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Thread: POH data/info questions

  1. #1
    Birdseyeview's Avatar
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    Default POH data/info questions

    I found a POH outline in section 8 of the Pilot's Handbook of Aeronautical Knowledge and am following it as close as I can while creating my own POH. In the "Limitations" chapter of the POH I'm writing for my series 6 with a 912ULS I'm trying to figure out a couple of things and wondered if others have already discovered them:

    OIL TEMP:
    On page 10-1 under "General Limits of Operation" in the Rotax Operators manual it states the normal oil temp range is 190-230F, with min and max temp at 120F and 285F, respectively.
    On page 10-5 of this same section of the Operators Manual it states the normal range is 190-230F, with min and max temp at 120F and 266F
    On page 7-1 "Operating Limits" of the Engine's Installation Manual it states the normal oil temp range is 190-250F, with min and max temp at 120F and 266F, respectively.
    On page 2.8 of section 05-50 of the Maintenance Manual it states that "with oil temps in excess of 280F max for 5 min, localize the cause, then below that it states that oil temps in excess of 320F may cause damage.
    I'm assuming that I should go with the 285F max in my POH and I'm assuming that any min temp is not really a limitation worthy of my POH. Are these good assumptions

    CHT:
    On page 10-1 under "General Limits of Operation" in the Rotax Operators manual it states the max CHT is 300F, with no statement about a "normal" range
    On page 10-5 of the same section of the Operators Manual it states that the max CHT is 284F, with no mention of a "normal" range
    On page 7-1 "Operating Limits" of the Engine's Installation Manual it states the max CHT is 275F, with no mention of a "normal" range
    On page 2.7 of section 05-50 of the Maintenance Manual it mentions a couple of maintenance actions required if the CHT exceeds 360F max for short term and longer than 30 minutes exposure.
    I'm assuming that 300F is the only limit I should put in my POH. Is this a good assumption?

    EGT:
    On pages 10-1 or 10-5 under "General Limits of Operation" in the Rotax Operators manual there is no mention of an EGT limit or normal range
    On page 7-1 "Operating Limits" of the Engine's Installation Manual it states the max EGT is 1620F at takeoff, max 1560F (at all other flight speeds?), and "normal" operation at 1470F
    There is no mention of EGT anywhere in the Maintenance Manual that I could find.
    I assume that 1620F max at takeoff speed and 1560F max at all other speeds is what I will put in my POH. Is this a good assumption?

    Service Ceiling:
    I understand the definition of this term but I can't seem to find it defined anywhere for my airplane config. From the little I can find on this topic I'm assuming the ceiling is somewhere above 10,000 ft. Since I'm planning to certify my plane as an LSA and I currently have a sport pilot license that restricts my ceiling to 10,000 ft I'd have to have a licensed Private Pilot discover this for my plane during the flight test, or beyond, if I really need to know what it is. The Pilot's Handbook of Aeronautical Knowledge doesn't list the service ceiling as a required limitation in the POH. As a result, I'm assuming that I can leave it out of my POH all together, or place it in some descriptive section as "info only", if I can discover or calculate it. Is this a good assumption?

    Door Opening Max Speed:
    I couldn't find mention of this in the forum topics and don't plan to have this listed in the "Limitations" section of my POH but do plan to include it in the "Systems Description" section where I describe the doors and their operation. Is there a consensus on this number or do I need to test for it during my flight testing?

    I appreciate any feedback from anyone who has tackled these confusing numbers in the Rotax documentation and how they apply to their POH. You don't need to answer all my questions in order to respond. I'll take it as it comes piece by piece. Thanks
    Larry Olson
    Kitfox Series 6 - 1st Flight Oct 2021
    Tri-gear, smooth cowl
    912 ULS

  2. #2
    Senior Member PapuaPilot's Avatar
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    Default Re: POH data/info questions

    I put 80 MIAS as the max speed with open doors in my POH, but I don't remember where I got the number from. I am certain this is the right number.

    The service ceiling is determined by flight testing. Mine turned out to be 17,000' and I had to take an oxygen bottle on that flight. Here is the definition: The height above sea level at which an aircraft with normal-rated load is unable to climb faster than 100 feet per minute under standard air conditions. If you don't want to or can't do this I would just put "Greater than 10,000' MSL".
    Phil Nelson
    A&P-IA, Maintenance Instructor
    KF 5 Outback, Cont. IO-240
    Flying since 2016

  3. #3
    Senior Member jiott's Avatar
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    Default Re: POH data/info questions

    Larry, the redline values I have for my 912 ULS are:

    Oil Temp 266F
    CHT 275F
    EGT 1616F

    These numbers came from my Rotax Operator's Manual that was current when I purchased my engine in 2012.

    Also I agree with Phil-max door opening speed 80 mph, as taught by Stick & Rudder (don't know where it is written).
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  4. #4
    Birdseyeview's Avatar
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    Default Re: POH data/info questions

    Guys, Thanks for your inputs. I should have noted that my Rotax manuals were all dated from 1998 and back then Rotax didn't seem to have explained very well why so many different temp limits were depicted across their various manuals, or some of the apparent discrepancies may have just been flat out overlooked errors. I'm sure that since then the 912 ULS manuals have been cleaned up and any confusing or apparent discrepancies removed and/or explained better. So I appreciate inputs from more recent manuals.
    Larry Olson
    Kitfox Series 6 - 1st Flight Oct 2021
    Tri-gear, smooth cowl
    912 ULS

  5. #5

    Join Date
    Oct 2018
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    Kitchener, Ontario
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    Default Re: POH data/info questions

    Nope Rotax manuals still crap

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