Yes engines are relatively easy to overhaul. Fuel controls? They will be going to a CRS.

Looks like they had streaking fuel nozzles based on the patterns in the return duct. That can lead to damage to wheels and stators.

There are 10 nozzles and you can see that in the 10 patterns, but some are clearly more carbonized than the others indicating something isn't uniform.

In the pictures, I see the 3 stators and the 2nd and 3rd wheels, the first wheel is not pictured. Might be toast. The first stator doesn't look all that great, either.

In a TPE331, keeping your fuel nozzles clean is a key to long engine life. The post shutdown prop spin is part of that effort since it blows away unburned fuel that would otherwise carbonize on the hot nozzles.

Mike C.

The post flight also keeps the wheels from freezing to the shroud and locking up the turbine
We called it "the MU-2 Exercise Plan"

Looks like they had streaking fuel nozzles based on the patterns in the return duct. That can lead to damage to wheels and stators.

There are 10 nozzles and you can see that in the 10 patterns, but some are clearly more carbonized than the others indicating something isn't uniform.

In the pictures, I see the 3 stators and the 2nd and 3rd wheels, the first wheel is not pictured. Might be toast. The first stator doesn't look all that great, either.

In a TPE331, keeping your fuel nozzles clean is a key to long engine life. The post shutdown prop spin is part of that effort since it blows away unburned fuel that would otherwise carbonize on the hot nozzles.

Mike C.

Looks like they had streaking fuel nozzles based on the patterns in the return duct. That can lead to damage to wheels and stators.

There are 10 nozzles and you can see that in the 10 patterns, but some are clearly more carbonized than the others indicating something isn't uniform.

In the pictures, I see the 3 stators and the 2nd and 3rd wheels, the first wheel is not pictured. Might be toast. The first stator doesn't look all that great, either.

In a TPE331, keeping your fuel nozzles clean is a key to long engine life. The post shutdown prop spin is part of that effort since it blows away unburned fuel that would otherwise carbonize on the hot nozzles.

Mike C.

Yes, the very early 500 dumped the fuel on the ground also! I’ve only seen one in my life do that actually, I think it was serial number 39.

Mostly.

The MU2 had the same kit. It accounts for the brief spike up in power as you shut down.

However, the EPA kit doesn't get ALL the fuel away from the nozzle. At some point the flame goes out with a lean mixture, but that's not zero fuel. So a little bit remains. If you spin the prop after shutdown, you help disperse this bit of fuel, plus help cool the turbine down a bit more.

As for shaft bow (the tendency to lock up after shutdown), my engines really never did that, but the idea is to move it every few minutes about one blade width. This turned the high speed rotating group over about 180 degrees. Shaft bow as due to the upper part of the assembly getting hotter than the lower. It really isn't an issue if you do the prop spin and if you park into the wind.


That was the old way, new ay is better for the engine and the environment.

My JT15D-5A engines on the jet don't have a similar system that I am aware of, no evident spike up when shutting down, and there is no way I can rotate either N1 or N2 in the engine. So I presume the Pratt fuel nozzles just stay cleaner for whatever reason.

Mike C.

Mike I have all the official paper PWC JT15D-5A/SBs MMs if you ever need to borrow them. My Library is now 30 feet long. I don't mess with the -5 very often.

Mike

Let's make that happen. Let me know how we do this.

I would want to convert this all to digital somehow so you don't need a fork lift to move it.

Mike C.

I think the TPE331 is still the one turbine that hasn't gone through the roof in overhaul costs. Maybe the Allison C20/C30 as well. Seems like everything else has gone ballistic, from what I hear.

0039 was cut up by White Industries. But I know for a fact 0041 marks it’s territory at shutdown.

Let's make that happen. Let me know how we do this.

I would want to convert this all to digital somehow so you don't need a fork lift to move it.

Mike C.

The early Lear 23s dumped the cutoff fuel until the EPA mandated catch cans
IIRC the early 707s with the straight turbojets (C6) dumped also until catch cans were installed.
I know of an MU-2N (not -10s) that had the over temp controllers removed and they had to be very careful with temps on takeoff.

Looks like they had streaking fuel nozzles based on the patterns in the return duct. That can lead to damage to wheels and stators.

There are 10 nozzles and you can see that in the 10 patterns, but some are clearly more carbonized than the others indicating something isn't uniform.

In the pictures, I see the 3 stators and the 2nd and 3rd wheels, the first wheel is not pictured. Might be toast. The first stator doesn't look all that great, either.

In a TPE331, keeping your fuel nozzles clean is a key to long engine life. The post shutdown prop spin is part of that effort since it blows away unburned fuel that would otherwise carbonize on the hot nozzles.

Mike C.

That appears to be a large exit duct which is actually two layers of metal with an air layer in between. The way I've seen them inspect that is to feel for waviness. If it is super wavy it gets rejected. This is one of the parts that gets sent out, welded and recoated.