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Thread: Elevator deflection mismatch

  1. #1
    cozzmo81's Avatar
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    Default Elevator deflection mismatch

    While I had my plane level for rigging the wings after installation of the new wing struts I figured it would be a good idea to check the rest of the rigging on the aircraft. I have not yet flown the aircraft so I'm not sure about its flight characteristics. I was a bit skeptical when I noticed the left elevator had a bendable trim tab installed on it. During my initial checks of the elevator deflection I am getting the correct deflection on the RH elevator, but the LH deflection is about 2-3 degrees off from the right. Since the elevators are bolted together at the horn is there any way to compensate for this mismatch? I also found that the stabilizer trim was restricted from going all the way up due to the cutouts in the stabilizer trim plates on the fuselage being too small. At least that is a simple fix.

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    Default Re: Elevator deflection mismatch

    Quote Originally Posted by cozzmo81 View Post
    I also found that the stabilizer trim was restricted from going all the way up due to the cutouts in the stabilizer trim plates on the fuselage being too small. At least that is a simple fix.
    I looked at a Pacer once and during a prebuy inspection I noticed the trim yoke was installed upside down (V pointing down instead of up) and that while trimming down it was being blocked from full nose down low AOA high speed trim setting by the inspection cover at the front of the horizontal stabilizer.

    I do not know if the trim yoke being installed upside down was causing trim travel problems, I did not fly it, but I would bet that if the inspection cover was stopping high speed trim travel prior to the yoke hitting its stop that full nose up low speed trim would not be attainable due to the upside down yoke would be hitting its stop prior to reaching normal full high AOA trim setting.

    I would check your jackscrew yoke to make sure it's intalled V pointing up. I beleive the inspection covers were not the problem in the Pacer I looked at, but the upside down yoke was causing the trim crank to crank beyond its normal high speed trim max setting and the horizontal stabilizer to bump the inspection cover prior to the yoke hitting the stop.
    Last edited by PA-16; 05-06-2018 at 10:27 AM.

  3. #3
    cozzmo81's Avatar
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    Default Re: Elevator deflection mismatch

    Thanks for that tip. I will check it the next time I'm at the hangar.

  4. #4
    cozzmo81's Avatar
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    Default Re: Elevator deflection mismatch

    I checked the trim Yoke and it is installed correctly. with the stab inspection panels on the fuselage removed I can get the proper trim deflection. Now to figure out the difference in elevator angles.

  5. #5
    Administrator Steve Pierce's Avatar
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    Default Re: Elevator deflection mismatch

    Adam, I would loosen the bolts holding the elevators together and see if that gives you a little bit of play to better align them. I don't think it is a big deal. A lot of airplanes have a littledifference in elevator angles to add some differential pressure to the two to add some stability.

  6. #6
    cozzmo81's Avatar
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    Default Re: Elevator deflection mismatch

    Quote Originally Posted by Steve Pierce View Post
    Adam, I would loosen the bolts holding the elevators together and see if that gives you a little bit of play to better align them. I don't think it is a big deal. A lot of airplanes have a littledifference in elevator angles to add some differential pressure to the two to add some stability.
    Thanks Steve, I'll give that a try and see if I can get them a little closer.

  7. #7
    59pacer's Avatar
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    Default Re: Elevator deflection mismatch

    Is it possible to buy replacement elevator bellcranks? There doesn't appear to be anything available in the Univair catalog.

  8. #8
    Administrator Steve Pierce's Avatar
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    Default Re: Elevator deflection mismatch

    You might try Airframes Alaska. http://www.airframesalaska.com

  9. #9
    59pacer's Avatar
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    Default Re: Elevator deflection mismatch

    Thanks, Steve. I emailled them and got some useful information, but they don't sell the bellcranks individually. I'll have to handle the problem differently. Thanks.

  10. #10

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    Default Re: Elevator deflection mismatch

    You could also weld up the holes and re drill them in the correct location.


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