I can recall at least one dented projector at SELEM from this being done. Don't know how much you have invested in your projector, but why not purchase a pelican case locally and not take any chances? Either that, or just carry it on? I traveled with a similar sized projector to Chicago (a little larger, actually), as a carry on in a canvas tote and had no troubles from anyone. As long as it can fit under a seat, you should be ok.
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