TB20 2 blade to 3 blade prop change

@Shorrick Mk2

Of yourse you may ask but I hope you will understand that I prefer not to answer

My simple reasoning is that the exchange of my prop happened already four years ago in a different economic climate, maybe a very different load situation for MT, exchanging very different props from the ones you might be looking for etc. Stating some number would probably be rather meaningless and therefore misleading and unfair to both yourself and MT.

@RXH if I may ask how moderate was the moderate cash payment for the prop exchange? I am pondering exchanging the 3-blade McCauley vs a 4-blade MTV14 at next overhaul (if only to make the mooney look even more like a mustang).

@ RXH
before I ordered the prop MT told me about these HiGlo problems you mention – however I also ordered it with the chrome layer.
Let’s see how it works. Think I have to brief the A&P urgently not to kick around the spinner when at the annual …

@ nobbi

Which spinner are you planning on getting?

To “sweeten the deal” MT included the HiGlo-spinner when they installed my prop. The HiGlo is their standard composite spinner (which can be painted in any colour) with a chrome cover and some colourless lacquer on top instead of paint. It does look very nice but the chrome cover (NOT the spinner) has developed some small cracks after about 4 years of use in certain areas and also some chips of chrome have come off at the edge of the spinner. The chrome covering of the spinner was not done by MT themselves but some other company they sourced this work to which obviously did not have this process under control as well as they should have.

I understand that MT has come off this particular product a bit and especially for higher powered planes being flown in weather do not actively recommend the HiGlo any longer (don’t quote me on this, this is hearsay I have from a third party). However, when I talked to MT about the cracking chrome cover they offered without any fuss to paint the spinner at the next prop overhaul in a colour of my choosing at their expense. I think this is more than fair.

RXH – would you say that the 3B MT prop has a significantly different braking effect to the 2B Hartzell?

Yes, it does. I made that experience for the first time during the test flight I described above with another TB20 which had the MT 3-blade installed before I made the call to install that prop on my own plane. Over the treshold I reduced the power to idle the way I was used to doing it with the 2-blade prop and the plane decelerated and dropped quite a bit more than I was expecting. The resulting landing was certainly not in the top three of my best landings.

As flyer59 has pointed out, the MT 4-blade prop STC’d for the TB20 has the older design round-tip blades. I asked MT about the 4-blade at the time I was thinking about getting a new prop. They did not actively recommend it and advised to go for the 3-blade prop with the newer design.

I changed prop on my TB20 about 18 months ago. In my case it was from a Hartzell 2 blade metal to a Hartzell 3 blade metal.

I definitely prefer the look of the 3 blade, so have no regrets. But I can’t really say I’ve seen a noticeable difference in performance. Perhaps a little better climb performance, particularly when climbing above 10,000 feet. And I like to think it’s a little smoother, but that’s only a subjective view.

So from my perspective, the change is worth it for the look of the prop, but any performance enhancements will be small.

@ Petakas

are you sure that the governor has a 12y overhaul limit – so far I thought it was also 6y ?
I am in for a prop change with my TB20 to MT9 three bladed – MT need 2,5 months now to deliver. Think they were very busy with one guy’s 4 bladed prop

edited: I just found a reference by Hartzell which confirms the 12y

D. Governors
(1) Hartzell propeller governors are to be overhauled at the same time as engine
overhaul, but not to exceed 2400 hours of operation (there is no calendar limit
applicable to governors).

Oh, i was wrong, sorry. I had asked one of the engineers about the TB20 last week and he said that there’s no STC yet … maybe he misunderstood my question … This one has the old style blades though

i think there is no TB20 STC for the MTV-14 four blade prop yet.

This is said elsewhere to be a 4B prop

And here you go

Only one was ever sold, to the above TB20 owner (D-EACX, at the time in Switzerland) whose plane was used to get the EASA-only STC, and reportedly MT don’t market it anymore.