Stationair8.
You're not thinking of the prototype Aero Commander are you?
In 1950, when the developers were working to satisfy 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. The flight received nationwide coverage in the press
