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How badass is one plane allowed to look? (MU-2)

Sometimes more blades means a better ground clearance.

On a TB20, the 3B prop gives you an extra 1" (25mm) over the 2B prop. Zero extra performance (less than 1kt difference).

The ground clearance with the nose gear fully compressed (i.e. what you get when dipping into a depression in the ground) is 5" (125mm) on a 3B prop and losing 25mm from that is less than ideal.

Administrator
Shoreham EGKA, United Kingdom

We have the MT 4 blade prop which seems to have similar blades to the one on the MU-2. Jason is right there is no performance gain. The advantages are:

- At each overhaul the blades get remanufactured to new dimensions. So you do not grind them down until the blade has to be disposed.
- Reduced exterior noise for countries where that matters. At Friedrichshafen we now pay only half of what we used to pay with the old 2 blade propeller
- More ground clearance and reduced shock loading in case of light ground strikes. As we recently saw on that DA42 the blade tips will just shear of.
- In fact the MT prop is competitively priced compared to other new propellers

So Jason is right. We needed a new propeller and I would buy it again. But I would not throw away any perfectly serviceable propeller just to get the MT.

www.ing-golze.de
EDAZ

My SR22 will be upgraded to the MT MTV-14 4-blade prop in February.
I have talked to 3,4 SR22 owners who already have it and this seems to be the facts:

- Better acceleration on take-off
- much less vibration and less noise, sounds “almost like a turbine” (:-))
- better cooling
- Same speeds as Hartzell 3-blade
- about 1 inch more ground clearance du to shorter blades
- like the ones on the MU2 the newest version of the MTV-14 can be had with full length NICKEL protection, I ordered that
- one of the best thing: pull the power back and you have a very strong braking effect and much higerh sinkrates are possible, shorter landing roll too
- price approx- $ 16.000 including TKS and polished spinner

The negative point: even with the MTV-14 i will not get a noise certificate for the SR22 …

Last Edited by Flyer59 at 31 Oct 11:11
On a G-reg you have a mandatory 6 year overhaul

The MT props are not lifed, and I would assume that’s the case on a G-reg as well?

EGTR

Hartzell has now also invalidated the private ops beyond TBO (kalendar) for a variety of their props, which is why I have to overhaul my prop every 6 years now regardless of the time actually flown.

I have checked if I can exchange it for some other make which does not rip of their customers like that, but unfortunately for the M20C there is no alternative. MT can only provide props to the E-model or higher.

LSZH(work) LSZF (GA base), Switzerland

Achima, I currently own and maintain 12 (twelve) vehicles that were designed and built outside of the US after 1950, including one aircraft. All are for my own use.

The MT prop is an old design, not a bad design, but it could be improved. Whirlwind started down that road 20 years ago when the founder (a friend) left university. His first props had many of the same features but now have hollow, strong carbon fiber blades with more efficient shapes, better blade retention, and hard nickel leading edges that don’t corrode and fit the blade perfectly because the tools for each are made from the same CAD database. A key feature in that development is there being a conscious decision to avoid the certified market and it worked because he does a good business, selling a lot of props to people who chose his over the certified options. I think certified props, more so than engines, could benefit from what has been done for experimental aircraft.

@Mooney Driver, is the ‘mandatory’ Harzell overhaul cycle made mandatory by an A.D?

Last Edited by Silvaire at 31 Oct 15:20

In fact, I doubt there is such an AD.

Hartzell has now also invalidated the private ops beyond TBO (kalendar) for a variety of their props

I guess Hartzell has done nothing. Maybe certain CAAs (possibly the swiss one)
have taken a new ruling on how certain manufacturer “instructions” are to be implemented, but that’s a totally different story.

Last Edited by boscomantico at 31 Oct 15:24
Mainz (EDFZ) & Egelsbach (EDFE), Germany

Silvaire,

I asked and it is actually a service letter which was updated in 2013. I was informed last year that this change had been issued by Hartzell, the same thing was comfirmed to me by the overhaul organisation, which is MT propeller with whom I discussed if there was a way to exchange from Hartzell to their product. I talked at lenght with one of their experts in Friedrichshafen last year and he told me the exactly same thing. He was extremely helpful and also gave me valuable hints on how to minimize the cost of the required overhaul.

Last Edited by Mooney_Driver at 31 Oct 16:13
LSZH(work) LSZF (GA base), Switzerland

No, I can attest that Hartzell is the devil. They force more SB’s into AD’s than any other prop manufacturer. And if you have a rare type, or unsupported, they will stick it to you good (because they know the numbers won’t get heard).

On the Commander they had a 250hr SB and that they pushed hard to get to an AD with the FAA. On top of this they had a 500hr AD. As FAR part 91, I have the option to not comply with SB’s. Problem is that any prop shop has strict mandates that if they want to remain a Hartzell maintenance facility, and get parts and supply, they have to treat the 250hr SB as an AD. Just vile behaviour. I finally got it done somewhere where they ignored the SB. Aerostar is the same. A few years ago they invented a new hub. All of a sudden the old hubs were susceptible to a recurring AD unless you bought their new V-hubs.

So if there’s any way of getting away from Hartzell, I’d take it.

172Driver – I wish! I love MU-2’s. Built like little fat bricks.

Last Edited by AdamFrisch at 31 Oct 16:14

Oh, just one more..

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