Seneca: McCauley or MT propeller?

prop stands well clear of the ground and less prone to damage

Yes, but with only about 2’ 6” clearance I still didn’t do engine run-ups on gravel.

It was cracks in the trailing edge of the fibreglass skin at the blade root which annoyed me most, although of no structural/warranty significance according to the factory.

Jacko wrote:

I flew for about 500 hours with an MTV-15 prop on an O-360 powered Maule

Tailwheel? If so, prop stands well clear of the ground and less prone to damage.

I flew for about 500 hours with an MTV-15 prop on an O-360 powered Maule

Pros:
Light weight and low inertia = great throttle response
Slightly better performance than the original Hartzell prop
Good after-sales support (which is needed)
It’s easy to fix cracks, blisters and chips in the fibreglass skin with 5-minute epoxy glue
When you flip your Maule onto its back the prop breaks and saves your crankshaft

Cons:
The description “natural composite” seems a bit of a con. It’s wooden propeller with a thin GRP skin (which is not shy of cracking and separating from the timber core).
My maintenance organisation (also a propeller service station) won’t touch them.
It seems expensive for a wooden prop.

I wouldn’t rush to buy another MT. Will probably try a Hartzell Raptor instead. YMMV.

I have never damaged an MT prop (’can’t say the same for metal :( ), but that said, aside from flight testing them for approvals, I’ve done most of the operation on floatplanes and amphibians, so stone damage is hardly a risk. Metal prop erosion of floatplanes is a problem with careless splashing, MT’s survive that much better. MT allows epoxy repairs, indeed, stating “fill void with 5 minute epoxy and sand.”, which is a happily casual repair. Even the leading edge may have an epoxy repair if it is not punctured, or delaminating.

Some airplane types are simply vulnerable to prop damage, as they are close to the surface, and there is little opportunity to “keep the props light” during run ups. As we do have gravel runways and run up areas in Canada, I’m vigilant about propeller care. No runups over loose ground ( see :( above, lesson learned). When I bought my Cessna 150 34 years ago, I bought it knowing that the prop had been dressed near the minimum limits already, so to take the best care, so as to delay having to replace it as long as possible. 3000 hours later, so far so good, zero blade dressing on it!

But I agree that some twins just do not afford the opportunity to keep the props light off the surface, and do require longer run ups, so the risk is higher. The aforementioned DA-42-L360 I was testing was “borrowed” for a couple of days to be flown to a show. It was a couple of days late being brought back to us. It had left to the show with MT’s and came back with Hartzells. I heard a grumblings about someone damaging props doing a run up on the way back to us.

Experience with the type (I’ve never flown a Seneca) should enable understanding the risks of tip damage. My expertise is that with the prop tips seven feet off the ground on my amphibian, or careful operation on a 150, you can fly a long time with no tip damage!

Antonio wrote:

With the MT, you almost always have to remove the prop and send it to shop, leaving you grounded for weeks and incurring a much more expensive shipping and repair fee.

Do you have a different experience?

Yes. I had blade damage on an MT Prop, on the ground (engine not running). My mechanic came with some kind of (epoxy?) glue, did the repair on site, and after some time (can’t remember if it was one night or like 3 days) to let the glue “set”, the plane was good to fly.

Thanks @PilotDAR.

The big difference we have seen is that for minor nicks and dents, any mechanic can do a blendout on a metal prop and you are back in service the next day.
With the MT, you almost always have to remove the prop and send it to shop, leaving you grounded for weeks and incurring a much more expensive shipping and repair fee.

OTOH, you get more and deeper dents on the MT’s not to mention of two instances of LE release I am personally aware of.

Do you have a different experience?

I like MT props, and have one on one of my planes. I have installed and flight tested a number of other installations, with great success. I’m not knocking McCauley, nor Hartzell, but I do prefer MT. Some of my reasoning is that the blades are not fatigue sensitive, and can be repaired if damaged. Generally they result in either a more quite plane, or at least a less “twangy” sound, if noise compliance is a concern. MT offer either a [smaller] stainless steel leading edge, which is good, or a nickle leading edge [more chord] which is more durable and protecting. The nickle leading edge is great to prevent erosion for floatplane use (I’m sure not a factor for a Seneca).

Though gravel damage from careless ground operation is possible (for either prop), the MT blades could be repaired for any damage, the metal blades will have a small tip damage allowance, then be scrap. I’ve seen MT blades, literally broken in half, being repaired in the factory. I did a full STC flight test program and approval for MT props on a Twin Comanche, and did see a performance improvement. Similarly, I flight tested the DA-42-L360 with both the MT’s and metal (I don’t remember which brand), and found the MT’s to be preferred.

One comment about changing from metal to composite, the prop has a lower polar moment of inertia, which means less flywheel effect. This is generally not a problem on a Lycoming, though with a weak starter or battery may mean that you have troubled starts. On Continental powered airplanes, it can be more of a problem, and damage the starter adapter if the prop kicks back (which is more possible with the MT) during the start. I’d still put an MT on Continentals (and have), but be very sure Mag timing is good, and the starting technique is correct to prevent kickbacks.

Rob wrote:

What is LE fragility?

Leading Edge stainless strip dented or mostly released (scary and noisy) after encounter with grass or loose gravel.

I bought a Seneca II last October as my first twin. Since I have bought it, it has always had 3-blade MTs, which were freshly overhauled, dynamically balanced and are de-iced. The previous owner of the aircraft was MT Propeller itself, so that was to be expected. Before, I had a Mooney which also had a 3-blade MT.

I therefore have no comparison, but just the MT “experience” alone, which is: No complaints so far. I am happy with the performance in climb and cruise, compared to the aircraft I have flown while doing my MEP rating and also with the Mooney. I normally cruise at 2200/31.5 inches in the Seneca, which is a lot quiter than the Mooney was and which causes virtually no vibrations. I always use this setting, and have tried it up to FL160.

The MTs allow to have a reduced noise certificate on the Seneca II, altough this is maybe a rather Germany-related improvement, which might not even be available on the Seneca III upwards, as the RPM limit on the II is 2500rpm.

Other small hint: The ampere-meter for the pro de-ice shows lower values on the MTs, so it is out the green arc or at the lower end at least. MT told me this is normal for the MTs. Actual de-icing works fairly well on the props though.

Finally: I took me quite a while to do smooths landings with the Seneca, especially with a forward-CG. People told me, that this is a typical Seneca behaviour, but which is increased by the MTs. Maybe true for any 3-blade Seneca or even Senecas in general. However, I have managed to improved the technique after around 50-60 landings, so this should not be a show-stopper for a decision.

If you have the time or if you ever happen to be in Germany I am happy to show you.