Turboprop info....

Heavy Haulin

Heavy Haulin

Well-Known Member
I'm looking to get myself up to speed on turboprop systems and op's, right now the Garretts in particular. Anybody know of some good reading material on the TPE331 & PW PT6? So far, I have not been able to locate much on the internet.

Thanks for your time,
 
gotWXdagain

gotWXdagain

Polished Member
Garretts: Make much noise, drain batteries quickly.

Pratts: Push power lever forward, eat sandwich, observe torque needle begin to rise. Also you can shoot one with a medium-caliber bullet and the typical response is “Thank you sir, may I have another?”
 
Roger Roger

Roger Roger

Paid to sleep, fly for fun
gotWXdagain said:
Garretts: Make much noise, drain batteries quickly.

Pratts: Push power lever forward, eat sandwich, observe torque needle begin to rise. Also you can shoot one with a medium-caliber bullet and the typical response is “Thank you sir, may I have another?”
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Unless, you know, the bullet comes close to a py line. The garret you can pretty much smash the fuel control with a sledgehammer and the troubleshooting charts lists the symptom as “slow, cool starts”.
 
z987k

z987k

Well-Known Member
Roger Roger said:
Unless, you know, the bullet comes close to a py line. The garret you can pretty much smash the fuel control with a sledgehammer and the troubleshooting charts lists the symptom as “slow, cool starts”.
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Or that bullet gets anywhere near the fragile first compressor stage of the pratt.
While the Garret eats FOD for breakfast lunch and dinner for 8 years straight.
Oh and heaven forbid the pt6 is parked within 100 miles of an ocean. 1st stage compressor corrosion city!
 
milleR

milleR

Well-Known Member
z987k said:
Or that bullet gets anywhere near the fragile first compressor stage of the pratt.
While the Garret eats FOD for breakfast lunch and dinner for 8 years straight.
Click to expand...
I remember my first Garrett bird ingestion ... smelled funny for a sec and that was the end of it. Meanwhile my old boss was freaking out about the ice vanes on his 90 every time you looked at a sub zero cloud funny.
 
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z987k

z987k

Well-Known Member
milleR said:
I remember my first bird ingestion ... smelled funny for a sec and that was the end of it. Meanwhile my old boss was freaking out about the ice vanes on his 90 every time you looked at a sub zero cloud funny.
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I forgot about the ice vanes. Honestly, I think they even erode over time just due to clean air ingestion. I mean the engine works, it's just the other option works better after they started using the helical cut gear circa 1990something with the AD in 02 I think.
 
milleR

milleR

Well-Known Member
z987k said:
I forgot about the ice vanes. Honestly, I think they even erode over time just due to clean air ingestion. I mean the engine works, it's just the other option works better after they started using the helical cut gear circa 1990something with the AD in 02 I think.
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Pratt makes one helluva motor .... Garrett AiResearch just made a better one.

I loved flying KA’s and I loved the PC-12 but I’m dreading the day I have to go back to a PT-6.
 
Roger Roger

Roger Roger

Paid to sleep, fly for fun
z987k said:
Or that bullet gets anywhere near the fragile first compressor stage of the pratt.
While the Garret eats FOD for breakfast lunch and dinner for 8 years straight.
Oh and heaven forbid the pt6 is parked within 100 miles of an ocean. 1st stage compressor corrosion city!
Click to expand...
Ha. We had our one Caravan PT6 go out for a FOD repair this spring. No idea what caused it but something snuck through the screen and made us replace 2 blades.

milleR said:
I remember my first Garrett bird ingestion ... smelled funny for a sec and that was the end of it. Meanwhile my old boss was freaking out about the ice vanes on his 90 every time you looked at a sub zero cloud funny.
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Haha. Though the operation down the way has had to remove 1 or 2 331s over the years from Otters due to bird ingestion. I forget if the teardowns actually found any damage or not though.
z987k said:
I forgot about the ice vanes. Honestly, I think they even erode over time just due to clean air ingestion. I mean the engine works, it's just the other option works better after they started using the helical cut gear circa 1990something with the AD in 02 I think.
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The durability of the ice vanes is entirely airframe manufacturer dependent as those are an airframe item. Caravan ones are the ones I’m familiar with and they’re “ok”...have a couple strong points and a couple really “wtf?” weak points.
 
milleR

milleR

Well-Known Member
Roger Roger said:
Ha. We had our one Caravan PT6 go out for a FOD repair this spring. No idea what caused it but something snuck through the screen and made us replace 2 blades.


Haha. Though the operation down the way has had to remove 1 or 2 331s over the years from Otters due to bird ingestion. I forget if the teardowns actually found any damage or not though.

The durability of the ice vanes is entirely airframe manufacturer dependent as those are an airframe item. Caravan ones are the ones I’m familiar with and they’re “ok”...have a couple strong points and a couple really “wtf?” weak points.
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I always thought "ice vanes" implied weakness ... "inertial separator" implied badass off-road capability. Semantics, but still ... throw a rock in there and see what happens. A Garrett just spits out gravel and wonders why you couldn't find a bigger rock :D
 
Roger Roger

Roger Roger

Paid to sleep, fly for fun
milleR said:
I always thought "ice vanes" implied weakness ... "inertial separator" implied badass off-road capability. Semantics, but still ... throw a rock in there and see what happens. A Garrett just spits out gravel and wonders why you couldn't find a bigger rock :D
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Also just for fun my successor has pictures of what happens to a 331 that gets started with the inlet plug in.
 
J

JeppUpdater

Well-Known Member
Garrett: will munch through birds, ice, and pretty much anything else in its way, provided you have a nuclear power plant to start it the first start of the day. It angers every ramper at the airport and makes you more manly through a combination of required smoking, drinking, and building up new leg muscles from using left rudder.

Pratt: if a pebble slips in the intake the engine will explode in a fashion similar to a frag grenade. It is mounted backward in the airplane which should tell you a lot about Pratt’s great ideas. But it has the advantage that you can tie the prop to the nose gear so it won’t spin and then run the engine as an APU to heat up the cabin.



(Seriously: I’ve got a ton of hours in both and do prefer the Garrett for it’s responsiveness and efficiency. I like Pratt’s for their independence from ground equipment and ability to feather them in flight for training and on ground to test the ability before flight.)

I’ve got pilot guides for both engines if anyone needs a copy.
 
gotWXdagain

gotWXdagain

Polished Member
The backwards mounting/triple 5x flow reversals, and free turbine is, I suspect, one of the chief reasons why the PT6 is still being used while the Garretts seem to be going the way of the ...wait for it... Metroliners.
 
Roger Roger

Roger Roger

Paid to sleep, fly for fun
gotWXdagain said:
The backwards mounting/triple 5x flow reversals, and free turbine is, I suspect, one of the chief reasons why the PT6 is still being used while the Garretts seem to be going the way of the ...wait for it... Metroliners.
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It has more to do with Honeywell giving exactly zero effs about marketing their engine to OEMs.
 
Roger Roger

Roger Roger

Paid to sleep, fly for fun
gotWXdagain said:
Even manufacturers get shiny jet syndrome.


Sent from my iPad using Tapatalk Pro
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I guess I wasn’t 100% correct...they’re more than happy to market them to the military for drones. When I went to the Honeywell mx class a couple years ago we weren’t allowed to tour the 331 assembly line because it was mostly motors for Reapers.
 
Cessnaflyer

Cessnaflyer

Wooooooooooooooooooooooooooooooo
Are PT6's really that fragile? We've done some beating on our -61's and the mechanic says they seem to be holding up fine.
 
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