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Touring Motor Gliders Association (TMGA)
  • Landing Gear Rigging and Check - Aermot Factory Communication


    Ethan Graham

    Summary:  Description of the maintenance procedures and rigging procedures for the retractable landing gear mechanisms for the Ximango touring motorglider.


     

    From: Castilho <lcastilho@aeromot.ind.br>
    Date: June 20, 2008 3:50:07 PM EDT
    To: bruce@schimmel.com, ximangoUSA@aol.com, Claudio Viana  
    <cviana@aeromot.com.br>, jjotz@aeromot.com.br
    Subject: Landing Gear Rigging and Check
    Reply-To: lcastilho@aeromot.ind.br

    Gentlemen,

    1. In a normal landing condition the landing gear assembly cannot collapse or retract if it is assembled and rigged correctly.

    2. There is not a specific AEROMOT Service Bulletin with instructions for Landing Gear down-lock rigging. Basic maintenance instructions are specified on the Maintenance Manuals (MM) and based on XOG Community Members comments they will be revised to emphasize an add functional tests to check correctly the landing gear down-lock. In the meantime, please see attached page 1.37 of AMT-200S Maintenance Manual with some notes and the comments below about points that we consider basic for the present discussion about Ximango landing gear:

    2.1 Two and a half (2.5) turns clockwise (CW) on stop screw (6), from  a position of control arm(3) and rod(5) considered as "aligned",  causes a little and desired inverted position between these mentioned parts. We agreed with XOG Community Members that Maintenance Manual does not present a clear specification how to get an "aligned" position of control arm (3) and rod (5) as the start point to the 2.5 turns.

    The manufacturing procedure considers the control arm (3) and rod (5) as aligned when the three articulated points A, B, C (see figure in Maintenance Manual) are in the same line. Two and half (2.5) turns CW is the basic reference to obtain the desired inverted position and it is done in the factory not needing to change anymore. We do not have also reports about loosening in service of lock nut that locks the stop screw (6). The lock nut is a counter nut and for its loosening it is necessary to unlock it mechanically.

    2.2 From AMT-100 S/N 100.035 and on, and in this case includes all  AMT-200, AMT-200 S and AMT-300 already manufactured, AEROMOT has incorporated an additional locking device installed in the connection of link rod (1) and Control arm (3) as shown on page 1.37 of AMT-200S MM. See additional details and parts on figure 3 IPC AMT-200S attached.  In that time (Oct 1993), two occurrences were reported in Brazil of unexpected retracting of landing gears, one during a hard landing and another during taxing on irregular runway.

    To eliminate this kind of occurrence, the additional locking device was introduced in the production series and a Service Bulletin (SB 100-32-017) was issued only for AMT-100 (S/N 100.001 to 100.034) application.

    2.3 To check if the additional locking device is working, put the motorglider on jacks, and press control arm (3) and rod (5) upward,  as indicated on Maintenance Manual figure attached. If the landing gear starts to retract, the hook (See item 37 IPC figure 3) is not locking.  Basically, the main cause for the incorrect position of this hook is an incorrect rigging of the stop screw (item 6 in the Maintenance Manual figure).  Please check, adjust stop screw (6) as specified on item 2.1 and check again the additional lock pushing the control arm(3) upward.

    3.  For information only, Maintenance Manual page 1.36 attached specifies the basic instructions for up-lock rigging. The up-lock rigging is independent of the down-lock rigging.

    4.  For information only, Maintenance Manual page 1.38 attached specifies the basic instructions for the control lever rigging.  Down-lock rigging is not affected by the control lever rigging. Landing gears are down-locked only by additional lock system and by the inverted position of control arm and rod.

    5. When a landing gear assy is replaced due to an accident (for example, an emergency landing where one or the two landing gears were seriously damaged or broken), new landing gears are installed as well as torque tubes, etc and a complete rigging of the system is necessary because this kind of repair is considered as a major repair. Basic instructions are provided by AEROMOT in these cases when consulted by the customer or the maintenance shop.

    We would like to know if Mr. Cooper's motorglider, which had the landing gear retracted during landing, suffered a landing gear major repair or a maintenance before the occurrence. Information of motorglider serial number and total flight time will be appreciated also.

    We don't know if comments above answer all XOG Community Members questions. Please don't hesitate in contact for further items.

    Regards
    Engº Luiz Antonio de Castilho
    AEROMOT - Engineering and Quality Division

    fig 1  fig2  fig3  fig4


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