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"Devices" Near PT6A Exhaust Stacks

Tue Jul 24, 2012 12:17 pm


I noticed on a King Air 350 recently, that around both exhaust stacks on both engines, had some sort of "devices." These appear to be some kind of aftermarket retrofit, consisting of "strakes"...I assume some kind of vortex generators. I've never seen this on any other PT6A powered aircraft. What are the purpose of these exhaust devices? Some kind of performance enhancement?

I was able to trace the tail number and found some pictures of the aircraft online. I cropped out the right side engine to show these devices here:

Strange devices on PT6A exhaust stacks


[Edited 2012-07-24 05:20:49]
T prop
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Joined: Tue Apr 03, 2001 4:33 pm

RE: "Devices" Near PT6A Exhaust Stacks

Tue Jul 24, 2012 4:50 pm

I've installed those on a King Air, they're part of a kit from Raisbeck Engineering. If I remember, the ones in the picture besides helping with low speed performance, also keep exhaust soot from blackening the rear part of the nacelle.
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RE: "Devices" Near PT6A Exhaust Stacks

Tue Jul 24, 2012 4:53 pm

I think they are Raisbeck composite exhaust stack fairings .

Here's a description from the website:
"Small composite fairings over fronts of exhaust stacks on all P&WC PT6A-powered Beechcraft King Air and Super King Air models; prevent power loss from hot air entering forward cowling and engine inlet and reduce drag by streamlining propeller wake; fairing held in place by camlocks; two 'delta-wing' vortex generators on fairings divert high-energy gases between exhaust and cowling, keeping exhaust soot from accumulating on nacelle and wing."

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