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Thread: Where should my RPM Max out?

  1. #1

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    Default Where should my RPM Max out?

    I have a PA-22-160. The prop is a Sensenich M74DM. Max RPM while parked is about 2250-2300. In Cruise 2500 doing about 110Kt. Are these normal values?

  2. #2
    bvmbandit's Avatar
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    Default Re: Where should my RPM Max out?

    Quote Originally Posted by wiegerket View Post
    I have a PA-22-160. The prop is a Sensenich M74DM. Max RPM while parked is about 2250-2300. In Cruise 2500 doing about 110Kt. Are these normal values?
    Cruise or climb prop? What pitch prop?

    - Vern

  3. #3

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    Default Re: Where should my RPM Max out?

    is there a cruise and climb variant of the M74DM?

    Sent from my EVR-L29 using ShortWingPipers.Org mobile app

  4. #4
    CamTom12's Avatar
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    Default Re: Where should my RPM Max out?

    There's different prop pitches. Mine is pitched at 60" and is squarely in the "cruise" category.

  5. #5
    Gilbert Pierce's Avatar
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    Default Re: Where should my RPM Max out?

    74DM6-58” is a climb prop. Extreme cruise props are 61”

  6. #6

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    Default Re: Where should my RPM Max out?

    Years ago I had a PA-22-160 that I used for banner towing. When I got the airplane it had a 60Ē pitch prop. Flew fine but didnít tow very well. Had it repitched to 53Ē, and it climbed like no tomorrow. Didnít cruise worth a damn though! All that said, the TCDS provides limits for static RPM. For the PA-22-160 with an M74DM, your limits are not over 2450, and not under 2250. Diameter limits are not over 74Ē and not under 72Ē since you indicate that static you are 2250 -2300, that would indicate either you have a cruise prop (60 or 61Ē pitch) or a sick engine. Based on the owners manual, 75% power sea level should be 125 and 75% at 7000í should be 134 mph. 75% at sea level is about 2475 RPM based on the O-320 owners manual. Iím guessing 75% at 7000í is going to be 2700 rpm (donít have the time to follow all those lines on the chart, and you didnít say what your MAP is) You are claiming 110 kts ~126.5 mph so it sounds like you are doing exactly what the book says you should be doing.


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  7. #7

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    Default Re: Where should my RPM Max out?

    On my Pa-22-150 with a 74DM6-58 my static RPM is 2400.

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