[v0.6.0] Ground Check - Propeller test produces 300 RPM drop maximum



  • @Martyn

    I have installed v0.6.0 and on ground checking noticed when doing the propeller check that RPM drops 300 RPM at a maximum in this version. As per the official manual (and up to v0.5.2) the drop could be over 500 RPM as expected, and it was up to the pilot to avoid a drop over 500 RPM by increasing the propeller. I see nowhere in the official aircraft manual stating the maximum drop of 300 RPM

    Text from Piper official manual
    a561375c-e956-4f38-9005-eb62b390f68d-image.png

    Initiating test
    86fc216e-4c8d-4448-8410-aa5363d8dad4-image.png

    propeller full decreased (maximum 300 RPM drop)
    6fe954da-94ec-4668-a36f-1111586f5f63-image.png



  • The POH also does not specify the minimum drop expected during this governor check. The purpose of this check is to insure that oil is flowing to the prop governor and it is working... The only requirement is that the RPM drops, and the oil pressure also drops during this test. 1700 - 2700 RPM is the normal expected operating range of the prop governor.

    However, after viewing a video of this check being performed on a real Arrow III, I agree that the RPM drop should exceed the current 300 RPM...



  • I came back to the normally aspirated III after flying only the turbo for a while, and I confirm that indeed version 6 is incorrect regarding that.
    I have 50 hours on the real one, and I confirm that EVERY time you make the prop check, you have to bring the lever back forward in time or else you drop more than 500 RPM.
    @Martyn : could you correct this in the next update ? Thanks.



  • @JOM4021 Thank you for verifying this on a real aircraft.

    @Martyn FYI I have opened a ticket for this already.



  • @RetiredMan93231
    Just as a technical explanation: the reason why the RPM drops below 1700 on the ground check is that the aircraft is static and thus reducing RPM on ground creates more torque on the engine than it would be in the air.
    When doing my qualification on the aircraft (it was my first variable pitch aircraft), my instructor showed me a "trick" when practicing power off patterns: pulling the prop lever aft to increase the pitch and thus lengthen the glide distance. But he stressed that, if it was not in a real emergency, it could ONLY be done with the power at idle of course, and a windmilling prop.


  • JF Staff

    Thanks for the feedback. We're looking into this.



  • @Martyn I see a fix for the prop rpm drop issue is on the list for v0.7.0, that´s amazing! TY!

    23302019-64db-4793-b3a1-8ef282a85037-image.png

    Just for your information, the Turbo has the same issue but there´s no fix for it in the list of v0.2.0 though.

    e70f0cab-ace3-4562-9de6-49345c63280f-image.png