Good Morning Jason,

Thank you. I of course agree completly that for some reason the MU-2 seems a heck of a lot louder than the Merlin/Metro series. I currently have a 226T with -10s and previously had a 26AT with -6s, both of which are used on the MU-2 series. The props on both planes are 98" Hartzells with a 100% of 2000RPM. This is referring to all of the three-blade versions, the four-blade, reverse turning engines are of course quite a bit slower, although the core engine speed is the same. The blade profile may be slightly differant between the three-blade prop models used on the 226 vs MU-2, but I would have to dig out the books to know for sure. By all outward appearances you would think that the planes ought to make the same amount of noise, but they sure don't seem to. I would venture that it has more to do with the physical orientation and installation positioning of the engines on the airframe than it does with any differances between the engines and props themselves. Your guess is as good as mine!

You're also right about blade angle changing and I should have stated that a little better. When the engines are truly at "ground idle" then the blade angle is virtually flat, but the power lever does directly control blade angle while in beta range, thereby allowing the pilot to modulate thrust from the props. There is no "ground idle" stop or gate so power lever position is somewhat theoretical for that setting, and can vary significantly due to engine rigging.

John IV

Interesting thread. I'll just quote this so "I" can come back and read it weekly...if not more !!!!

I concur.

The noise signature is different and it isn't the intake arrangement since that is universal on all TPE331.

I think it has to do with exhaust length, routing, and underwing/overwing. The short exhaust on the MU2 and being under the wing make it louder.


There is a ground idle gate on the MU2 (and another one at flight idle).

Mike C.

Here's a MU-2 going into a grass field in Brazil somewhere. He obviously uses some beta to get things stopped, but when he's still in beta, he pulls the condition levers back to coarse pitch. Is this normal for this type? And why not leave them in fine pitch? Is it so that when he shuts down the blade stops faster?

[youtube]http://youtu.be/zOlvJ7Xnvd8[/youtube]

Looked normal to me. High speed for beta use, he brought the speeds back when he was mostly slowed down.

On the MU-2, Beta mode is anything below flight idle. Beta does NOT equal reverse pitch. In the video, it appears he is at ground idle when he takes condition levers from take-off to taxi mode which is exactly what you would do. You taxi at the lower rpm/condition lever setting....go to TO immediately prior to taking runway, the ignites to auto. On exiting runway, igniters to off, condition levers to taxi....

Notice the "approved" checklist in use?

Terrain warning is annoying, especially for passengers...

1 minute to cool down, -shut down?

Nice video, smooth operator. Thanks for posting.

It is shocking how fast you can stop an mu2 if you use full reverse. I have only used it once outside of training. Tends to throw people into the front. Just going to ground idle (beta) feels like you throw out a boat anchor.

Typical landing is wheels hit, power levers to ground idle, igniters to off, condition levers back to taxi. Rarely do I need to even touch the brakes.

That's not short.

This is short:

https://www.youtube.com/watch?v=7s4GcQB6YyQ

Under 800 ft on pavement (with brakes) and under 1000 ft on grass are no problem. It is the takeoff that limits you on runway.


In beta, the condition lever sets idle RPM, not blade pitch.

In beta, the blade pitch is controlled directly by the pilot with the power levers.

You'll figure this out when you get to fly your airplane. A TPE331 engine course is recommended.

Mike C.

Here is that same Brazilian grass field and plane/pilot. Impressive how he stops it in a short distance. Getting out, is obviously the key though.

[youtube]http://youtu.be/qc0j_0qFukY[/youtube]

I have a question about the terrain awareness for MU-2 operators - I have watched several MU-2 videos and it appears to be common for the terrain warning to be going off incessantly during the landing phase and either pilot's are disregarding it, or there is no way to silence it. Is this normal? If the terrain system is always going off like that, I would think it has the potential of creating a habit of disregarding TAWS warnings over time which might not be ideal? Could this have been happening during Pascal's accident?

Be careful with reverse pitch. It tends to throw the small stuff up in front and pock-marks your blade tips...

Can attest to this! I wish I had a video of the landing at DKX that Mike C. gave me. He easily made first turn off on RWY26, 1000' from numbers to turn. Probably a little hard on the brakes, tires, and props.

Jim

I don't want to start another MU2 thread but most of this one dates back to 2013. I've been evaluating the Aerostar 700SS and the 421C (yes I know it's apples and oranges, but humor me) and about every fourth post is someone pushing me to go turbine. Many insist ops costs/nm are going to run pretty close. I think Mike C and Craig H have made the transition but I'd like to hear from more folks who have made the change from pressurized piston twin to turboprop (twin only) and had both for long enough to forward solid figures on them.

What are problem areas (big $$$) on the MU2? I see some older or less powerful ones that are potentials but are coming up on HSI. How bad can that get?

I think there's a prop inspection issue as well on the four blades but not so on the three blades. Is that correct?

I live a short drive or really short flight from Tulsa so that's a plus maintenance wise. After I get enough education here to ask some intelligent questions I'm planning to go over to Intercontinental Jet Services and hopefully find someone who will further my education.

Alright, you yahoos got me thinking about this. Now give me some data.

5 year inspection AD on 4 blade props only. This inspection did not require but an overhaul but it was often done anyway. The amount of material ground off the props meant the blades ($5,000) had to be retired after 3-4 uses. So about 20 years after the AD was issues a lot of people bought $80K of new blades

Now

1) people more often inspect rather than overhaul
2) there's a 7 year AMOC extension that is newly available
3) there's hope the AD interval will be extended or just done away with (AD stemmed from an issue that has been fixed)

I don't qualify for having had the MU2 very long but here is what I can tell you. I have an F model that has about 1000 hours before TBO on each engine but 1400 and 1200 before HSI. To complicate things further, one of my engines is a 3600 hour TBO and the other is a 5400 TBO. On the 3600 hour engine, at 3600 I am required to do a GBI (gear box inspection) which will extend the TBO to 5400 hours. Some say that TBO on a twin turbine is required while others do not agree. I wont argue that point here but I will say that ALL inspections are required. I personally wouldn't overhaul an engine with a bunch of time remaining before the HSI was due. I have been told that the high end on a GBI is about $40k, low end $20k. Anyway I slice it I will incur large engine expenses in 10-12 years give or take. If something major breaks, it will be more sooner but that's a pretty slim possibility given the reliability of the turbines. It'll cost $100k per side in 10-12 years, maybe a bit more. I don't think an overhaul would ever be a financial consideration when you can swap an engine for one with a 1000 hours remaining or so for $75k installed which gives me another 10-12 years.
100 hour inspections are about $4k plus whatever is broken. I think $10k covers it easily.
Mine has 3 bladed props with no inspection required so $20k every 15 years maybe if that?
200 hour inspections are another $3k flat
600 hour inspections are another $4k flat

So....Numbers annually:

$20,000 (engine reserve)
$4100 Insurance
$9400 Hanger
$5000 Training
$10,000 MX avg.

Fuel is $3.50 x$ 65/hr. x 100 hours = ~ $23,000

Total = $71,500

Round up to $75k or $80k for stuff I left out and what your left with is:

Pressurization, AC, 260kts, FL200 - FL250 for 100 hours.
Lines up with everyone else estimate of $700-$800 per hour.

Here are the things that I have fixed on my plane so far this year.
Replaced wiper motor ($300)
Replaced auto climate controller ($500)
Repaired main door seal - no cost took about 30 minutes.

I have never owned a 421 or any other pressurized twin but its hard for me to imagine one could do it for much less. The MU2 is a tank. Its so robust its hard to explain. Just go sit in one and then go sit in anything else and you'll get it. Better yet, go fly in one through some turbulence. Its a blast to fly. Hope this helps. I'm sorry there are not more planes like mine out there and readily available for people wanting out of a Baron size plane.