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accident in Knoxville, IA

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  • accident in Knoxville, IA

    https://app.ntsb.gov/pdfgenerator/Re...Final&IType=LA
    http://www.kcci.com/article/emergenc...reated/9519613

    I am a bit surprised at their trying to get 135hp by adding a turbo to the Rotax 912 ULS. Sounds like this one definitely had a turbo-related issue.

  • #2
    Hmph. Hot-rodding a 1200 cc engine to make 135 hp? Really?

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    • #3
      Please understand I wasn't there and am not being critical of the pilots decisions.

      I often spend time with students trying to learn from others misfortune and reinforce my somewhat extensive safety precautions.

      I feel it is best to only fly passengers with a properly running gyroplane.
      The continuing challenges with the engine would have restricted me to flying the pattern solo until I had the issues resolved.

      Part of becoming familiar with an airport is to look for emergency landing spots and identify obstructions (wires in this case).

      At 500 feet agl I can glide 1,500 feet to find a suitable emergency landing zone. The runway at OXV is 75 feet wide and 4,000 feet long. There are lots of open fields at the departure end of runway 15.
      https://www.google.com/maps/@41.2984.../data=!3m1!1e3

      I assume the engine is going to go quiet on every takeoff and prepare for that.

      I do not need to check the altimeter to see that I am descending.

      Part of the takeoff procedure is to make note of the rate of climb with the vertical speed indicator.

      I suspect earlier recognition of the problem would have allowed them to return to the airport.

      I feel flying closed traffic the pattern should always be within gliding distance of the runway.

      Before I leave the runway environment I check that the temperatures and pressures are in the green.

      I suspect the engine tachometer and manifold pressure gage provided information that the engine was not at takeoff power long before they left the runway environment.

      I wasn't there so I don't know what other challenges existed.

      These are just some thoughts to perhaps make your takeoff procedures safer.
      Last edited by Vance; 04-20-2018, 07:55 AM.
      Regards, Vance Breese Gyroplane CFI http://www.breeseaircraft.com/

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      • #4
        was this last year? NTSB report is dated 2017?
        Don Randle
        Gyroplane CFI

        "Flying a Gyro is the most fun you can have with your clothes on!"

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        • #5
          Yes it was last year Don Randle.

          The factual report was recently issued.
          Regards, Vance Breese Gyroplane CFI http://www.breeseaircraft.com/

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          • #6
            When turbocharging an engine you can gain 7% in HP for every 1 lb of boost,a intercooler is not needed with only 5-6 lbs of boost,

            The more pressure that's put on the engine the less reliable it becomes,there is a breaking point for reilabllity Vs HP gain.

            A little 1200 cc engine will have smaller/weaker parts,ie the crankshaft.rods ,pistons and valve train.I would think that much HP is

            taking it to its limits.

            Also turbocharging an engine with carbs is a really bad idea to me.The carbs would have to be designed to work with external

            air pressure applied to them as opposed to pulling a vacuum to operate them properly.
            Best Regards,
            Eddie Sigman,Polvadera,nm
            (575) 835-4921

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            • #7
              The 912 ULS is a 1352 cc engine. The 914 is 1211 cc, basically, a turbo'd 912 UL. All three use the same pressed crank which seems to be a weak link, especially for those with upped power. Not a huge point here, just clarification.

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              • #8
                Originally posted by magknight View Post
                The 912 ULS is a 1352 cc engine. The 914 is 1211 cc, basically, a turbo'd 912 UL. All three use the same pressed crank which seems to be a weak link, especially for those with upped power. Not a huge point here, just clarification.
                A point of note is that Rotax pushes that crankshaft only to 115hp in the 914. Not to the 135 hp that Xenon pushes it to.
                When they decided to go to make the 915 at 135hp, they redesigned the whole thing and went to fuel injection to eliminate the Carbs running on turbo boost issue.

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                • #9
                  Up to 125 HP the crank should be able to handle with reserve for safety a bit. 135 HP IMO requires welding and rebalancing the crank.
                  915iS is not ready for fixed pitch prop or ground adjustable prop. The whole mapping in the ECU is done for a constant speed prop. There is a single lever operation constant speed prop being developed by MT prop from Germany using a Searey Technology Demobstrator here and I have had extensive hours long conversation with the engineer helping do it.
                  Min about 6 months time Rotax plans to have an ECU mapping appropriate for a ground adjustable or fixed pitch prop done. Instead of getting 141 full HP,we may see only 135 hp out of it

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                  • #10
                    Thanks for the update Fara.
                    Best Regards,
                    Eddie Sigman,Polvadera,nm
                    (575) 835-4921

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