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  • Re: Can't remove gearbox drain plug

    by » 8 years ago


    Hi Mike,


    Wikipedia definition:

    Galling is a form of wear caused by adhesion between sliding surfaces. When a material galls, some of it is pulled with the contacting surface, especially if there is a large amount of force compressing the surfaces together. Galling is cause by a combination of friction and adhesion between the surfaces, followed by slipping and tearing of crystal structure beneath the surface. This will generally leave some material stuck or even friction welded to the adjacent surface, while the galled material may appear gouged with balled-up or torn lumps of material stuck to its surface.
    Galling is most commonly found in metal surfaces that are in sliding contact with each other. It is especially common where there is inadequate lubrication between the surfaces. However, certain metals will generally be more prone to galling, due to the atomic stucture of their crystals. For example, aluminum is a metal which will gall very easily, whereas annealed (softened) steel is slightly more resistant to galling. Steel that is fully hardened is very resistant to galling.
    Galling is a common problem in most applications where metals slide while in contact with other metals. This can happen regardless of whether the metals are the same or of different kinds. Metals such as brass are often chosen for bearings, bushings, and other sliding applications because of their resisitance to galling, as well as other forms of mechanical abrasion.




    I have never seen one that can't be removed. Try again. Heat the surrounding hole again until it's hot. Use a breaker bar and socket on the plug head. While someone is applying considerable pressure to unscrew the plug rap the end or edge of the breaker bar with a metal hammer "smartly" 1-8 times until it loosens. Don't be afraid to hit the plug just don't reel back with the hammer so hard and try to break it off. It will come out, just change the technique a little.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell


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