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Thread: Sundowner full throttle RPM

  1. #1

    Sundowner full throttle RPM

    Hi guys and gals, here's today's question....

    I have a newly acquired 1978 Sundowner with a Lycoming O 360 A4K 180 HP
    engine
    turning a Sensenich 76EM8S5 0 60 prop.

    Engine has 4400 hours, 100 hours since overhaul.

    A) POH says takeoff power and maximum continuous power is
    full throttle at 2700 RPM.

    On take-off and climb with full throttle the tach only shows 2350-2400.
    Straight and level full throttle tach only shows 2500.

    Temperature was 58 degrees F.
    Estimated weight at takeoff (just me and 40 gal fuel) 2050lbs.

    Are these tach readings cause for concern?

    Thanks.

    Steve
    N2009D

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  2. #2

    Sundowner full throttle RPM

    Yes but, could be nothing more than a worn out tach reading wrong.

    jon

    In a message dated 28/11/2005 7:07:59 PM Eastern Standard Time,
    MrLucky353@aol.com writes:

    Hi guys and gals, here's today's question....

    I have a newly acquired 1978 Sundowner with a Lycoming O 360 A4K 180 HP
    engine
    turning a Sensenich 76EM8S5 0 60 prop.

    Engine has 4400 hours, 100 hours since overhaul.

    A) POH says takeoff power and maximum continuous power is
    full throttle at 2700 RPM.

    On take-off and climb with full throttle the tach only shows 2350-2400.
    Straight and level full throttle tach only shows 2500.

    Temperature was 58 degrees F.
    Estimated weight at takeoff (just me and 40 gal fuel) 2050lbs.

    Are these tach readings cause for concern?

    Thanks.

    Steve
    N2009D




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    BAC-Mail mailing list
    BAC-Mail@beechaeroclub.org
    http://www.beechaeroclub.org/mailman/listinfo/bac-mail

  3. #3

    Sundowner full throttle RPM

    Steve, sounds about fifty rpm below my 78 sundowner with 1200 hours on the engine. You can check the accuracy with a hand held tach. Mac tools about $100. Richard

    -----Original Message-----
    From: MrLucky353@aol.com
    Sent: 11/28/05 6:07:33 PM
    To: "bac-mail@beechaeroclub.org" <bac-mail@beechaeroclub.org>
    Subject: [BAC-Mail] Sundowner full throttle RPM


    Hi guys and gals, here's today's question....

    I have a newly acquired 1978 Sundowner with a Lycoming O 360 A4K 180 HP
    engine
    turning a Sensenich 76EM8S5 0 60 prop.

    Engine has 4400 hours, 100 hours since overhaul.

    A) POH says takeoff power and maximum continuous power is
    full throttle at 2700 RPM.

    On take-off and climb with full throttle the tach only shows 2350-2400.
    Straight and level full throttle tach only shows 2500.

    Temperature was 58 degrees F.
    Estimated weight at takeoff (just me and 40 gal fuel) 2050lbs.

    Are these tach readings cause for concern?

    Thanks.

    Steve
    N2009D

    _______________________________________________
    BAC-Mail mailing list
    BAC-Mail@beechaeroclub.org
    http://www.beechaeroclub.org/mailman/listinfo/bac-mail

    _______________________________________________
    BAC-Mail mailing list
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  4. #4

    Sundowner full throttle RPM

    I'd think that engine should be able to achieve 2700 rpm once leveled out at
    some point?

    Dunno why the POH would use that number for take off power. Suppose if the
    bird has a climb prop (if even available for the 'downer), she might do 2700
    rpm on take off..otherwise, no way it'll spin anywhere near 2700 with a
    cruise prop.

    I'm assuming the Sensenich 76EM8S5 0 60 is a cruise prop. Interesting that
    the pich (60) is the same for the 63 Lyc model, that has 20 less horsepower.

    How does the POH wording encompass 2 different props on models that have
    prop options?

    Perhaps full rpms are not achievable with a cruise prop? Any case, old tachs
    are known to be innacurate.

    jon

    In a message dated 29/11/2005 8:06:09 AM Eastern Standard Time,
    rgrimes@realtysouth.com writes:

    Steve, sounds about fifty rpm below my 78 sundowner with 1200 hours on the
    engine. You can check the accuracy with a hand held tach. Mac tools about
    $100. Richard

    -----Original Message-----
    From: MrLucky353@aol.com
    Sent: 11/28/05 6:07:33 PM
    To: "bac-mail@beechaeroclub.org" <bac-mail@beechaeroclub.org>
    Subject: [BAC-Mail] Sundowner full throttle RPM


    Hi guys and gals, here's today's question....

    I have a newly acquired 1978 Sundowner with a Lycoming O 360 A4K 180 HP
    engine
    turning a Sensenich 76EM8S5 0 60 prop.

    Engine has 4400 hours, 100 hours since overhaul.

    A) POH says takeoff power and maximum continuous power is
    full throttle at 2700 RPM.

    On take-off and climb with full throttle the tach only shows 2350-2400.
    Straight and level full throttle tach only shows 2500.

    Temperature was 58 degrees F.
    Estimated weight at takeoff (just me and 40 gal fuel) 2050lbs.

    Are these tach readings cause for concern?

    Thanks.

    Steve
    N2009D




    _______________________________________________
    BAC-Mail mailing list
    BAC-Mail@beechaeroclub.org
    http://www.beechaeroclub.org/mailman/listinfo/bac-mail

  5. #5

    Sundowner full throttle RPM

    I own a 75 Sundowner with the same engine.
    Take off is usually 2350 -2400 RPM and straight and level full throttle is
    2650 -2700 rpm.
    I have found that trim in flight makes a big difference, if you are trimmed
    nose high she will fly at a lower rpm than if trimmed straight and level.
    I flew Sunday and had 2500 rpm at altitude until I trimmed for flight and
    then she came right up to 2700 rpm.
    The only other thing I have noticed is when the oil temp is low she stays at
    a lower rpm until she's warmed up.
    Good Luck
    Brian

    ----- Original Message -----
    From: <MrLucky353@aol.com>
    To: <bac-mail@beechaeroclub.org>
    Sent: Monday, November 28, 2005 7:07 PM
    Subject: [BAC-Mail] Sundowner full throttle RPM


    > Hi guys and gals, here's today's question....
    >
    > I have a newly acquired 1978 Sundowner with a Lycoming O 360 A4K 180 HP
    > engine
    > turning a Sensenich 76EM8S5 0 60 prop.
    >
    > Engine has 4400 hours, 100 hours since overhaul.
    >
    > A) POH says takeoff power and maximum continuous power is
    > full throttle at 2700 RPM.
    >
    > On take-off and climb with full throttle the tach only shows 2350-2400.
    > Straight and level full throttle tach only shows 2500.
    >
    > Temperature was 58 degrees F.
    > Estimated weight at takeoff (just me and 40 gal fuel) 2050lbs.
    >
    > Are these tach readings cause for concern?
    >
    > Thanks.
    >
    > Steve
    > N2009D
    >
    > _______________________________________________
    > BAC-Mail mailing list
    > BAC-Mail@beechaeroclub.org
    > http://www.beechaeroclub.org/mailman/listinfo/bac-mail
    >

    _______________________________________________
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    BAC-Mail@beechaeroclub.org
    http://www.beechaeroclub.org/mailman/listinfo/bac-mail

  6. #6

    Sundowner full throttle RPM

    Wonder if a tach can fail in a way that it is accurate at ~ 2400 but be off
    a coupla hundred rpms at max power, leveled in cruise & then read incorrectly?

    Both birds have the same take off rpms..

    jon

    In a message dated 29/11/2005 10:06:28 AM Eastern Standard Time,
    bfoote@e-mart.tv writes:

    I own a 75 Sundowner with the same engine.
    Take off is usually 2350 -2400 RPM and straight and level full throttle is
    2650 -2700 rpm.
    I have found that trim in flight makes a big difference, if you are trimmed
    nose high she will fly at a lower rpm than if trimmed straight and level.
    I flew Sunday and had 2500 rpm at altitude until I trimmed for flight and
    then she came right up to 2700 rpm.
    The only other thing I have noticed is when the oil temp is low she stays at
    a lower rpm until she's warmed up.
    Good Luck
    Brian

    ----- Original Message -----
    From: <MrLucky353@aol.com>
    To: <bac-mail@beechaeroclub.org>
    Sent: Monday, November 28, 2005 7:07 PM
    Subject: [BAC-Mail] Sundowner full throttle RPM


    > Hi guys and gals, here's today's question....
    >
    > I have a newly acquired 1978 Sundowner with a Lycoming O 360 A4K 180 HP
    > engine
    > turning a Sensenich 76EM8S5 0 60 prop.
    >
    > Engine has 4400 hours, 100 hours since overhaul.
    >
    > A) POH says takeoff power and maximum continuous power is
    > full throttle at 2700 RPM.
    >
    > On take-off and climb with full throttle the tach only shows 2350-2400.
    > Straight and level full throttle tach only shows 2500.
    >
    > Temperature was 58 degrees F.
    > Estimated weight at takeoff (just me and 40 gal fuel) 2050lbs.
    >
    > Are these tach readings cause for concern?
    >
    > Thanks.
    >
    > Steve
    > N2009D




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    BAC-Mail mailing list
    BAC-Mail@beechaeroclub.org
    http://www.beechaeroclub.org/mailman/listinfo/bac-mail

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