TSIO-520-K vs TSIO-520-N

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    I just purchased a 1974 414 with the K model engines. My POH (Handbook) goes into detail about the N model engines. I have the owner’s manual for all Continental 520 engines and all I see is a difference in HP of the two models. Does anyone know of any other differences?
    I’m in need of an overhaul for both engines, as I am going to put this aircraft on a single-pilot operated 135 cert. Should I wait for the overhaul due to the possible upcoming AD?


    From Type Certificate Data Sheet E8CE:

    “The Model TSIO-520-K is similar to the TSIO-520-J except for reduced rating, deletion of induction air intercooler and calibration for a single point waste gate controller.”

    “The Model TSIO-520-N is similar to the TSIO-520-J except for revised rating.”

    So it would say the main difference is the wastegate setup, rating, and possession (or lack) of an intercooler.


    As far as the overhauls go, if anything there may be a shortage of cylinders once the NPRM is turned into an AD (assuming it is). Many engines at that point will become unairworthy. Since the NPRM doesn’t impact currently produced cylinders, now might not be a bad time.

    Good luck on the 135 cert. We considered it a few times, but between having timed out engines (now overhauled), yeared out props (with no intentions of overhauling), an AP that can’t capture and follow a glide slope, and what I figured would amount to a whole host of other issues, it just never made sense to try. I was involved with getting a supposedly “135-ready” Navajo on a 135 cert. $50,000 later, it was on. And that didn’t even include anything fun like new avionics, engine overhauls, or an autopilot that wasn’t suicidal!


      I would be surprised if there are any TSIO-520K engines still in the system. They were 285 HP which was very inadequate for 340s or 414s. The TSIO-520N have very few if any still in the system. Most if not all have been replaced by the TSIO-520NB which has the 7th stud added to the case in between cylinders 1 and 3, and 3 and 5, and 2 and 4, and 4 and 6 and has a beefed up case.


      Thanks for all the info, guys.
      I do have the ‘NB’s’ there was a massive disconnect between the logs and the manual, and what’s on there already.

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