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For a given turboprop plane such as the ATR-72, there doesn't seem to be a pylon as on turbofan driven planes. This question: How are engines mounted onto wings? has answers that detail how a pylon is attached to the engine, but not how the pylon is attached to the wing itself.

What I want to know is how in the case of the ATR-72 or similar, are the turboprop engines, or pylons for turbofans are attached to the wing itself. Are they attached to a special type of rib? Are they attached to the spar(s)? Or both, or an entirely different structure designed for this purpose? How do they avoid concentrating the load?

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As usual an image is worth more than a thousand words (cutaway source):

enter image description here

As visible, the engine is mounted enclosed inside a truss structure (composed for example by the beams 191 and 199) interspersed by one frame (192) and one rear bulkhead (189). This whole structure is then attached to the front and rear spar at the same location where there's also a rib.

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  • $\begingroup$ Ah, thanks, this really helps visualise it! From my limited understanding, it seems to be attached to the intersection of that front spar and mid-engine rib near the top and bottom, which in themselves are not special? $\endgroup$
    – keg504
    Aug 30, 2023 at 19:56
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    $\begingroup$ The design of the ribs doesn't seem to be specific but almost certainly the spar there is reinforced/thicker. But that really depends on the engineering choices made by the manufacturer: for example the rib design of the C295 is different from the other ribs for that location (number 62 in the linked cutaway). $\endgroup$
    – sophit
    Aug 30, 2023 at 21:13
  • $\begingroup$ Thanks, I understand now. By the way, where are you getting these cutaway images from? They are really helpful in understanding! $\endgroup$
    – keg504
    Aug 31, 2023 at 6:19
  • $\begingroup$ @keg504: any search engine is good, just look for the aircraft's name and the keyword "cutaway" $\endgroup$
    – sophit
    Aug 31, 2023 at 20:05
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A turboprop isn't really different from the answers given in the question you link to.

There is typically a frame of tubes that hold the engine and take the loads back to the wing. The frame will connect to both the front and rear spar.

Where a frame connects to the spar, there will be some fitting to act as a hardpoint for the connection. Often, the ribs in this area will have either closer spacing or will be beefed up in some way.

Even when there is a pylon, there will be a frame through the pylon up to the wing, the skins of the pylon are mostly a fairing.

Here is a nice cutaway of the ATR-72 (these may not be perfectly accurate), but it gives some idea.

https://conceptbunny.com/wp-content/uploads/2018/07/ATR_72.gif

Here is a photo of a nacelle with the cowl panels removed.

https://cdn.jetphotos.com/full/5/64776_1583446914.jpg

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