A looong time ago, I believe the original Rockwell 500 (IIRC) was flown across the USA with the 2nd prop stowed in the cabin.....
n 1950, when the developers were working to satisfy Civil Aeronautics Authority (CAA) regulations for certification of the 500, they chose a novel method of demonstrating its single-engine safety and performance: They removed one of the two-bladed propellers, secured it in the aft cabin, and flew from Bethany to Washington, D.C. on one engine. There they met with CAA personnel, then replaced the propeller and returned to Oklahoma in the conventional manner.