Printing an 11 x 14 inch sheet on the Epson 9900 involves a ticklish problem: the paper jams against the roll cover. This crumples it top and probably bottom, where the crumpled paper can hit the print head. This could damage the print head. Collisions can happen both when the paper feeds for the first time, when it moves up and down as the sensors on the head measure and position it, or when you start printing, and it again adjusts up and down.
Fortunately, the solution is simple. You can hover over the printer, gently guiding the top edge of the paper with your hands, though that isn’t the best solution. Holding or taping another piece of paper onto the roll cover behind the sheet works better. You could also leave the cover in raised position, but then you wouldn’t have it to guide and support the sheet.