P was operating a bulldozer when the bulldozer rolled and P was thrown from the safety of the bulldozer's rollover protection system. The bulldozer landed on his legs, causing severe injury. P sued D and Indiana Mills & Manufacturing, Inc. (IMMI) alleging that the bulldozer incorporated an IMMI seatbelt that was defective in its manufacture, design, and warnings. Because the seatbelt was manufactured more than 10 years earlier, the district court dismissed the claims against IMMI under a statute of repose. The claims against D proceeded. The district court later confirmed that D could be held responsible under Iowa law for defects in the seatbelt because the seatbelt was a component part of the bulldozer. P asserted three separate theories of liability: (1) inadequate warnings; (2) design defect; and (3) manufacturing defect. The court granted D's motion for a directed verdict and dismissed P's manufacturing defect claim. The jury returned a verdict in favor of D on the remaining claims. P appealed. P argues in part that the district court erred when it granted D's motion for a directed verdict on his manufacturing defect claim.