The 4 blade Hartzell props are very quiet inside. When I ran mine we had another operator we would broker trips to that had a straight III with the 2000 rpm 3 blade props (that airplane also had the -10 conversion on the engines). It was night and day different than our IIIB with the 4 blades. IIRC 100% rpm was 1490 rpm. We ran 100% for takeoff, 98% for climb, and I seem to remember 96% for cruise.

It was quieter inside than half of our jets.

All

Thanks for the comments, it's really helpful as we are delving into this.

As far as the pre-buy goes, A BIG thank you to Erwin Klassen who introduced me to Perimeter Aviation, one of the biggest operators of Merlin/Metro's in Canada, they will be doing the prebuy, and ensure we can go through the import process smoothly. (Importing a plane into Canada is akin to giving birth to a porcelain doll )

I have another question for the group, it's been about 5 years since I flew in a few Mu2's, so my memory might be inaccurate, however it seemed like the LEFT engine start in the video was much too long? (I have also sent this to my mechanic that will obviously go through the engines very carefully).

Thoughts?

[youtube]https://youtu.be/I4p6BtLvENA[/youtube]

Hilgard

Yes that is slow. Should be about 1%/sec minimum

I think most guys run their MU-2 at 100%. They run cooler at 100% than 96%

It is a bit slow, but he is enriching it to around 650 instead of over 700 for the right engine, and that can make a big difference in start time. I suspect the start fuel schedule on the left engine is a bit under what it needs to be.

Does the Merlin allow cross gen starts? The MU2 doesn't. If you have cross gen, then the second engine should be quite a bit faster than the first.

Was this n GPU or battery start? If battery start, are there two batteries, and if so, do you have a parallel series switch? Which position was it in?

In the MU2, after a start, we recharge the batteries to under 100 amps (mine got to 50 amps usually in under a minute) and then started the other engine. What you see here appears to be back to back starts on battery without a recharge, which means the second engine gets less battery to work with. Next time, start them in the other order to see how that changes things.

The 1% per second metric is a guideline. If it is a little under, not terrible. The main thing is control the temperature.

While this is a little slow, the under enrich and back to back battery starts suggest nothing is terribly amiss.

Mike C.

There is no prohibition against operating at 100% RPM, so it isn't "contrary" to do so.

Honeywell advises the engine wear is less at 96% and suggests you use.

Plenty of TPE331 engines run at 100% and make TBO just fine.


If so, MSP is the worst deal ever.

Over a 5000 hour TBO cycle, you will spend about $300K in HSI and OH on a -10 engine. Works out to $60/hour. You math results in almost $1M in program fees per engine per TBO cycle.

Mike C.

Bruce

I went and looked back through what they provided, I quoted wrong. It's actually around $87/hour for each engine.

I don't think they are lying.

Hilgard

Edited for the usual spelling and grammar mistakes.

It was the FBO's GPU.

I think I read somewhere that the Merlin does allow cross gen starts, I will have to look again.

Hilgard

A video of the voltage gauge during start sequence would be helpful to understand how well it was working.

A good GPU will hold the voltage above 20 volts on initial start, preferably 22 volts, with it rising above 24 volts during the start.



In the MU2, there are 3 kinds of starts:

1. Battery parallel: the general start on battery, not so hard on the system.

2. Battery series: a super high power start usually used in the cold. Stresses the electrical system and the batteries quite hard.

3. GPU: starting on external power. The batteries are still in circuit in parallel mode.

There is no cross generator start on the MU2.

GPUs vary a lot in quality and power. Don't use "battery carts", they usually suck and sometimes they end up stealing charge from your airplane. AC line powered or engine driven usually work well.

TPE331 can be hard to start in cold. I find the best way to start in cold is battery series. This is better than GPU, even, due to 48 volts on the starter. Really hard on the batteries, relays, wiring, and starter though.

In contrast, the JT15D-5A on my V start so easily! And it has only one battery.

Mike C.

So, I'm a PT6 and (more recently) JT15 guy and I'm pleading ignorance...

What the heck is the pilot doing with his fingers in this video?! On the PT6 and JT15s we just spin the engine, introduce fuel, then monitor.

He looks like he's starting a big radial engine...

Thanks for the education!
Robert

He is pushing the "enrich" button which introduces more fuel.

TPE331 are hard to start because you spool up everything, it is all geared together. To do that, you really need to start pretty high on the fuel schedule. Due to variations, the controller can't be trusted to do that by itself, so it is set somewhat lower than need and the pilot adds extra fuel to "top it off" and keep the engine starting well.

Some TPE331 don't need much enrich, some need a lot. Basically, it is a manual fuel control used only during start. The button pushing is modulating the amount of fuel being added. After start, it isn't used.

Starting a TPE331 is a dance of eyes watching a bunch of stuff and fingers pushing buttons.

Mike C.

FWIW, my Solitaire has the SRL system which manages it, I never use the enrich buttons. That said they are still there in the event of SRL malfunction or whatever might need a manual option.

My experience was with the long body airplane, and IIRC the system was similar in the short body models.

Cross gen starts were normal when doing a battery start.

The 226's could also select the batteries to Series for a faster start. I can't remember if the 227's could or not at the moment. I'd have to dig out my old .PPT's that I wrote for the ground schools..

My experience was with the long body airplane, and IIRC the system was similar in the short body models.

Cross gen starts were normal when doing a battery start.

The 226's could also select the batteries to Series for a faster start. I can't remember if the 227's could or not at the moment. I'd have to dig out my old .PPT's that I wrote for the ground schools..

Don't know if it will help.
Give a shout to John Atkin in San Antonio. Bison aviation
https://bisonaviation.com/
He bought a Swearingen in Tulsa some years back.