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201 MT Propeller pirep


Tim Jodice

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  • 2 weeks later...

PI finally recorded the sound levels. 

I was not at 9500 feet today but in the future I will do an apples to apples comparison. I didn't take pictures of the original prop so you will need to trust me on those numbers:wub:

This does not look that impressive but the perceived noise is so much better. Maybe some education for me on how measuring sound works? @carusoam please help with the orientation of my photos:)

OEM McCauley
Idle 1200 80 db

Take off 103 db

Cruise 

9500' 2600 RPM 97 db
2200 RPM 87db

MT prop

Idle 1200 78 db
Take off 96
Climb 2700RPM 2000' 96db

Cruise 7500' WOT

2700 93.8 db
2500 92.2 db
2300 89 db
2100 89 db

Decending

2000 RPM 23" MP 91 db 
1200 RPM 17" MP 82.5 db

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If you want to protect your hearing, wear a headset or ear plugs if continuous sound level exceeds 85dba.  

This war has been won as there are multiple noise reduction (in ear/over ear) solutions for GA cabins.  

Get a six cylinder engine as vibration is the ultimate enemy...and use oxygen if you fly high.  Hydrate.  Drink water or sugar free sport drinks before, during and after flying.

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1 minute ago, Missile=Awesome said:

If you want to protect your hearing, wear a headset or ear plugs if continuous sound level exceeds 85dba.  

This war has been won as there are multiple noise reduction (in ear/over ear) solutions for GA cabins.  

Get a six cylinder engine as vibration is the ultimate enemy...and use oxygen if you fly high.  Hydrate.  Drink water or sugar free sport drinks before, during and after flying.

That all makes sense. What made you post it here? 

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Loudness measurement is interesting.  I am not an audio specialist so I'll defer to the experts.  That said...

Loudness is largely a measurement of how your ears will perceive sound energy.  Our ears are not linear, so to provide a useful measurement the meter has to first measure the sound energy of each critical band (of frequencies), then simulate the relative sensitivity of the human auditory system by applying a different "weight" to each band.  Once done, it then just sums the weighted energies of all the bands and converts to dB (notated as dBA on the meter since it is using the "A" weight curve).

Note that the "A" curve, while not entirely accurate, is highly correlated with occupational risk of hearing loss.  That makes it very useful for determining which prop is going to hurt your hearing the least (better have hearing protection with either!).  It does not, however, do a very good job of telling which prop is going to be more pleasing to the ear...

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14 hours ago, Tim Jodice said:

That all makes sense. What made you post it here? 


One of the cool things about MS... Other than the Mooney thing...

Everyone has another part of their life they are equally familiar with... and dedicated to...

Scott @Missile=Awesome (Iirc) has a background in industrial safety... or something similar... (based on fuzzy old memories)
 

When it comes to hearing protection, and things in Iowa... Scott’s our go to guy... :)

 

Tim,  thanks for putting in so much effort to collect and share data... these pics are spectacular...

Best regards,

-a-

 

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  • 2 weeks later...
  • 2 months later...

Update on the MT prop. It has about 200 hours on it, it parks on grass every day and files in the rain. In my experience so far it seems that they have fixed the issues of the composite/paint separating in rain. 

As you can see the tip is barely showing wear yet the rain was hard enough to strip the boot adhesive inboard.

Not that I expected the adhesive to be durable but considering how far inboard it is, how much slower it hits the rain and that it is completely cleaned off the leading edge I think demonstrates that the tips were going through some hard rain.

Still in love with the prop. If I had to change airplanes it would be the first thing I upgrade on the new one.

20210105_072138.jpg

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It seems like MT has improved over the years.  When I did my rebuilt I considered the MT.  I spoke with a Power plant DER who had been working on seaplanes that had MT props and were experiencing a delamination problem.   I was also told that the STC for my turbonormalizer was issued with the Hartzell, and if I changed the prop I would likely have to prove to the FAA that it worked well with the turbonormalized engine.  That would likely require high altitude vibration testing.  I decided to stay with what was already certified and not make the project more difficult.  That seemed to be the right decision in 2006.  Is it still likely to be the correct decision in 2021?

John Breda

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  • 1 year later...
On 10/1/2020 at 8:10 AM, Tim Jodice said:

PI finally recorded the sound levels. 

I was not at 9500 feet today but in the future I will do an apples to apples comparison. I didn't take pictures of the original prop so you will need to trust me on those numbers:wub:

This does not look that impressive but the perceived noise is so much better. Maybe some education for me on how measuring sound works? @carusoam please help with the orientation of my photos:)

OEM McCauley
Idle 1200 80 db

Take off 103 db

Cruise 

9500' 2600 RPM 97 db
2200 RPM 87db

MT prop

Idle 1200 78 db
Take off 96
Climb 2700RPM 2000' 96db

Cruise 7500' WOT

2700 93.8 db
2500 92.2 db
2300 89 db
2100 89 db

Decending

2000 RPM 23" MP 91 db 
1200 RPM 17" MP 82.5 db

 

 

Just wondering if it was a typo, but it looks to me in cruise that the sound levels are slightly louder with the MT than the McCauley.  Did you perceive this when flying?

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18 hours ago, FlybyNite said:

Just wondering if it was a typo, but it looks to me in cruise that the sound levels are slightly louder with the MT than the McCauley.  Did you perceive this when flying?

Not a typo for some reason the lines crossed at about 2300. maybe because I did the stock prop at 9500 and the engine is making less power. The perceived noise level is unmistakably lower at all but lowest RPMs.

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1 minute ago, Tim Jodice said:

Not a typo for some reason the lines crossed at about 2300. maybe because I did the stock prop at 9500 and the engine is making less power. The perceived noise level is unmistakably lower at all but lowest RPMs.

Are you still happy with your decision to go with the MT?

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59 minutes ago, John Mininger said:

Are you still happy with your decision to go with the MT?

I maintain several dozen planes locally, that have a mix of Hartzell aluminum, Hartzell composite, and MT composite props. We overhaul the Hartzells when we change engines at 2000 to 2400 hours. Otherwise, they need very little care. 

None of the MT's make TBO. For example, I overhauled one 18 months ago, due to a cracked leading edge and extensive lost filler, and it now has 1100 hours on it. They installed MT factory overhauled blades to save down time. I spend a few hours per month filling in lost filler behind the leading edges. And re-bonding the trailing edges where the cover separates. It leaks grease, and of course, there are no fittings to re-lubricate the hub. I have another one that las less than 600 hours since new on it, and it's been back for repairs twice, and it's leaking grease again. My hangar neighbor put a new MT on his Cessna, and it's not a year old yet. The spinner bulkhead cracked behind all three blades. He has to put his old prop back on while MT fixes his new prop. 

But I do think an MT prop would look great hanging on the wall as a decoration. They look pretty.

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25 minutes ago, philiplane said:

I maintain several dozen planes locally, that have a mix of Hartzell aluminum, Hartzell composite, and MT composite props. We overhaul the Hartzells when we change engines at 2000 to 2400 hours. Otherwise, they need very little care. 

None of the MT's make TBO. For example, I overhauled one 18 months ago, due to a cracked leading edge and extensive lost filler, and it now has 1100 hours on it. They installed MT factory overhauled blades to save down time. I spend a few hours per month filling in lost filler behind the leading edges. And re-bonding the trailing edges where the cover separates. It leaks grease, and of course, there are no fittings to re-lubricate the hub. I have another one that las less than 600 hours since new on it, and it's been back for repairs twice, and it's leaking grease again. My hangar neighbor put a new MT on his Cessna, and it's not a year old yet. The spinner bulkhead cracked behind all three blades. He has to put his old prop back on while MT fixes his new prop. 

But I do think an MT prop would look great hanging on the wall as a decoration. They look pretty.

Interesting observation. I am responsible for all the maintenance on 47 flight school aircraft (40 Diamond DA 40s, 5 DA 42s and 2 DA 20s) with over 100,000 fleet hours that are all equipped with MT propellers and I bought one for my Mooney. 

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On 9/21/2020 at 8:11 AM, Tim Jodice said:

I have 60 hours on the prop now and thought I would update how it is doing.

It does help cooling a little. It took about a dozen flights to consistently see a lower temp so I knew it wasn't the variables like temp altitude weight etc.

It really doesn't have a sweet spot RPM regarding vibration, spin it faster if you want to go faster. I have tried that from 2000-2700 

I had the opportunity to fly through some rain and the pictures show that they have fixed the paint peeling issue. The rain was hard enough to take the boot adhesive off close to the hub but no problems at the tip.

Like most say about Mooneys I want to go fast so unless I am below 5000 I almost always have it at 26-2700 RPM in cruise. 

I am still experimenting with coming down. When I am VFR I like trying to be efficient coming down so I try to time it so I come down at cruise IAS of about 140. With the 2 blade most lower (2200 down) RPM was not very smooth. I have found that 1800-2000 is a nice RPM for coming down.20200921_071530.thumb.jpg.0972c1bc70568901650c13208bebae40.jpg

 

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There’s no experimentation requirements for  coming down, simply roll the nose forward and trim for a 500 foot per minute descent.. the IAS increases by about 30 kn but it’s still at the top of the green arc, and take the benefit on the descent to offset some of the penalty for climb

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