I guess I've got a decision to make.

 

http://hartzellprop.com/wp-content/uploads/159-0000-R37-AW.pdf . Page 949 (or M-45)

 

What wold be the real-world difference in cruise performance with a 2-vs-3 blade?  1kt, 2kts? Anybody have real experience with this question?

[KSMooniac]

The MT is the only prop with a lower diameter than any of the current metal Mooney props.  It is also significantly lighter, which can benefit all Mooneys.  Anecdotal tales will say the cruise performance loss on 4-cylinder Mooneys with 3-blade props will be in the 3-5 knot range, with modest improvements in takeoff and climb performance.

 

There is really no good reason to add a 3-blade metal prop except for ramp appeal.  The cost more to overhaul, weigh a LOT more, and typically have vibration issues that cannot be rectified.  

 

I'd also be concerned with those $4000 cylinders on the IO-390.  I'm going to overhaul my entire IO-360 for less than the cost of 4 new cylinders for that thing... (/knocking on wood)