The ornamental design for a mountingstand for attaching an accessory to an engine, substantially as shown and described.
FIG. 1 is a front perspective view of the mounting stand for attaching an
accessory to an engine showing my design;
FIG. 2 is an end elevation view thereof;
FIG. 3 is a side elevation view thereof;
FIG. 4 is a bottom plan view thereof; and
FIG. 5 is a perspective view of a mounting stand for attaching an accessory
to an engine showing a second embodiment of my new design, it being
understood that the difference resides in the concave upper support
surface being smooth.