PT-6: Prop feathered or not?

ZeroPapaGolf

ZeroPapaGolf

Well-Known Member
What determines if the prop on a PT-6 feathers on shutdown or not? I saw a King Air 200 not feather on shutdown a few months back, and assumed they had left the prop levers forward. But today I was looking at a Meridian for sale, and one of the photos showed the prop not feathered at shutdown. That aircraft doesn't have a prop lever. So, what's the deal there? Here's the Meridian: (the fourth image is the unfeathered shutdown) http://www.controller.com/listingsd...IPER-MERIDIAN/2006-PIPER-MERIDIAN/1269295.htm
 
I don't have an answer, but just looking at the pictures, it looks like there are a couple of pictures of the prop feathered after shutdown. So, I bet that the one picture was taken with a high enough shutter speed that the prop only appears stopped.
 
On the TBM, you can shut down with the prop lever forward (not recommended by SimCom, our maintenance guy says otherwise, whatever...), which means it takes forever for the prop to stop, and when it does the blades will be pretty flat. They will move to a feathered position within a minute or two however.

That picture may have been taken just after such a shutdown, as it looks like someone's in the plane.

As far as I know, all props connected to PT-6's will move to a feathered position on shutdown, but I could be wrong.
 
It makes no difference either way, but it's not possible for a pt6 to stay flat when off. It's oil pressure that keeps it from feathering and there's no lock like a garrett or piston.
 
With the Meridian photo, the engine is definitely running. You can see some very faint motion blur around the prop tips. High shutter speed.

I worked around PT6's for almost 4 years and never saw one that didn't feather on shut down. When the prop levers are left full forward on shutdown, it just takes longer for the prop to wind down. It does feather though by the time it stops moving.

The only planes I've seen PT6's not feather on shutdown is Twin Otters on floats. They have start locks and keep them engaged to minimize water splatter (in salty environments) on the plane during start up.
 
[quote="N519AT, post: 2074999, member: 1490"

The only planes I've seen PT6's not feather on shutdown is Twin Otters on floats. They have start locks and keep them engaged to minimize water splatter (in salty environments) on the plane during start up.[/quote]

The caravan float plane comes with the locks as well, but its to give you instant forward motion on starting up when on the water. On the van with out the locks its pretty sketchy to do any non dock work as the airplane starts a left 360 from the power of the exhaust before the prop can make it out of feather.
 
Thanks guys, that is very interesting. I guess when I saw the King Air with props not feathered, it was soon enough after shutdown that they might not have feathered yet if prop levers were forward (I watched it shut down but didn't really keep watching after the props stopped turning)
 
Yeah, by default when the oil pressure depletes on a PT-6 the prop feathers. If it doesn't then something is wrong.
 
You can shut down a Meridian down without feathering the prop. I done it myself. Just pull the emergency fuel cutoff.
 
jknight8907 said:
Thanks guys, that is very interesting. I guess when I saw the King Air with props not feathered...
Click to expand...

You sure it wasn't 331 powered? Not sure about the 200, but I know where are a few out there with the Garrett conversion.


KingAirB100_exterior_e.jpg
 
My company has Turbine Otters and Beavers on floats, which all have PT-6s with prop locks for the docking issues. The interesting thing to note is that the company prefers the prop to be feathered when approaching the dock and upon startup. This supposedly reduces noise... not sure I agree. The dehavilland airplanes have dual exhaust stacks though, so they don't have too many directional control issues when leaving a dock feathered, the only problem is the lack of quick forward movement if there is any wind or obstacles...
 
TwoTwoLeft said:
You sure it wasn't 331 powered? Not sure about the 200, but I know where are a few out there with the Garrett conversion.


KingAirB100_exterior_e.jpg
Click to expand...
Could be. I'm 99% sure it was a PT6, though, as I distinctly remember doing a double-take on the props, and noticing it did indeed have PT-6 style exhaust.
 
Jimmy_Norton said:
That's not a conversion, that's a B100 and it came from the factory like that.
Click to expand...

Good story behind that. Apparently the Pratt factory went on strike, so Beech started putting 331s in their 100s. Went faster, climbed better, on less gas, so naturally, when Pratt started making engines again, they told them to go...sell them some more PT-6s! *puzzle*
 
Yup, PT6 will always feather on shut down by design. It can handle starting and idling in feather easily so there was no low pitch latch mechanism built into the prop hub assembly.

That's interesting about the PT6s on floats though. Any idea if that latch mechanism was similar to the Hartzell as found on the TPE331?
 
Boris Badenov said:
Yeah, PT-6s just naturally assume that they're broken. Unlike the Manly 331...
Click to expand...
You mean to tell me you've never once forgot to put it on the locks on shutdown, or at the least maybe thought you buried it in reverse but it wasn't quite enough?
 
z987k said:
You mean to tell me you've never once forgot to put it on the locks on shutdown, or at the least maybe thought you buried it in reverse but it wasn't quite enough?
Click to expand...

No sir, I was TRAINED PROPERLY. Ok, maybe once when I'd tried to start the thing without a powercart at like -10C, but that doesn't count. Because I say it doesn't. And lord didn't I have a fun time trying to figure out how to get it back on the locks, thumbing through the manual with thumbs I couldn't feel. I mean, theoretically.
 
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