The TBM 940 and Cessna caravan both have the PT6A turbo prop engine. The sister caravan has one single exhaust stack under the engine cowling, and almost all other small turbo props have dual exhaust on both sides of the engine cowling. Is there a reason for this and is one better than the other?

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  • $\begingroup$ Your picture of the Caravan does not have a PT6A. Aftermarket companies convert them to the TPE331 which has a rear exhaust outlet, thus the location of the exhaust pipe. If you had references for your pictures this would be easy to verify. see for example $\endgroup$
    – Pilothead
    May 8, 2023 at 2:35
  • $\begingroup$ Sorry about that, I was just trying to show how the caravan has the exhaust under the cowling regardless of the engine. $\endgroup$
    – Boeing787
    May 8, 2023 at 2:56
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    $\begingroup$ The C208 photo DOES have a PT6A. The exhaust exits much closer to the front than the TPE331 exhaust. Also, your reply does not answer the question. The reference for the C208 photo is commons.wikimedia.org/wiki/… FedEx does not operate TPE331 C208. $\endgroup$ May 8, 2023 at 5:46
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    $\begingroup$ Please include image sources where possible. $\endgroup$
    – Jamiec
    May 9, 2023 at 11:15

1 Answer 1


This depends on whether the engine has its exhaust outlet in the front of the engine or the back, and whether the fuselage is pressurized or has cabin air inlet vents. You'll put the exhaust beneath the fuselage to keep it from blowing fumes into the cabin air inlets unless the fuse is pressurized, in which case the cabin air is bled off the compressor and exhaust contamination can't occur.


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